Volume 69 (2024)
WOOD RESEARCH Volume 69, Number 1
In Korea, in accordance with regulations MOLIT notice 2023-24 regarding the flame retardant performance of building finishing materials and fire spread prevention structure, it is mandated that flame-retardant materials have a total heat emission less than 8 MJ/m2. Consequently, our study aimed to determine the quantity of flame-retardant treatment required to meet MOLIT notice 2023-24 for Korean larch and Japanese cedar, as commonly used exterior materials in construction. To this end, we investigated using a cone calorimeter to observe changes in the THR (total heat released) depending on the SCFI (solid content of flame-retardant impregnation). Our simple linear regression analysis indicated that the SCFI needed to satisfy the prescribed flame-retardant standard of 8 MJ/m2 was 93.9 kg/m3 for Korean larch and 144.6 kg/m3 for Japanese cedar. As a result, we established optimal impregnation levels of flame retardant for both species
This article is focused on the research of particleboards (PB) composed of wood particles from spruce logs and recycled crushed plastic granulates. Crushed plastic granulates sized from 1.0 to 4.0 mm were obtained from worn automobiles by recycling, specifically painted and unpainted bumpers. The proportion of plastic granulate in the particleboards represented 10%, 15%, and 20% of the total weight of the composites. In the production of PB, urea-formaldehyde resin and paraffin emulsion were used as a binder and ammonium nitrate was used as a hardener. The aim of the article was to compare the selected properties of PB containing plastic filler with pure PB. Mechanical properties (tensile and bending strength), and physical properties (water absorption and thickness swelling) were evaluated according to EN 319, EN 310 and EN 317. Based on the results, it can be stated that the bending strength and physical properties of PB containing plastic filler were significantly better compared to pure PB. On the contrary, the tensile strength values were lower in most cases
Caragana korshinskii Kom. powder was used as the experimental material and wheat bran as the binder to produce high-quality biomass molding fuel (BMF) pellets. A series of experiments involving pellet production were conducted in different molding temperatures and at different moisture contents with different percentage of wheat bran by a newly-developed pelletizer using a die heating production method. The biomass molding process was optimized by single factor and orthogonal test with the fuel relaxation density, mechanical durability and molding pressure as indexes. The experimental results showed that the optimum moisture content was 20% by mass percentage of wheat bran is 9% by mass and molding temperature is 140°C in order to get the best quality of high-strength BMF pellets with relative low molding pressure
In order to promote the universal application of bamboo materials as well as to provide reference for the study of the performance of bamboo, four kinds of flame retardants (boric acid (BA), borax (BX), ammonium polyphosphate (APP), disodium octaborate tetrahydrate (DOT)), two kinds of ultraviolet light absorbers (UV-531, nano TiO2) were added into waterborne polyurethane (WPU) to synthesize 5 kinds of modified coatings and coated on the surface of bamboo to make test materials. The flame-retardant analysis of the coated samples comprehensively explored the changes in flame retardancy of the test material after treatment. And the anti-aging test was carried out to investigate the color difference and adhesion change of the coating sample. The results show that the optimum flame retardant and anti-aging coating composition was obtained as 20% solid content of WPU, 8g coating amount of modifier, with the mass ratio of BA/BX/APP /DOT/water being 75:75:7:42:600, and the amount of UV-531 added being 1%
This study explores the mechanical properties of hybrid eucalyptus wood, with a focus on dynamic and static moduli of elasticity (MOE), which is crucial for understanding the stiffness behaviour of wood. The research employs acoustic and static measurements on samples prepared from six trees sourced from Winneba and Amantia in Ghana. The results reveal significant variations in static and dynamic MOE, with higher static MOE observed in both Amantia and Winneba samples. However, Winneba and Amantia samples at the tree level were found to be insignificant statistically. The densities of the samples from the two locations, Winneba and Amantia, were found to be significantly different. Correlation studies revealed strong relationships between wood density and static MOE, as well as static and dynamic MOE, providing valuable insights into the comprehensive characterization of the eucalyptus globulus species grown in Ghana
The article is devoted to determining the basic physical and mechanical properties of sheet materials up to 1.5 mm thick based on wood shavings and PVAc glue with a high proportion of water, pressed under high pressure up to 25 MPa and a temperature of around 190°C, so that the softening of lignin caused by the generated steam, allow to create a compact and non-crumbling surface. In order to characterize the physical-mechanical properties of the new wood-based sheet material with minimum thickness and characteristic elasticity, tests according to the CEPI (Confederation of European Paper Industries) standards were adopted. Procedures for tensile strength according to ISO 1924-2 (2008), Burst strength according to ISO 2758 (2014), puncture according to ASTM D781-68 (1973), water absorption according to ISO 5637 (1989) and porosity according to TAPPI Test method T460 were applied
The aim of this study was to analyze the extractive composition of the wood and bark of cajuput (M. cajuputi subsp. cajuputi) to consider the end use material according to the characteristics of the its extractives. Results showed that the extractives properties of M. cajuputi, i.e. the contents of n-hexane, methanol, hot water extractives and total phenolic content (TPC), flavonoid content (TFC) and total polysaccharides (TSP) were 0.84 to 1.05%, 1.00 to 1.03% and 1.43 to 1.46%, and 19.2 to 38.7 and 23.2 to 27.3 mg GAE/g dried extract, 11.8 to 16.0 and 7.55 to 14.0 mg QE/g dried extract and 79.3 to 102.8 and 148.8 to 165.9 mg Glu/g dried extract, respectively. Bark had higher extractive levels than wood. In addition, TPC and TSP in the bark were greater than in the wood parts, whereas the reverse trend was found in TFC. The relatively high contents of TPC and TFC in the wood and bark suggest that their potential antioxidant properties. Based on the GC-MS analysis, the high content of sterols-steroids (31.4%) and triterpenoids (21.9%) in the bark part will have potential in the field of pharmacology
The Amazon rainforest displays wide ecological diversity, reflected in its wood variation. The study evaluated the influence of different locations on the properties of wood from native tropical species extracted from the Brazilian Amazon. The most frequent species in the locations were selected, and a total of 104 trees were extracted. The logs were sawed breakdown to make beams (50 × 110 × 2,000 mm). The wood density and mechanical resistance of these samples were determined. The wood density ranged of 0.25-1.00 g/cm3, modulus of elasticity and rupture in static bending ranged of 5,982-19,025 MPa and 35-204 MPa, respectively. For compressive strength parallel to the grain, the range was 24-111 MPa; the strength of wood compressed parallel was 20-245 MPa, and the shear strength was 50-245 MPa. The study detected differences in the physical and mechanical properties of the woods regarding the origin of the sites (Amazonas-Pará/Brazil), with the modulus of elasticity and the wood density showing the greatest variations
In our study we estimated under two different scenarios the historic and future carbon balance of the Hungarian harvested wood product (HWP) pool using the HWP-RIAL model. We also estimated the effect of product and energy substitution and the magnitude of avoided emissions based on international substitution factors. According to our results in the period 1985–2021 the average of the HWP net emissions plus substitution effects was -3,800 kt CO2. In this period the 49% of the forest industry-related climate benefits was attributable to carbon storage in forests, while 4% was attributable to carbon storage in wood products and 47% to product and energy substitution. According to our projection the HWP net emissions plus substitution effects could reach -14,994 kt CO2 up to 2050 under an intensified domestic wood processing industry. This means that product substitution benefits could be tripled, while the net removals of the HWP pool could be 5 times higher than the historic values
Application of agents to increase the dry strength is one of the ways of improving the physical-mechanical properties of papers. In the presented article, we are dealing with the application of modified starches to the pulp mass in order to increase the strength parameters of hygienic papers. In laboratory experiments, 8 types of agents were tested, which differed in charge level, molecular weight and cross-linker level. Strength parameters, porosity and water absorption were evaluated during the laboratory tests. The most important strength parameter in the production of tissue papers is the tensile strength, the most suitable parameters for the production of tissue papers were achieved when applying the product ECO 2777. By monitoring the influence of the dose of starch, it was found that the optimal dose is 3 kg per ton of absolutely dry pulp, when there is an increase in the tensile strength by 18%, the burst strength by 41% and while maintaining the required values of stiffness, porosity and water absorption
In this study, computer aided technology was utilized to improve the traditional grid shoulder mortise-and-tenon joint (GSMTJ). Firstly, the traditional GSMTJ was redesigned through using separated loose tenon by the computer aided design (CAD) software called AutoCAD. And then the mechanical strengths of the traditional GSMTJs and the improved GSMTJs were compared and analyzed using the experimentally validated finite element method (FEM) based on the computer aided engineering (CAE) software called ABAQUS. Finally, the GSMTJs were further investigated from perspective of manufacturing efficiency using the computer aided manufacturing (CAM) software called JDSoft SurfMill. Based on the above simulation analysis, the improved GSMTJ was validated to be equivalent strength, high manufacturing efficiency increasing by 11.5%, low processing load ratio decreasing by 30%, as well as less wood material cost reducing by 3.6% compared with the traditional GSMTJ. The proposed improved GSMTJ was validated to be more suitable to modern wood processing machines. In addition, the methodology of combining the CAD, CAE, and CAM to wood products design was proofed efficient, economic, and feasible, and can be also used in design of other products
In the paper was analysed the influence of three different container types, used for cultivation of Pinus nigra and Pinus sylvestris seedlings, on dimensions of their anatomical (resin ducts width, resin ducts number, tracheid number, tracheid width, wood rays height) and morphological (height, root collar diameter, sturdiness coefficient) elements, and on proportion of wood, bark and pith, as well. Two-factorial ANOVA showed that container type affects a lot all investigated anatomical traits by both species, but on the other side, these species varied between each other just in terms of tracheid width and wood rays height. Based on descriptive statistics, significantly lower values of all studied anatomical elements were recorded by biodegradable compared to plastic containers. As for P. nigra seedlings, they showed the best anatomical performance in Plantagrah I, while Hiko V-120 SS was the most suitable for P. sylvestris. The highest proportion of pith and bark was recorded in biodegradable container. As for morphological parameters, such as height and root collar diameter, higher values were recorded by plastic containers
The physical and mechanical properties of 40-year-old coconut stem were investigated in different radial directions and height positions. The results showed that in the radial direction, the properties of the number of vascular bundles (NVB), density, shrinkage, compressive strength parallel to the grain (CS), modulus of rupture (MOR), and modulus of elasticity (MOE) decreased continuously from the outer area to the inner area, except for the water absorption (WA) value which increased from the outer area to the inner area. The density and MOE decreased from the bottom to the top in the height direction while NVB and WA increased. The shrinkage, CS, and MOE first increased and then decreased from the bottom to the top. NVB in coconut stem affects the density and determines the main mechanical properties of CS, MOR, and MOE. The analysis of variance (two-way ANOVA) showed a significant difference in density, NVB, WA, CS, MOR, and MOE in radial direction and height position. These findings can be useful for the development of new applications for coconut stems, such as in construction, landscaping, or furniture manufacturing, as well as for improving our understanding of their structural characteristics
In order to strengthen the anti-mildew and anti-aging properties of bamboo when exposed outdoors, the glued laminated bamboo was impregnated with four different kinds of anti-mildew agents: tebuconazole, 3-Iodo-2-propargyl butyl carbamate (IPBC), NaBF4/didecyl dimethyl ammonium chloride (DDAC), boric acid/borax, and waterborne polyurethane coatings modified with boric acid/borax and triazole (UV1130), nano-TiO2 and nano-SiO2 were coated respectively. The modified coated glued laminated bamboo was characterized and analyzed through the experiments of wear resistance, three-point bending resistance and mildew resistance. The results showed that the glued laminated bamboo impregnated with 0.5% NaBF4/DDAC, and then coated with the waterborne polyurethane modified with boric acid/borax and nano TiO2 (the mass ratio:7.5/7.5/1.0) possessed the best mildew resistance, mechanical properties and weather resistance
This research aimed to determine the thermal characteristics of sengon wood due to drying at temperature of 70, 80, and 90oC with air velocity of 1 and 3 m/s using infrared (IR) and combined infrared-hot air (IR-HA) method. The thermal characteristics analyzed included temperature distribution, reduction in moisture content, and drying rate. The results of drying wood samples using IR method showed that the fastest drying time was obtained at 90oC with air velocity of 1 m/s. However, for combined IR-HA method, the optimal condition was achieved at air velocity of 3 m/s. The largest drying rate attained using combined IR-HA method was 0.27 g/min, while the smallest was recorded at 0.094 g/min with IR method. These results showed that combined IR-HA method produced a more evenly distributed temperature and faster drying time compared to the IR method
WOOD RESEARCH Volume 69, Number 2
The stability of the surface of UV-irradiated wood samples was investigated after 12 years of storage in total darkness at room temperature. The investigated specimens were earlywood and latewood of Scots pine sapwood, earlywood and latewood of spruce, earlywood of ash, beech and hybrid poplar. The thin (1 mm tick) samples contained only earlywood or latewood, and the tangential surfaces were used for infrared spectrum measurement. For comparison, the non-irradiated natural surface (back side) of the specimens was used for infrared spectrum measurement. Natural wood surfaces were stable during the storage. Only ether linkages in hemicelluloses showed minor degradation at 1175 cm-1 wavenumber. Lignin molecules remained stable during the 12-year storage period on both UV irradiated and non-irradiated side of the specimens. In contrast, UV irradiated samples suffered alterations during the 12 years of thermal treatment at low temperature (20-25°C). Hemicelluloses in photodegraded surface layers underwent thermal degradation and oxidation processes, generating new carbonyl groups. Extractives also presented absorption increase in the conjugated carbonyl region
This paper targets the validity of a novel numerical model for analyzing CLT under out of plane loading. This numerical model was initially developed for determining the shear lag effect that appears in laminated thin walled composite beams. A parametric study was conducted in order to determine the influence of orientation of layers in CLT panels on bending strength and deflection. For confirming the accuracy of the proposed model, the results from the numerical model are compared with the external results of the computer software Ansys. The differences in bending stress vary from 0.27% to 1.69% depending on the orientation of layers and for deflection the differences are ranged from 2.25% to 7.42%. A numerical study was conducted and obtained data corresponds to results obtained from experimental study. It was concluded that the proposed numerical method can enough precisely predict the behavior of CLT under out of plane loading
Basic physical and mechanical properties of lignocellulosic liners up to 1.5 mm thick with a compact and non-crumbling surface based on wood wool and thermoplastic water based glues were determined. PVAc and starch glue with a high proportion of water content were used. The dry mat was pressed gradually under high pressure up to 28 MPa and a temperature of around 190°C with the release of steam. Tests according to the CEPI (Confederation of European Paper Industries) standards were adopted. Procedures for tensile strength according to ISO 1924-2 (2008), Burst strength according to ISO 2758 (2014), puncture according to ASTM D781-68 (1973), water absorption according to ISO 5637 (1989) and porosity according to TAPPI Test method T460 were applied
The spruce (Picea orientalis), maple (Acer pseudoplatanus), sapele (Entandrophragma cylindricum), cypress (Cupressus sempervirens) and mulberry (Morus alba) woods, which are among the wood types commonly used in making musical instruments, were subjected to chemical modification by propionic anhydride for 1 h, 3 h and 6 h reaction times. The changes in dimensional stability, sound velocities, modal frequencies and dynamic elasticity modulus values of wood samples after modification were investigated. According to the results obtained, as the weight gain values occurring depending on the reaction time increased, the dimensional stability increased in all wood types. When the acoustic properties were examined, it was determined that individual changes occurred at different values depending on the wood type and chemical modification times
In this study, the influence of three different drying methods on the liquid permeability of sapwood and heartwood of Eucalyptus urophylla was investigated. The liquid permeability of the dried wood was assessed by measuring the maximum amount of dyeing solution uptake using the capillary rise method. Subsequently, the microscopic structure of the dried wood was examined by scanning electron microscopy (SEM). The results indicated that the liquid permeability of sapwood dried by microwave vacuum drying (MVD) and conventional kiln drying (KD) was significantly more effective than that of air drying (AD) treated wood. However, there is no significant difference in the effect of MVD and KD on the liquid permeability of sapwood. The liquid permeability of heartwood treated with MVD is significantly better than that treated with KD and AD, and the effect in the effects of AD and KD on the heartwood is not significant. The increased permeability of Eucalyptus urophylla wood can be attributed to the occurrence of macro-cracking or micro-structural damage in the test specimens, resulting from the dislodgement of perforated plates within the wood cells, the rupture of the intercellular layer between vessel and axial parenchyma cells, as well as the rupture of the pit membrane…
The objective of this study was to evaluate the modulus of elasticity and wood quality for structural use in standing trees of Pinus montezumae Lamb. in a natural forest. An acoustic method was used, measuring the ultrasonic flight time for one cross-sectional and two longitudinal sections in 70 trees. Significant differences were found between the two longitudinal moduli of elasticity, and the P. montezumae trees in the study area show potential for structural use according to the modulus of elasticity. It is concluded that for sustainable management, wood of medium quality would be obtained in the same proportion for the first two sections of the tree stems, while high-quality logs would be obtained in the second longitudinal section (2–4 m)
EVALUATION OF WOOD DAMAGE AND FRACTURE BEHAVIOR BASED ON ENERGY ENTROPY OF ACOUSTIC EMISSION SIGNALS
In order to assess the damage and fracture behavior of wood under continuous loading, an energy entropy and b-value associated with the acoustic emission (AE) signal were defined to quantitatively describe the release of strain energy during loading. Firstly, the acoustic emission signals of the wood in the three-point bending test were collected. This paper presents the concept of energy entropy according to the definition of information entropy. In order to further evaluate the strain energy intensity released by the damage behavior of the wood specimen, the acoustic emission b-value was defined. Finally, by jointly analysing the dynamics of these two parameters, the test process can be divided into three phases. The results show that even in the elastic phase, micro-destructive behavior occur inside the wood specimen; in the plastic phase, the wood specimen is not only subjected to macroscopic damage, but also often accompanied by fine cracks inside
This study focuses on the effects of chemical treatment using polyethylene glycol (PEG) and physical treatment via steam explosion and microwave, with a comprehensive analysis using ATR-FTIR, X-ray diffraction, Keyence VR 6000 optical profilometer, and SEM. The aim is to elucidate alterations in bamboo cell walls following these treatments compared to untreated bamboo. The results reveal significant modifications in the chemical composition and crystalline structure of bamboo cell walls post-treatment. ATR-FTIR analysis indicates changes in functional groups, suggesting chemical interactions and modifications in the molecular arrangement of cell wall components. XRD analysis further corroborates these findings by revealing shifts in crystallinity and peak intensities, signifying structural rearrangements, as evidenced by optical images and SEM micrographs
Extractives and ash contents, share of latewood and annual rings width were analyzed in wood at different heights and different zones of the Pinus sylvestris L. stem cross-section. Additionally, the high performance liquid chromatography (HPLC) with a conductometric detector was applied to determine the sulphate (SO42-) and hydrogen phosphate (HPO42-) anions concentrations in wood and bark of Pinus sylvestris L. stem. In this paper, based on the results it was observed, that generally extractives content increased in the direction from sapwood perimeter to middle heartwood and pith adjacent heartwood zone. Moreover, the results showed that the greater share of latewood in annual rings the lower ash and extractives contents in the wood, but the higher sulphate (SO42-) and hydrogen phosphate (HPO42-) anions concentration. The sulphate (SO42-) and hydrogen phosphate (HPO42-) anions concentrations in the bark of the Pinus sylvestris L. stem were higher at the top than at the butt-end part
The suitability of three plant taxa namely: Bridelia ferruginea, Hura crepitans and Ricinodendron heudelotii as potential revegetation plants in desertified areas were assessed using Calquist’s wood anatomy indices (vulnerability and mesomorphy) using an ecological survey design. Temporal and permanent slides of transverse sections were prepared and vessel length and diameter (µm) measured using a Motic B3 Compound Microscope and vessel density determined for each of the plant taxa. The observed high vulnerability and high mesomorphy index values in Hura crepitans and Ricinodendron heudelotii indicates that they did not fall within the required ranges of 0 – 2.5 and 0 – 99 for the two indices respectively and cannot adapt well in xeric areas. However, Bridelia ferruginea fell within the range. In conclusion, Hura crepitans and Ricinodendron heudelotii are mesophytes while Bridelia ferruginea was xerophytic and can flourish in xeric areas, therefore, it possesses a great revegetation potential
This work aimed at utilizing wood anatomical traits to assess the compatibility or suitability of 9 species in the families where they belong since the earlier classification depended only on morphological characters and also to possibly deduce the permeability of their vessel lumen during wood treatment with preservatives of equal or different viscosity. Comparative stem anatomy of tree taxa Antiaris toxicaria Lesch. (Moraceae), Ficus exasperate Vahl. (Moraceae), Milicia excelsa Welw. (Moraceae), Dacryodes klaineana Lam. (Burseraceae) Canarium schweinfurthii Engl. (Burseraceae), Dacryodes edulis Lam. (Burseraceae), Erythrophleum suaveolens Taub. (Fabaceae), Pelthophorum pterocarpum De Cand. (Fabaceae), Pterocarpus soyauxii Taub. (Fabaceae) was studied. Observations on the transverse, radial-longitudinal and tangential-longitudinal sections showed that there were vast variations and few similarities in the vessel, axial parenchyma, ray cell and storied fibre distributions within and across families. Variations across the three ecological zones were found. The highest vessel diameter occurred in C. schwenfortii with 222.84µm (Burseraceae) followed by F. Exasperate with 196.42 µm (Moraceae) and P. pterocarpum with 187.23 µm (Fabaceae) across the three ecological zones. Vessel diameters were in direct proportion with the amount of rainfall while vessel frequencies were in negative proportion with the amount of rainfall across the ecological zones. Qualitative properties were not…
The aim of this paper is to create the model for prediction of carbon monoxide release rate (CORR) and smoke production rate (SPR) from heat release rate (HRR) of fast-growing wood species. The model is independent on wood species, thus is suitable for all fast-growing wood species. Three wood species hybrid poplar J-105 (Populus nigra × P. maximowiczii A. Henry), white willow (Salix alba L.) and black locust (Robinia pseudoacacia L.) were used for universal model creation. The heat release rate, smoke production rate and carbon monoxide release rate have been measured at three heat fluxes (25, 35 and 50 kW.m-2) by the cone calorimeter. The average values of CORR and SPR for all investigated wood species were 0.051 g.m-2.s-1 and 0.086 m2.m-2.s-1, respectively. Both dependencies of SPR and CORR on HRR have shown similar trends during the ignition phase (unstable trend) and during the intense burning phase (roughly linear increasing with HRR). The main difference was shown during the steady state phase (dependency of SPR on HRR is stable while dependency of CO on HRR is highly unstable). The results also proved a significant impact of wood density on these dependencies, thus, the neural network for prediction of SPR,…
Boric acid, antimony oxide minerals and huntite hydromagnesite minerals were used as auxiliary minerals in wood composites to change their flammability features. Composite samples were prepared by using different ratios of sawdust, huntite, hydromagnesite, antimony and boric acid combinations. The obtained samples were characterized by scanning electron microscopy (SEM) analysis to determine the structural and morphological properties of the composites. Thermal behavior of the composites was determined by differential thermal analysis-thermogravimetry (DTA-TG). Tensile and three-point bending tests were performed to understand the mechanical properties. Finally, the flame retardant performance of the samples was observed according to UL94 vertical flammability tests. It was concluded that wood composites containing inorganic minerals gained resistance against fire, a good synergistic effect was obtained in different additive types
The study examined the effect of stand composition and soil quality on radial growth of Quercus cerris (L.) grown in Vas County in Hungary. Twelve trees were randomly harvested, and the sampled wood pieces were extracted from the breast-height portion. Wood strips were machine-sanded, scanned for analysis in ImageJ. Climate data were obtained from a database of the Hungarian National Metrological Service. Mean annual-ring width was larger for trees harvested from mixed species planting site. Overall, annual-ring sizes for trees harvested from pure species stand that thrive on poor soils exhibited wider variation (62%). The same plot of trees had a latewood width variation of 82%. Precipitation correlated positively with annual-ring size with weak to moderate coefficient (0.13 – 0.32), whereas maximum temperature negatively correlated with annual-ring size on moderate coefficient (-0.42)
This paper describes the differences between the efficiency of enzymatic hydrolysis of selected lignocellulosic materials after pretreatment by cyclic freezing and thawing. It also discusses the analysis of the positive effect of alkaline conditions on pretreatment. The selected materials were Populus alba L., wheat straw from Triticum aestivum L. and Cannabis sativa. Three pretreatment methods were used to compare the efficiency of enzymatic decomposition of cellulose and cellulose accessibility. The best results show the wheat straw pre-treated at -20°C in the freezer with NaOH addition with a concentration of monosaccharides of 56.6 g.l-1 compared to initial hydrolysed material with a concentration of monosaccharides of 24.4 g.l-1. The results show better digestibility of grass compared to wood dendromass
WOOD RESEARCH Volume 69, Number 3
We evaluated the effects of phenol formaldehyde (PF) resin modification on Masson pine (Pinus massoniana Lamb.) wood cell wall in wet states. The penetration degree of PF resin into wood cell was determined using confocal laser scanning microscopy (CLSM). The micromechanical properties of PF-modified wood cell walls in wet state were analyzed by quasi-static nanoindentation and dynamic modulus mapping techniques. Results showed that the PF resin significantly affected the static viscoelasticity and nanodynamic viscoelasticity of wood cell walls in oven-dried and wet states. The cell-wall mechanics increased at a PF resin concentration due to the increased bulking effects, such as decreased crystallinity of cellulose. Furthermore, the microfibrillar angle (MFA) of cell walls was lower than that of the control wood cell wall. The cell-wall mechanics of PF resin-modified sample decreased small than control sample in wet states
The study investigated the effect of the amount of selected retardant coatings produced and used in the Slovak Republic on the fire resistance of spruce wood samples. Experiments were conducted for two different types of flame retardants: intumescent flame retardant (IFR) and inorganic salt-based flame retardant (IS). Based on different amounts of coating applied to spruce wood samples, the important parameters as mass loss, mass loss rate and fire spread rate were determined. The experiment consisted of applying a flame source to the samples at an angle of 45° and monitoring the mass of the samples during the experiment. The findings show that when IFR is used, the protection effect of the wooden samples increases linearly with the amount of coating. However, for the samples on which an IS flame retardant was applied, a higher amount of coating had no effect on increasing the fire resistance of the wood. In this case, the average total mass loss was the same regardless of the amount of coating, yet a significant retardation effect was observed compared to the untreated samples. Samples treated with IFR showed a lower total mass loss and also a significantly lower maximum mass loss rate compared to the…
THE INVESTIGATION OF NATURAL AGING BEHAVIOR OF SOME WOOD SPECIES MODIFIED WITH NATURAL PRESERVATIVES
This study evaluates the effects of 12-month outdoor weathering on Scots pine (Pinus sylvestris L.) and sessile oak (Quercus petraea L.) woods modified with tannins. Wood specimens were divided into four groups: Group A (control, natural aging (NA)), Group B (NA + 100% walnut tannin (WT)), Group C1 (NA + 50% WT and 50% pine tannin), and Group C2 (NA + 50% WT and 50% oak tannin). Group A showed density decreases of 4.3% for Scots pine and 4.7% for sessile oak, while Group B samples exhibited density increases of 2.6% and 1.6%, respectively. Group A specimens had hardness losses of 36.3% for Scots pine and 28.7% for Sessile oak, compared to reduced losses of 8.8% and 11.2% in Group B. Bending strength and modulus of elasticity also decreased significantly in Group A but were minimally affected in Group B. These results indicate that tannin treatments, particularly walnut tannin, improve wood durability and mechanical performance, offering an eco-friendly alternative to conventional treatments
In this study, bamboo fiber (BF) and polypropylene carbonate (PPC) were used to prepare BF/PPC composite materials. The single factor test combined with orthogonal experiment was used to investigate the effects of different hot pressing process conditions (hot pressing temperature, hot pressing pressure and hot pressing time) on the mechanical properties of BF/PPC composites. Based on the hot pressing process results, the filler nano-calcium carbonate (Nano-CaCO3), γ-aminopropyl triethoxysilane (KH550) and maleic anhydride (MAH) were added respectively to the composites to improve the interface between BF and PPC in order to increase the mechanical properties of the composites. The results showed that the reasonable preparation conditions of BF/PPC composites with the best mechanical properties were set at 170°C, under 1.9 MPa for 10 min. Compared with PPC samples, the tensile modulus, bending modulus and impact strength of BF/PPC composites could be increased to 102%, 38.69% and 65.13%, respectively. The optimal interface modification treatments have been proved that nano-CaCO3 with 10% content could increase the tensile modulus and impact strength to 70.53% and 65.84%, while the best result for the bending modulus of BF/PPC composites was modified with MAH with 2.5% content, which could increase to 28.46%
This paper presents an experimental study on the axial compressive static performance of the cylindrical timber-wrapped basalt fiber reinforced polymer (BFRP). Beech and black pine woods were used as cylindrical timber material, polyurethane (PUR) adhesive was used as the adhesive agent, and BFRP was used as fiber-reinforced polymers (FRP). The stress on compression tests was applied to 70 pieces of test samples prepared. The results showed that there was found out that the highest average stress value of 51.8 MPa was achieved inthe black pine cylindrical timber- BFRP wrapping- hollow core (Ø=70 mm)- the beech cylindrical timber blocks- BFRP wrapping samples under compression loading. The lowest average value stress value of 30.78 MPa was found in the black pine cylindrical timber- none hollow core samples. On average, the stress of the black pine cylindrical timber- BFRP wrapping- hollow core (Ø=70 mm)- the beech cylindrical timber blocks- BFRP wrapping samples were68% higher than the stress of the black pine cylindrical timber- none hollow core samples. The influence of the hollow core diameter and the BFRP wrapping type were found statistically significant
The article focuses on the experimental verification of wooden laths with a cross-section of 10 mm x 40 mm which were selected for active bending. The laths are made of pine wood and are 2 m in length. The research includes experimental measurements to determine the limit deformations achieved by bending the wood without chemical treatment, by applying compressive force to an originally straight beam, causing it to buckle and further deform. Ten bending tests of beams were performed, and from the same pieces, 21 tests were conducted using the four-point bending test to determine the flexural strength, and 30 tests to determine the global modulus of elasticity
The purpose of this research is to investigate the flexural properties and cyclic response of strengthened with fiber reinforced polymer (FRP) of glulam beam made from thermally modified rubberwood. The efficiency of three different FRP was assessed based on the bonding properties. The experimental results demonstrated that the glass fiber-reinforced polymer (GFRP) showed the strongest adhesion. Static and cyclic flexural tests were also carried out to study the behavior of glulam beams. The static test results indicated that double sides strengthened glulam beam enhanced their flexural strength. The strengthened glulam beams under static load demonstrated a reduced deformation rate due to increased modulus of rupture compared to non-strengthening glulam beam. The cyclic load test showed the strengthening effect on improving energy dissipation and ductility, while the impairment of strength did not affect
Porous activated carbon (PAC) from bamboo, sisal, and coconut coir fibres with two carbonization steps were prepared and the microwave absorbing characteristics in the frequency range of 8 GHz to 12 GHz were investigated. The PAC based on bamboo, sisal and coconut coir had BET surface areas of 354.79, 141.91, and 25.70 m2/g, respectively. The return loss of -27.3, -25.6 and -16.4 dB was achieved for PAC from bamboo, sisal, and coconut fiber at 10.46, 11.08 and 11.00 GHz, respectively. The microwave absorption of more than 99% for porous activated carbon of bamboo and sisal, and more than 90% for porous activated carbon of coconut coir fiber, is indicated by these return loss values. It is shown by these results that biomass resources can be considered a promising lightweight, cost-effective, and eco-friendly microwave absorber material
FRACTURE MECHANISM ANALYSIS OF HIGH-DENSITY FIBREBOARD BASED ON DIGITAL IMAGE CORRELATION TECHNOLOGY
This paper analyses the scattering images of the bending deformation of high-density fibreboards based on the digital image correlation (DIC) technique, so as to study its mechanical deformation law. Three-point bending tests were carried out on fibreboards using a mechanical testing machine with a non-contact measuring system. The measured values of the displacements of the grid nodes in the region of interest (ROI) were combined with the Moving least squares (MLS) method to construct the strains of the high-density fibreboards at different loading forces, thus deriving the strain values of the fibreboards during the bending deformation process. To further analyze its force deformation mechanism, this paper used a portable electron microscope and scanning electron microscope to analyze the damage situation at the fracture damage, and at the same time, it verified that the constructed strain field model was accurate
This study aimed to investigate the characteristic values of the human-seat interface in a normal sitting posture, and to numerically mode the load on the chair seat for the structural design of chairs. The stress distributions and the characteristic values of seat were measured under normal sitting posture by using a human body pressure distribution measurement system considering the effects of gender and body mass index (BMI). The stress distribution on the seat was then numerically modeled using three modeling methods. The observed results and the numerical analysisresults were compared. The results showed that an inverted U-shaped pressure distribution was observed in normal sitting posture. The stress was concentrated on the ischial tuberosity with a maximum value of 0.066 MPa. The ratio of the load on the seat to the gravity of the human body weight was about 65.3%. The numerical model established using the body pressure mapping method was superior to those of the uniform load method and the standard loading pad method in terms of stress distribution, maximum stress, and contact area
This article aims to investigate the characteristics of wood plastic composites (WPC) prepared from polyethylene (PE) reinforced with lignocellulosic fibers derived from the xylem and bark of Masson pine, fir, cypress, as well as from Moso bamboo. The surface polarity and elemental composition of fibers were determined through contact angle measurements and X-ray photoelectron spectroscopy (XPS). The lignocellulosic fiber/PE composites were manufactured through hot-pressing technique, and their water absorption, mechanical properties, and mildew resistance were evaluated. The results revealed that the surface free energy of xylem fibers was higher than that of bark fibers among the three conifer species. XPS analysis showed that the O/C ratio of bark was consistently lower than that of xylem fiber. Among the three conifers, the Masson pine bark had the lowest O/C ratio (22.25%), while its xylem fibers had the highest ratio of 41.64%. WPC made with bark fibers had better water resistance. Additionally, the composites reinforced with xylem fibers showed superior static bending strength, impact strength, and mildew-resistant properties as compared to the composites reinforced with bark fibers. WPC made from bamboo fibers exhibited the best water resistance, with a water absorption rate and thickness swelling rate of 1.83% and 1.42%, respectively. They…
In this study, strength properties of wood material reinforced with carbon fiber fabric, steel wire mesh and bamboo veneer were determined. Polyvinylacetate (PVAc) and polyurethane (PUR) glues (D4)were used for the lamellas obtained from Scotch pine (Pinus sylvestris L.) and eastern beech (Fagus orientalis L.). Compressive strength according to TS EN 408+A1; dynamic bending (shock) strength according toTS ISO 13061-10 and shear strength according to ASTM D 3110 were determined on 3 and 5-layers samples. According to the results, the highest compressive strength (62.8 N/mm2) was found in 5-layerseastern beech samples reinforced with carbon fiber fabric and bonded with PUR glue. The highest dynamic bending strength value (110.8 kJ/m2) was found in 5-layerseastern beech samples reinforced with carbon fiber fabric and bonded with PUR glue and the highest shear strength value (12.3 N/mm2) in 3-layered eastern beech samples reinforced with steel wire mesh and bonded with PUR glue
Logs of Betula ermaniiCham. were heated at a temperature inside the logs of 80°C for different heating durations of 0, 20, 40, and 60 h using a laboratory oven. After heating treatment, several wood qualities were examined, including residual stresses, moisture content, wood color, and physical and mechanical properties. The effects of the heating treatment duration on wood quality were analyzed using linear mixed-effect modeling. The developed models revealed that heating treatment affected residual stresses and wood color but not mechanical properties. The obtained results also suggest that a heating treatment duration of 20 h is sufficient to reduce residual stresses in B. ermaniilogs without reducing the physical and mechanical properties of wood
The propagation velocity models were built using AE sensors to capture stress wave on pine specimen surface.On the different specimens, cracks were made in different numbers and the depth was gradually increased from 0 mm to 90 mm at 10 mm intervals. AE experiment was combined with COMSOL to investigate propagation path.The results show that R-squared is 0.996 when fitting tangent of angle to propagation velocity.At smaller crack depths, stress wave is diffracted around crack tip and then continues to propagate in to sensor along a straight line.However, as the crack depth increases, the reflected wave at the end face will arrive at the detection location faster with significantly weaker diffraction.The area with dimensions of20×10 mm was identified about the crack tip by crack identification method
The angle to the grain has a significant influence on timber bearing strength. As the grain angle increases the bearing strength decreases. The aim of this research was to obtain the dowel bearing strength of the red meranti (Shorea spp.) timber at an angle to the grain. The scope of this research was as follows the specimens were made according to ASTM D143, the grain angle ranged from 0° to 12°, and the dowel bearing tests were displacement controlled in accordance with ASTM D5764. Results of this research was an empirical equation of dowel bearing strength (in MPa) in terms of an angle to grain θ (in degrees) namely Fe = 32.74 - 4.701θ + 0.2064θ2. The importance of studying the influence of the grain angle to the dowel bearing strength for timber connection design is because the direction of the timber grain is not perfectly 0°
WOOD RESEARCH Volume 69, Number 4
This study investigates the mechanical properties of three lesser-utilized timber species in Ghana: Blighia sapida, Gilbertiodendronlimba, and Lanneawelwitschii. Despite their potential, these species are underexplored compared to widely used commercial timbers. Six trees, two from each species, were tested for properties such as modulus of elasticity (MOE), modulus of rupture (MOR), compressive strength, shear strength, hardness, and density. Results indicate that Blighia sapida has superior mechanical properties, placing it in the D50 strength class, suitable for high-resistance structural applications. Gilbertiodendronlimba and Lanneawelwitschii are categorized under the D40 strength class, appropriate for moderate load-bearing uses. This research demonstrates that lesser-utilized species can serve as viable alternatives to traditional timbers, potentially reducing pressure on overexploited species. By promoting their use, the study supports sustainable forestry practices and contributes to a more diversified and resilient timber industry in Ghana
This paper presents an experimental and numerical investigation of two configurations of panels made of locally produced cross-laminated timber (CLT) with different orientations of laminations (boards) within transverse layers - conventional and modified orientation. Modified orientation refers to laminations of transverse layers positioned at an angle of ±45° in relation to longitudinal layers. The expected advantages of modified CLT are improved mechanical performance, more efficient use of resources considering material properties, reduction in variability of characteristics within the panels and increase in shear resistance. In addition to experimental testing, numerical analysis based on finite element method was performed and successfully validated in order to serve as a more efficient tool for CLT panel investigation and optimization
Scots pine (Pinus sylvestris L.) sapwood of 200 × 20 × 80 mm3 (L×R×T) was treated with both cell wall filling and lumen filling chemical agents (low-molecular phenol-formaldehyde, bio-oil, N-methylol/N-methyl compounds, sorbitol-citric acid, polysiloxane), which were fixed inside the wooden structure during heat-curing processes. The present study investigated the impact of the appointed chemical modifications on the surface characteristics of wood, which was addressed by measurements of the surface roughness (Ra), surface free energy (SFE), contact angles, wettability and its bonding quality. Independent of the chemical agents applied, Ra decreased as result of the chemical treatments, while SFE experienced a reduction. The Ra and SFE of both untreated and modified pine specimens increased after weathering processes. The weathering was appointed to cause a decrease in the equilibrium contact angle (θe) and an increase in the constant contact angle change rate (K-value). Increasing K-values after weathering for both untreated and modified pine specimens indicated their better wettability. Increasing wettability after weathering led to better adherence of acrylic paints on the surface of the Scots pine wood. In summary, the chemical modifications decreased the Ra and SFE of the pine sapwood, which may as a consequence affect the wettability and bonding quality…
Although anisotropic propagation behavior of acoustic emission (AE) in the sawn timber (ST) has been revealed, that in finger-jointed timber (FJT) is still less known.Therefore, a series of velocity and energy models of AE signalswere built as it propagates along different directions on the surface and inside of specimens (ST and FJT). At first, using polar coordinate system, velocity model in 36 directions was built in FJT, which was compared to ST.Furthermore, a continuous sine wave with a frequency of 165 kHz was selected as AE source to explore the energy attenuation law in FJT and ST respectively.The results showed that there are significant differences in velocity models between FJT and ST.The wavefront in STwas regular elliptical, while that in FJT has a clear depression in perpendicular to grain direction.This feature becomes more obvious with the increase of distance when AE signal propagates inside the FJT.Inside the FJT,energy magnitude in STwas 3.00-7.37 times of that in FJT
In this study, therepressure (15, 22.5, 30 MPa) and two temperature (45, 60°C) of ScCO2dewatering were tested on Moso bamboo (Phyllostachys edulis) strips. The aim was to research the effects of these conditions on the dewatering rate, moisture distribution, and shrinkage of bamboo. The results showed that: 1)The first cycle discharges the most water of all drying conditions. The most effective dewatering time consisted of a 15 min depressurization period and a 5 min discharge period. 2)The ScCO2 dewatering rate of bamboo strips decreased with decreasing MC, with a maximum decrease of 78%.The maximum and minimum dewatering rates were 37.04%/h and 4.41%/h, respectively. The dewatering rate was synergistically affected by temperature and pressure, which increased significantly with pressure at 45°C, but was minimized at 60°C at 22.5 MPa. 3)After dewatering, the moisture distribution in the bamboo strips shows a trend of higher moisture content(MC) in the middle and lower MC on both sides in the tangential and radial directions. 4)Most of the bamboo strips produced shrinkage after the 1st cycle of dewatering, and the overall shrinkage in the tangential direction was greater than that in the radial direction. The maximum tangential and radial shrinkage rations are 3.06% (22.5 MPa/45°C) and…
This study investigatedtransverse shrinkages and wood density for Acacia auriculiformis trees from six clones planted in north-central Vietnam. Radial and among-clonal variations of partial and total shrinkages in tangential (respective to Tn and T) and radial (respective to Rn and R) directions, partial and total coefficient of anisotropy (respective to Tn/Rn and T/R), and basic density (BD) were examined. There were significant differences among clones for Rn and R, but no significant differences were found among clones for Tn and T. The lowest average Rn and R were detected in clones Clt18 and Clt26, suggesting that these clones might be more appropriate for breeding programs focused on improving shrinkage traits for sawn timber production. BD is not a good indicator for predicting transverse shrinkages. In contrasts, stress wave velocity measured in standing trees has the potential to be used as a non-destructive method for predicting the transverse shrinkage of A. auriculiformis planted in Vietnam
This study explores the innovative application of QGIS for mapping radial wood density variation across the entire cross-section of selected native and non-native forest species, aiming to enhance wood characterization. Using samples from Ochroma pyramidale, Acacia mangium, Eucalyptus grandis, and Pinus sp., we applied X-ray densitometry to obtain high-resolution images, which were then analyzed with QGIS to create detailed density maps. These maps provided a clear visualization of radial density variation, offering insights into the internal structure of the wood. The integration of QGIS with X-ray densitometry proved to be an effective tool for assessing wood density variation, supporting more precise and sustainable forest management practices
Volume 68 (2023)
WOOD RESEARCH Volume 68, Number 1
Syzygium album is a critically endangered species, and the wood basic properties haven’t been reported. Therefore, this paper analyzes the wood from the anatomical characteristics, physical properties, and secondary components. The results showed that observed S. album wood of a 46-year-old tree is diffuse-porous to semi-diffuse-porous wood. The maximum vessel tangential diameter is 127.47 μm, which is found at the beginning of the earlywood. The wood rays are heteromorphic type I and II, and the multi-column part is mostly 3 cells wide. In physical properties, the air-dry density is classified as "heavy", whereas its air-dry and full-dry differential dry shrinkage are "small" and "medium", respectively. This indicates that the wood performs better when dried. The content of benzene-ethanol extract from S. album wood is 2.10%. The benzene-ethanol extracts were analyzed by GC-MS, and the main components are 2,6,11,15-tetramethylhexadecane (3.29%), eicosamethyl cyclodecasiloxane (10.02%), octadecamethyl cyclononasiloxane (7.43%), and tetracosamethyl cyclododeca- siloxane (3.60%), etc.
Four kinds of environmental anti-mildew agents (boric acid/borax, 3-iodo-2-propynyl-butyl-carbamate (IPBC), sodium tetrafluoroborate/didecyl dimethyl ammonium chloride (NaBF4/DDAC), tebuconazole) were used to treat bamboo with different concentrations respectively. The optimal concentration of each anti-mildew agent and the comparison of the anti-mildew capacity were evaluated with Aspergillus niger, Trichoderma viride and Penicillium citrinum, respectively. The results showed that the optimal anti-mildew agent concentrations of boric acid/borax (F1), IPBC (F2), NaBF4/DDAC (F3) and tebuconazole (F4) were 3.0%, 1.5%, 0.5% and 0.4%, respectively, and the average control efficacy of the three test molds was 73.15%, 92.03%, 88.43% and 98.67%, respectively. The order of anti-mildew capability of these four anti-mildew agents with their optimal concentrations was F4 > F2 > F3 > F1.
The purpose of this research is to determine the orthotropic material properties of the Norway spruce (Picea abies) and to develop a finite element modeling technique that, when applied to an individual specimen, can properly predict the outcome of the measurement results (i.e., deflection by a predefined loading) by simulation only. For the development of the finite element model of timber beams, their unique annual ring pattern is considered. The HSV color spectrum of picture of the end grain pattern is analyzed with a photo analytical algorithm in order to separate the phases, earlywood and latewood. The determined surface ratio of the phases is used to hypothesize that the volume and surface ratios are equal. For the description of wood as a material the rule of mixtures is used. The results of the compared measurements and FE models based on the introduced hypotheses show good agreement within the linear elastic limit.
The research was based on the analysis of the density, bending strength and modulus of elasticity of 100 oak lamellae generated as small-sized production waste. In this part of the study series, the test results were presented in detail and analysed, in particularly the density distribution. Correlations between some test results have been shown. The dynamic and static test results were also compared. Despite the poor quality lamellae, the average density of the sample set corresponds to literary values and the distribution of density is normal. Specimens with low density are unsuitable for further use. But the density alone cannot be used for classification. Between static and dynamic modulus of elasticity can be found a good relationship. The relationships between density and both static and dynamic modulus of elasticity of the specimens can be considered as good, too. The best correlation is in bending tests between the deflection of the specimens in the elastic range and the bending strength.
The aim of the research was to determine the changes in susceptibility of Scots pine (Pinus sylvestris L.) wood to feeding by subterranean termites Reticulitermes lucifugus var. santonensis conducted in accordance with the ASTM D 3345-08: 2009 The sapwood after modification in furfuryl alcohol at concentration 50% with the addition citric acid at concentration 1%, natural sapwood and heartwood experiment as a compulsory reference material were used for the tests. The blocks of Scots pine wood were used to create seasoned samples of 7% ± 1% moisture content. The blocks with dimensions of 25.4 x 25.4 x 6.4 mm were made from three trees. Each variant was represented by 5 blocks. All wood blocks were freeze-dried before starting the experiment in order to measure the dry weight. After 4 weeks of termite feeding visually rates of wood destruction were: 9 (light attack) for modified sapwood, 2.8 (heavy attack/failure) for natural sapwood and 8.2 (light attack/moderate attack) for natural heartwood. The loss of wood weight of blocks was: 0.01 g for modified sapwood, 0.071 g for natural sapwood and 0.21 g for natural heartwood. The mortality of the termites in the case of modified sapwood was complete. The termite mortality in…
This research aims to address the noise pollution by developing an acoustic absorber made of polylactic acid (PLA)/polyhydroxyalkanoates (PHA)-wood fibers (PLA/PHA-WF) by compression molding (CM) and additive manufacturing (AM). Physical, mechanical, thermal, water absorption, and biodegradation properties of the developed acoustic absorbers by CM and AM were characterized and compared. Upon providing an air gap, thin absorbers developed by AM exhibit an increased and narrow acoustic peak than the CM absorbers because of the Helmholtz resonance effect due to the decreased density and increased porosity in the AM absorber. The results also show that the mechanical and thermal properties of the absorbers developed by CM and AM were almost similar and absorber developed by AM shows an increased rate of water absorption and biodegradation compared to absorber developed by CM due to the presence of porosity in the AM structure.
Wood-based composites with different ratios of wood fiber (WF)/palm kernel shell (PKS) and polyurethane (PU) content have been prepared using the wet-process method. Samples of WF85/PKS15 and WF75/PKS25 were fabricated where each sample was applied with 20% and 70% of PU contents and its physical and mechanical properties had been studied. The physical results show that the samples with 70% of PU content were denser, had low porosity, low moisture content, and low water absorption. Surface morphology observation shows both series samples with high PU content tend to form tube-like shape with different diameter. In mechanical studies, generally, the sample with high PKS and PU possesses high flexural strength, flexural modulus, tensile strength, tensile modulus, and hardness. However, the increased of PKS content in the composite reduces the tensile strength for both samples with 20% and 70% of PU. The effects of the binder and palm kernel shell in the composite were also explained. Based on the Japanese Industrial Standard (JIS) A 5905 standard, the sample composites meet the requirement under medium density fiberboard (MDF) category and classified as board type 5 which suitable as furniture, house, and automotive interior design and construction materials.
The study investigated morphology and thermal properties of cellulose/poly furfural alcohol (PFA) composites prepared from maize stalk through acid mixtures. The cellulose nanocrystals (CNCs) were extracted from maize stalk via acid hydrolysis using mixtures of various acids. The prepared CNCs were encapsulated in a PFA matrix via in situ polymerization process using p-toluene sulfonic acid as catalyst. The properties of untreated maize stalk, cellulose and their nanocomposites were analysed by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transmission infrared (FTIR) and thermogravimetric analysis (TGA). The crystallinity of maize stalk was generally increased after an acid hydrolysis dominated by H2SO4/HNO3 and H2SO4/HCl. The same trend was observed from TGA, except that H2SO4/H3PO4 and H2SO4/HClO4 dominated thermal stability trailed by H2SO4 hydrolysed CNC nanocomposite. The surface breakage of fibers observed in SEM images was depended on the strength of acids used to hydrolysed the CNC. There was also evidence of aggregation and cracked PFA surface with addition of acid hydrolysed CNCs, dependent on the acids strength. The H2SO4/HClO4 hydrolysed CNC/PFA displayed a fairly good dispersion of CNCs in the PFA matrix with no surface breakage.
To explore the propagation law of AE signal in wood, the propagation velocity of P-wave and S-wave and the energy attenuation law of different frequency components were studied By PLB (pencil-lead break) tests. Firstly, an improved time-difference-of-arrival (TDOA) method was designed to determine the arrive time. The propagation velocities of P-wave and S-wave were calculated. Then, the Young's modulus was estimated by P-wave velocity. Finally, on the basis of eliminating the influence of standing wave, the energy attenuation models were obtained by numerical fitting and wavelet decomposition. The results showed that the improved TDOA algorithm can calculate the propagation velocity of P-wave and S-wave at the same time through one test, and the P-wave velocity can be used to estimate the Young's modulus. P-wave propagated faster in soft wood, while S-wave propagated faster in hard wood. The higher the frequency of AE signal, the faster the energy attenuation.
This study examined the performance of beech and self-tapping screw composite dowel applied to non-extruded L-shaped member joints and carries out theoretical calculation and analysis of stiffness. The test results indicated that eleven specimens showed three failure modes. It was found that the composite dowel had different degrees of bending phenomenon. The failure modes were also proved by the finite element analysis. Since the spruce-pine-fir was in the middle of the L-shaped specimen set in this test, it can rotate around the geometric center composed of four composite dowels.
The objectives of the study, conducted in the National Park of Bou Hedma, were to examine: (1) the relative contributions of short-term canopy (STE) and long-term soil effects (LTE) of a shrub species in explaining differences in biomass, species diversity (richness) and species density of understory plants (i) between shrubs and open areas, (ii) between shrubs and removed shrubs; and (2) the role of grazing in driving changes in direction of short-term and long-term effects in shrub/understory species interactions. We measured environmental conditions (soil nutrients and soil water) in plots that represented different neighborhood conditions (in open areas between shrubs, amongst intact shrubs and among removed shrubs), which were either fenced or exposed to grazing by large herbivores. We also studied understory species biomass, richness, density survival rate of a target species in plots represented different neighborhood conditions. Differences in species richness, density and biomass of understorey communities between shrub removed and open areas were mostly due to long-term soil effects whereas differences below shrubs and shrub removed were due to short-term effects in particular on soil water content. Our study provides additional evidence that savannas shrubs have the potential to increase the diversity of arid systems at the landscape…
To study the effect of retention and drainage aids on the fast-growing eucalyptus bleached kraft pulp (EBKP) suspensions, different concentrations of cationic polyacrylamide (CPAM) and cationic starch were dosed with EBKP suspensions and their effects on rheological properties were studied. The shear yield stress (τy) of softwood bleached kraft pulp (SBKP) and poplar alkaline peroxide mechanical pulp (PAPMP) were compared and evaluated for their potential applications. The results show that in the steady-state shear condition, the τy of EBKP is proportional to the pulp mass concentration (Cm), corresponding to the exponential relation . SBKP had the highest τy values, followed by EBKP and PAPMP. Adding CPAM and cationic starch to EBKP suspensions at low to moderate doses increased the τy, but once the levels reached a certain point, the τy values began to deteriorate. This research is crucial to achieve optimally and stabilize the downstream manufacturing process in papermaking.
This work assessed how to remove lignin of palm oil empty fruit bunch (EFB) in environmentally friendly method and less energy. Moreover, delignification was strengthened with additional H2O2 to perform hydroxyl radical by microwave radiation in low NaOH solution of concentration up to 0.8 M, 10%. Setting on microwave, solution was heating up and cause delignification work more effective. Observation at black liquor showed that temperature was influence by microwave radiation duration while NaOH concentration affected total suspended solid increasing. Optimally treated EFB at 0,2 M NaOH with effective lignin removal and holocellulose increasing reached 27% and 26%, respectively. Unfortunately, at higher NaOH concentration, the decomposition penetrated EFB interior, holocellulose and made lignin percentage high again. Therefore, EFB yield got less at higher NaOH concentration because more EFB was sludgy and lost during washing. XRD analysis showed the increasing crystallinity by 2.2%, closer to -cellulose. SEM showed successful impurities removal from EFB surface and Ca, Nb, Si, and Mg detected by EDS.
The effect of antenna design modification, paper substrates and relative electrical permittivity of background materials on the reflection coefficient of UHF RFID antennas was studied. Simulation software was used to modify the design and calculate the reflection coefficient of the antennas. By modifying the coupling of the dipole with the induction loop of the antennas, a reduction of the simulated reflection coefficient was achieved compared to the commercial antenna. The positive effect of antenna modification was also confirmed by measuring the reflection coefficient of antennas printed on paper by thermal transfer printing, placed on extruded polystyrene and particle board. The reflection coefficient of the modified antennas was lower when placed on extruded polystyrene, whose relative electrical permittivity was lower than particle board. After installing the memory chip to the antennas printed on paper and paperboard, the identification, reading and recording range of passive UHF RFID tags were measured after they were placed on thicker paperboard, extruded polystyrene and particle board. The positive effect of antenna modification on improving the communication quality of passive UHF RFID tags placed on background materials with a relative electrical permittivity of 2.4 to 6.7 was confirmed.
The addition of green tea leaves fractions < 0.315 mm as a filler to urea-formaldehyde resin to reduction of emission of formaldehyde from three-layer birch plywood was investigated. Moreover, other properties such as bonding quality and water resistance of plywood were investigated. It was found that green tea had an ability to absorb formaldehyde. This phenomenon was caused by phenolic compounds contained in green tea leaves. The addition of green tea in the amount of 20% and 25% resulted in a decrease in formaldehyde emission from plywood comparing to the reference sample. The bonding quality test showed that the addition of tea leaves as a filler did not affect the strength properties of the tested bond lines.
WOOD RESEARCH Volume 68, Number 2
This paper analyzed the length, width, and location of shakes in the air-drying process of larch log (Larix principis-rupprechtii Mayr) 1 m long and 66% initial moisture content. The development law and distribution characteristics of shakes during log drying of larch were studied and shake generation and development law were analyzed from two aspects of microstructure and growth defects. The variation of dry shrinkage deformation along the radial direction and knot influence on it was analyzed using the split-shaped stress test strips. At the cellular level, the cell wall shrinkage behavior of heartwood and sapwood and the microstructure of knots were observed. The results showed a significant relationship between eccentricity and shake distribution; the IIa region is the most prone to dry shake. The evolution of shakes is closely related to the drying rate. In the high-speed drying stage (MC ≥ 40%), shakes almost do not occur; in the decelerating drying stage (40% ≥ MC ≥ 20%), the amount, length, and width of shakes increase rapidly. In the low-speed drying stage (20% ≥ MC), the area of shakes tends to stabilize or even decline. The main reasons for dry shaking are the dry shrinkage difference between tangential and radial cell…
The 3 mm thick oak veneers were discolored by single ions of Fe2+, Cu2+, and Mn2+ and mixed ions of Fe2+-Cu2+, Fe2+-Mn2+, and Cu2+-Mn2+. The brightness (L*), red-green index (a*), and yellow-blue index (b*) of the veneers changed by varying degrees with the changes in ion mass fraction, temperature, heating time, ion species, and ion mass fraction ratio. The maximum values of total color difference (△E*) of the veneers were 38.94, 11.79, and 9.42 for Fe2+, Cu2+, and Mn2+. Moreover, the total color difference (△E*) values of 24.07, 13.71, and 4.45 were observed for Fe2+-Cu2+, Fe2+-Mn2+, and Cu2+-Mn2+ mixed ions. The veneers showed different degrees of vibrational peaks after discoloration. According to the ultraviolet spectrum, Fe2+ had a red shift in the ultraviolet absorption band of the unsaturated carbonyl compound and benzene ring compound. Moreover, the dark effect of Fe2+, Fe2+-Cu2+, Fe2+-Mn2+, Mn2+, Cu2+-Mn2+, and Cu2+ gradually decreased. The surface of the veneer was flat, without any rupture or deformation, and the pores were clear after treatment.
Leucaena leucocephala stem bark that was eleven years old was studied for its chemical composition and usage. The samples were subjected to chemical analyses based on ASTM standard procedures after being air-dried for several days. The results found that the bark of L. leucocephala has a pH value of 6.04 and that the solubility of the bark in 1% NaOH alkali is the highest compared to the solubility in hot water (14.45%) and cold water (14.36%), while the chemical composition of the bark of L. leucocephala was ash (15.76%); extractives (8.39%); holocellulose (132.85%); hemicellulose (103.66%); cellulose (29.19%) and lignin (38.24%). Based on the findings, L. leucocephala bark was less acidic. When used as a source of carbohydrates, bark has a high solubility, and its chemical composition may have an impact on how quickly it burns when it is pyrolysed.
Water retention after 2 hours and 24 hours of soaking in water was determined for beech shavings subjected to heat treatment at temperatures of 120°C, 140°C and 160°C for 2 hours, 4 hours, 6 hours and 8 hours in order to reduce the equilibrium moisture content (EMC) of the wood shavings for use in wood based composites. EMC was determined after 14 days of air conditioning at 23°C and 55% relative humidity. The measured values were compared with the sample dried at 103°C. Water retention was determined after 15 min of centrifugation at 1400 rev.min-1 for a more objective assessment of the wood's ability to retain water in the cell lumens. The results showed that heat treatment reduces the EMC of beech shavings heat-treated at 160°C for 8 hours in the given conditions from 8.7% to 6.19%. The reduction of EMC at lower temperature was not sufficient enough, especially in the shorter treatment duration of up to 6 hours. In parallel, the reduction of water retention from 65.53% to 47.79% was caused by heat treatment for 8 hours at 160°C.
In this study, the Scots pine wood samples were impregnated (single treatment) with boric acid combined with two types of water-based acrylic resin (pure acrylic and semi-translucent acrylic emulsion) to limit the boron leaching and improve the decay resistance. The results showed dimensional stability in anti-swelling efficiency and water absorption improved in wood specimens treated with boric acid and acrylic types. While the leachability was over 90% for only 3% boric acid-impregnated wood (control), it was calculated at 36% for acrylic emulsions-impregnated wood. Although there were no weight losses for the unleached woods, it was up to 9% for leached woods impregnated with acrylic resin and emulsion. The 25% acrylic emulsion had no weight losses after the leaching test for Coniophora puteana and Trametes versicolor. The boric acid combined with acrylic resin can improve the leaching resistance with the synergic effect, enhancing resistance against biological threats.
This study assessed the quality of birch, beech, and oak for timber production on former agricultural land. All sample plots for the selected species had the same forest habitat type. All measured trees had already reached the age of felling. Thus, beech was over 120 years old, birch was over 70 years old, and oak was over 140 years old. On each plot, the same morphological features were measured for all trees: diameter at breast height, tree height, height of the first dead branch, height of the first live branch, and crown base. Based on collected data the length and percentage of the trunk suitable for industrial purposes were calculated. In general birch and beech trees from former agricultural land were higher, but had thinner trunks, when in oak reverse observation were noticed. Tree trunks from former agricultural lands have app. 7% shorter knots-free trunk section. The bigger different between forest and former agricultural land was noticed in case of the oak – 14%, then beech – 5% and birch – 1%. Considering the morphological characteristics of the trees and quality indicators, we showed that all species could be used for the afforestation of former agricultural lands to produce high-quality…
To improve the permeability of dye solution in wood, poplar was pretreated by freeze-thaw cycle. The effects of three parameters, such as freezing time, thawing time and circulation times on the dyeing effect of pretreated poplar were investigated by single factor method. On this basis, pretreatment conditions were optimized by response surface methodology. The optimum conditions of this treatment were freezing time of 11.9 h, thawing time of 7.2 h and two cycles. Under these conditions, the dye uptake and chromatic aberration of the treated wood were 25.77% and 21.14%, respectively, which were close to the theoretical predicted values. The results showed that freeze-thaw cycle pretreatment could effectively improve the permeability of poplar and enhance the dyeing effect of wood.
The aim of this work is to propose the first model hypothesis and function for predicting the efficacy of deacidification. We have used the dDEA as the first basic factor influencing the efficacy. The resulting relationship is based on the best achieved reliable η data and related dDEA data, from mass deacidification technologies used for the lifetime and usability increase of millions of books, historical documents worldwide. The resulting η predicting function is as follows η = 0.732984+0.125612*dDEA^(-0.214237). This first 1D function can serve as an impulse for continuing improvement of the prediction, and 2D, 3D and multidimensional models. It can be used for comparisons and connecting η with η-characteristic mechanical, physical, cellulose solution properties; the prediction can serve for continuing improvement of efficacy of the conservation technology in increasing the paper carriers of information, documents longevity and usability.
In this article, red and blue ink handwriting on aged paper was fixed by fixative to prevent handwriting from fading or diffusion during aqueous deacidification. Firstly, four fixatives were selected: polydimethyl ammonium chloride (PDDA), the quaternary ammonium salt of chitosan (HACC), cationic guar gum (CGG), and benzyl triethyl ammonium chloride (TEBAC) alcohol solution, according to their fixation effects on filter paper dyes, and derive the optimal composition ratio of the above four fixatives. Experimentally derived that PDDA has an excellent fixation effect on red ink handwriting, and HACC has an excellent fixation effect on blue ink handwriting. In addition, HACC also has a positive impact on the conservation of handwriting in real archives. The mechanical properties of aged paper were improved, and the paper fibers had no obvious change after the fixation and deacidification processes.
In this paper an efficient procedure for obtaining a cohesive law for Mode I timber fracture (crack opening), based on the Double Cantilever Beam (DCB) tests is given. DCB tests were performed on ten European spruce specimens in order to determine the energy release rate vs crack length (R curves). Two crucial parameters - crack length during the experiment and the crack tip opening displacement were obtained using 2D Digital Image Correlation (DIC) technique. In order to determine accurate fracture resistance (R curve), procedure which includes calculating cumulative released energy was employed. The cohesive law for Mode I fracture of wood was obtained by differentiation of the strain energy release rate as a function of the crack tip opening displacement. This cohesive law is further implemented in the successful numerical modelling of failure modes in large-scale end-notched glulam beams which were experimentally tested in four-point bending configuration.
In this paper, the plywood obtained from dismantling discarded furniture was selected as pyrolysis experimental materials. Pyrolysis was performed at a heating rate of 100°C/h, 150°C/h and 200°C/h and pyrolysis temperatures of 400°C, 500°C, and 600°C to evaluate the effects of pyrolysis process on products yield and the products features. The results show that the yield of solid products gradually decreases with the increase of pyrolysis temperature and heating rate while liquid products and non-condensing gases' yield gradually increases. The carbon content in solid products reached 80.76 - 94.35%. Carbon content gradually decreases with pyrolysis temperature, but the proportion of C/H and C/N gradually increases. The pyrolysis solution is weakly acidic due to the adhesives in pyrolysis material.
This study was conducted to investigate the applicability of wood bark-based activated carbon (AC) for the adsorption of metal ions and volatile organic compounds (VOC) from the atmosphere. Contents of Fe and Al in the AC made with coconut shell, and the bark of larch and cork oak (CSA, LBA and COA, respectively) were higher than those of the unexposed AC and increased with the exposure to various indoor/outdoor spaces when compared to the unexposed AC. However, Fe and Al contents of the exposed AC, which is a coal-based one used as a control (SAA), were lower and scarcely higher than the unexposed SAA. From the results, it is evident that the wood bark-based AC examined in this study is more effective to adsorb metals than SAA. The SEM-EDS analysis exhibited prominent metal-adsorptivity of COA, although its total surface area and pore volume were lower than those of SAA. Total VOC-adsorptivity was the highest in COA followed by CSA, CBA (cypress bark activated carbon), LBA and SAA. In conclusion, wood bark-based AC can be utilized as an effective adsorbent for the removal of metals and VOC from the atmosphere. The optimum AC is COA, an industrial by-product, in view of…
On the basis of a single-factor experiment, a mathematical model was established by the response surface analysis method based on the Box-Behnken experimental design principle. The effects of three factors, including hot-pressing temperature, hot-pressing time, and hot-pressing pressure, and their interactions on the modulus of rupture (MOR) of Metasequoia-based three-layered structure parquet flooring were studied. The results show that the quadratic polynomial model in the regression equation is significant, and the correlation between the value predicted by the model and the experimental value is 91.17%. The optimized best hot-pressing process parameters are determined to be as follows: hot-pressing temperature of 96.03°C, hot-pressing time of 6.70 min, and hot-pressing pressure of 8 kg·cm-2. Under these conditions, the best MOR are obtained, reaching a value of 102.05 MPa. The theoretically predicted value is in good agreement with the experimental results.
Microwave heating is a new type of pre-heating for fiberboard mats. Compared to conventional heating, microwave heating is faster and the surface and interior are evenly heated, thus avoiding the phenomenon of premature hardening of the surface layer of the fibreboard mats. In this paper, the heat transfer law of microwave preheated fiberboard mats was analyzed, and a thermodynamic model of fiberboard microwave heating was established. Furthermore, a microwave preheating simulation was established through COMSOL software; the temperature distribution of the fiberboard after microwave heating was analyzed and the reliability of the simulation model was verified through experiments. The temperature changes of fibers in the two preheating methods were compared by direct contact preheating experiment and microwave preheating experiment. Microwave preheating is more efficient than direct contact preheating, and more uniform temperature distribution in fiberboard mats. The core layer temperature is higher than the surface layer temperature, which can shorten the preheating time. By comparing the COMSOL model with the test, the model can basically reflect the temperature change law of microwave preheating, and the temperature of each layer of the slab is more uniform in the model simulation process. The heating law of the fiberboard was obtained, which provided…
This study is interested in isolating fungi from the wood parts of cedar trunks withered and identifying these lignivorous fungi. A sample was isolated from the cedar grove of Tazekka National Park located south of the city of Taza in Morocco. The culture and purification of the isolated fungus were done on a water agar medium and then on a PDA medium. After the purification of the fungus, a morphological study by scanning electron microscope allowed us to identify the pathogen Paecilomyces. A molecular characterization identified Paecilomyces maximus with a coverage percentage of 99% and an identity of 98.77%. To our knowledge, this is the first report of P. maximus in decayed cedar wood.
WOOD RESEARCH Volume 68, Number 3
The chemical composition and variations in chemical structure of hemicellulose in earlywood (EW) and latewood (LW) of two individual Japanese cedar trees (C-Boka and T-Boka) were investigated. The trees were cultivated under different growth conditions: C-Boka grew slowly in a forest, while T-Boka grew rapidly in a location rich in nutrients and sunshine. For the chemical structure of hemicellulose, arabinoglucuronoxylan (AGX) showed varied side-chain substitution rates with glucuronic acid and different molecular weights in the transition between EW and LW. In contrast, the fundamental composition of glucomannan/galactoglucomannan (GM/GGM) was relatively unchanged between EW and LW. The modification of AGX and GM/GGM from EW to LW differed between C-Boka and T-Boka and might be influenced by the growth rate of the trees.
This research deals with low molecular weight-phenol formaldehyde (LMW–PF) impregnation on sepetir (Sindora spp), nyatoh (Palaquium spp.), and pisang putih (Mezzettia spp.) woods to determine the effect of different anatomical structure on weight percent gain and dimensional stability improvement. The wood samples were impregnated using LMW–PF solutions with 7, 8, 9, 10, and 11% of concentrations (w/w), vacuum-pressured (–98 kPa, 15 min, 350 kPa, 4 h), and re-immersed in 80°C for 3 h. According to the findings, LMW–PF impregnation reduced coefficient of swelling by 9.64–29.95%, and increased anti-swelling efficiency by 12.24–29.91%. Additionally, the water absorption and thickness swelling reduced by 2.43–38.75% and 15.94–34.21%, respectively, indicating the improvement of dimensional stability. Microscopy and NIR analysis revealed the presence and reaction of LMW–PF within porous wood matrix. The effect of diverse anatomical structures caused complexity on LMW–PF impregnation. Sepetir-treated wood with fewer anatomical barriers resulted in better dimensional stability improvement than others.
In this study, the changes in bending strength were investigated by applying heat-treatment to laminated beams modified with acorn tannin to improve the mechanical properties of wooden load-bearing structural members. For this purpose, acorn tannin was impregnated on samples prepared from Scotch pine (Pinus sylvestris L.), oak (Quercus petraea L.), and chestnut (Castanea sativa Mill.) woods. Heat treatment was applied to the samples impregnated with acorn tannin at 150ºC for 3 hours. Untreated, heat-treated, and tannin-modified samples were conditioned until they reached constant weight at 20ºC at 65% relative humidity (RH), 40ºC at 35% RH, and 10ºC at 50% RH. Bending resistance tests were applied to the elements that are conditioned in outdoor conditions according to ISO 13061-3. The results of bilateral interaction between tree species and treatment type were compared, the highest bending strength increase was found in Scotch pine samples by 5% compared to control samples.
This study aimed to investigate the relationship between surface roughness and anatomical features of wood in 15 different species of boards. Surface roughness was measured parallel and perpendicular to the wood grain using a surface profilometer, and anatomical features such as pore size and distribution were analyzed using microscopic techniques. The results showed that surface roughness perpendicular to the grain direction was consistently higher than that parallel to the grain direction for all wood samples. This difference in roughness was correlated with pore size and density. It shows that the larger pores and lower density lead to higher roughness perpendicular to the grain. The study also found that traditional hand planning methods (push and pull) produced a smooth surface finish, with no statistical differences in roughness.
Process parameters play an important role in wood surface densification. In this study, the poplar (Populus tomentosa Carr.) wood was heated on one side at 100℃, 150℃ and 180℃, and compressed in the radial direction with the speed of 10 mm/min. The initial thickness of the wood samples were 30 mm, 26 mm and 23 mm, and they were all compressed to 20 mm and resulting in three different compression ratios: 33.3%, 23.1% and 13.0%. When the surface densification completed, the density distribution and hardness of the densified and un-treated samples were measured and analyzed. Results show that the compressing temperature mainly decided the formation of the density distribution curve and the peak density increased with the increasing temperature; as the compression ratio increased, the peak density increased and the thickness of the densified zone broadened; the surface hardness was highly correlated with the density distribution which was affected by temperature and compression ratio, and as the peak density increased and the thickness of the densified broadened the hardness increased accordingly. Therefore, by optimizing the process parameters such as the compressing temperature and compression ratio could generate a targeted density distribution which has the desired hardness.
The behavior of the wood flour-polypropylene composites prepared with various contents of untreated and silane-treated wood flour by immersion in water was studied, as well as the effect of the water absorbed by the samples on their mechanical properties. The highest degree of water absorption was observed for the composites containing 30 – 50 mass% alkali pre-treated wood flour. For the materials with 50 mass% untreated, silane-treated and alkali pre-treated wood flour, the water absorption measured was 8.76%, 7.84% and 13.91%, respectively, after 15 days immersion in water. The value of the thickness swelling calculated for the samples prepared with 50 mass% silane-treated wood flour – polypropylene was the lowest – 1.29%. It was proved that the absorption of water molecules results in change of the tensile profile of the thermoplastic polypropylene composites filled with hygroscopic filler.
In this experiment, poplar fibers containing 0%, 2%, 4%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 25% and 30% of urea-formaldehyde resin were prepared. A model for the detection of urea-formaldehyde resin content in poplar fibers was established by the hyperspectral near-infrared imaging system combined with relevant algorithms. The spectral images of poplar fibers containing different contents of urea-formaldehyde (UF) resin were measured separately using hyperspectral imager. The results of four preprocessing methods, namely mean centering (MC), multiple scattering correction (MSC), standard normal variables (SNV) and first-order derivative (1-Der) were analyzed, and the optimal preprocessing method was selected as SNV. The band combinations with the highest correlation with the urea-formaldehyde resin content were compared and analyzed with the full-band model to establish the partial least squares regression (PLSR) model. The experimental results show that the hyperspectral imaging system combined with the corresponding algorithm can achieve rapid detection of UF resin content in poplar fibers, and the results of this study provide technical support and theoretical reference for determination of resin content in ultra-thin fiberboard production. The method is an innovative model for the determination of UF resin in wood fibers.
Cross-laminated timber (CLT) CLT is an excellent material for building and high load-bearing structural applications, but its fabrication and use are limited to softwood only. The suitability of aspen (Populus tremula L) wood for manufacturing CLT was assessed by using two adhesives, one-component polyurethane (1C-PUR) and melamine adhesive (ME). Physical properties like water absorption (WA), thickness swelling (TS), delamination, and mechanical properties like bond shear strength, bending modulus of elasticity, bending strength, and rolling shear strength were evaluated to examine its suitability. Compared to ME-bonded CLT, 1C-PUR bonded CLT panels displayed superior physical characteristics, with 70% passing the delamination test. CLT panels bonded with 1C-PUR adhesive also have better mechanical properties than ME-bonded CLT. CLT panels experienced three types of bending failure: rolling shear, delamination, and tension. Aspen CLT has similar or higher mechanical properties than traditional softwoods, making it suitable for CLT manufacturing.
To obtain the mechanical properties of plywood produced from six yearold hybrid Eucalyptus in Ghana was the objective of this research. The samples for the experiment were prepared and tested according to GS EN 326-1, GS EN 310, GS EN 314-1, and GS EN 314 -2. The data obtained were analysed using the factorial ANOVA analysis. The mean results obtained for the various treatments were MOE (6520 – 7638 N/mm2), MOR (53.29 – 60.56 N/mm2, shear strength (2.47 – 5.51 N/mm2), failure (72 -90%) and density (725 – 748 kg/m3). The orientation of the surface veneer caused variations among treatments whiles the adhesives PF and MUF largely did not cause any variations among treatments. This study has proven that it is possible to produce sufficiently strong and resistant plywood from the juvenile wood of eucalyptus.
This study is the continuation of the first part (Horváth et al. 2023), in which density, bending strength and modulus of elasticity of 100 oak lamellae generated as small-sized production waste were investigated. In this part of the study series, the classification of our sample set is carried out according to the EN 338. A visual pre-grading is presented, to remove the worst specimens and achieve a better final result and a standardized visual grading is also shown. Our results are compared with literature values of clear specimens as well. Amount of 80% of the specimens were found to be suitable for further structural use. The total sample set is classified in strength class D35 (average density 712.6±72.5 kg/m3; average MoRadj 65.4±16.2 MPa; average MoEadj 13.4±3.1 GPa), while the visually pre-graded part with better average test results is classified in strength class D45. Industrial wood residues contain a sufficiently high proportion of elements for further processing, so that after sorting it can be used as raw material for glued-laminated load-bearing timber.
Since the methods based on the interaction of a relatively low intensity flame on the lignocellulose sample surface often do not allow measuring the heat release rate (HRR), a procedure using oxygen consumption calorimetry was proposed. The method was applied to OSB samples with dimensions of 320 mm x 140 mm x 25 mm placed in a vertical position. During the measurement, in addition to the HRR, the production of smoke, which was significant after stopping the burner, was also monitored. The average net value of HRR at burner outputs of 3 kW, 4 kW and 5 kW was 2.339 kW and the smoke specific extinction area was in the range of 10.88 m2.kg-1 and 13.19 m2.kg-1.
The purpose of this research is to test Norway spruce specimens with different growth ring orientations weakened by edge-notch until failure. In the experiments the specimens were subjected to 3-point bending, tension and compression tests. In addition, failure mode during loading is investigated using a high-resolution camera. Based on the measurement results the correlation between latewood ratio, ultimate force, ultimate elongation/deflection, calculated moduli, growth ring orientation and diameter of the growth ring at the edge-notch were obtained. Based on the population data of the three tests conducted, only one parameter pair, namely the ratio of latewood to calculated modulus, influences the measurement results to almost the same extent. The other parameter pairs show different values and correlations.
The aim of this study is to investigate the effect of using vermiculite on the thermal, physical and mechanical properties of cement-bonded particleboards. For this purpose, single-layer cementitious particle boards with a final density of 1200 kg/m3 and a size of 550 x 550 x 10 mm were produced using 2 type vermiculites (crude and expanded) at three different ratios (5%, 10% and 15%). The produced boards were examined in terms of thermal (TGA/DTG), physical (moisture content, density, water absorption and thickness swelling), mechanical (modulus of rupture, modulus of elasticity, internal bond strength and screw withdrawal resistance) properties. According to the TGA results, using both types of vermiculite caused an increase in cement hydration products in the boards and increased the thermal resistance. While the use of vermiculite did not significant effect on the density and moisture content of the boards, it increased the dimensional stability of the boards. The values of modulus of rupture and modulus of elasticity increased when the low amount of vermiculite was added. However, with the use of vermiculite in the boards, there was a decrease in the internal bond strength and screw withdrawal resistance values in general. All boards produced using vermiculite met the…
In this study, pulps of the species Bambusa vulgaris and Dendrocalamus asper were produced through the chemi-thermo mechanical pulping process, which had their morphological and mechanical properties compared with industrially produced Eucalyptus spp. pulp. The total yields of the pulping processes were 71.3 and 77.0% for the species Bambusa vulgaris and Dendrocalamus asper, respectively. The higher basic density presented by the biomass of the Dendrocalamus asper species can lead to a high productivity. Both bamboo species led to pulps with higher mechanical properties compared to industrial Eucalyptus spp. pulp. The pulp of Bambusa vulgaris stood out in terms of mechanical properties, reaching a higher level of mechanical properties with less energy spent on refining, being indicated for the production of papers for applications where high tensile index is required. Dendrocalamus asper pulp proved to be more suitable for applications, in which high liquid absorption capacity is required due to its high bulk.
A chemotaxonomic study on the resins of Shorea macrophylla, Shorea pinanga, and Shorea hopeifolia was conducted. The dichloromethane extracts were separated into neutral and acidic fractions and then analyzed using GC-MS. The neutral fraction analysis revealed that spathulenol, caryophyllene oxide, aromadendrene oxide, and isoaromadendrene epoxide were the major constituents in all three species. Furthermore, the main compound in the neutral fraction of Shorea hopeifolia was isocaryophyllene which was undetected in the other two species. The major constituent of the acidic fraction of the three species was hexadecanoic acid, while pentadecanoic acid was the major constituent in the acidic fraction of Shorea pinanga and Shorea hopeifolia. Therefore, the presence of sesquiterpenes as well as fatty acids in S. macrophylla, S. pinanga, and S. hopeifolia was discovered to be a marker for identifying the genus Shorea.
This article examines the current state of research on energy efficiency in the paper industry, focusing on the key strategies, technologies, and best practices for improving energy efficiency and reducing greenhouse gas emissions. The review covers a range of topics, including energy management systems, process optimisation, cogeneration, waste heat recovery, and renewable energy sources. Overall, the energy efficiency improvements can significantly reduce energy costs and carbon emissions in the paper industry. Still, there is a need for more comprehensive and integrated approaches that consider the entire value chain of paper production.
WOOD RESEARCH Volume 68, Number 4
The color of the false heartwood of Fagus sylvatica L. perceived by the human eye is in a wide range of shades from light brown-yellow to red-brown. The article analyzes the color in the color space CIE L*a*b* of dry wood of the false heartwood type: round, flame, star and marble. The color of the wood was measured with a colorimeter Color reader CR-10. The most colorful is the wood marble with a false heartwood. The results of statistical processing of the measured color values of dry beech wood, marble false heartwood on a planed surface identify it with values on the lightness coordinate L* = 65.2 ± 6.9 and on the chromatic coordinates: red color a* = 13.2 ± 2.3 and yellow b* = 19.2 ± 1.9. The most homogeneous in color is the color of the ring wood of the false heartwood with the coordinate values: L* = 63.7 ± 3.1; a* = 12.6 ± 1.7 and b* = 20.1 ± 1.6. The color diversity of the darkness and yellow-brown-red shades of the wood of the false heartwood is numerically quantified by the values of the total color difference ΔEsx* = 3.9 - 7.5. The presented values of…
The study examines how temperature and relative humidity affect the bending strength properties of hybrid eucalyptus wood from Amantia and Winneba in Ghana. Eucalyptus wood from six trees were tested based on BS 373:1957 under different temperatures and relative humidity levels. The study measured the modulus of elasticity (MOE), modulus of rupture (MOR), and moisture content (MC) of the wood samples. The results showed that MOE and MOR varied significantly across the different conditioning parameters N, T, K and G. MC also influenced the mechanical strength properties of the wood, following the wood-water relation theories. The study concluded that climate and geographical location are important factors to consider when evaluating the mechanical properties of hybrid eucalyptus. This study holds practical implications for optimizing the utilization of eucalyptus wood particularly in the construction and related industries in the three different climatic zones of Ghana
The objective of this study was to evaluate the effects of selected parameters, such as type of loading (compression and tension), the wooden dowel species, and the adhesives type on the joint stiffness. Beech, oak, and Scots pine woods were used as wooden dowel material, and polyvinylacetate (PVAc) and polyurethane (PUR) adhesives were used as adhesive agents. Elastic stiffness on diagonal tension and compression tests were applied on 120 pieces of test samples prepared. The results showed that there was found out that the highest average elastic stiffness value of 656 Nm/rad was achieved in the oak dowel joints bonded with PVAc adhesive under compression loading. The lowest average value of 293 Nm/rad was found in the Scots pine dowel joints subjected to compression stress using PUR adhesive. On average, the elastic stiffness of the oak dowel joints bonded with PVAc adhesive was 17% higher than the elastic stiffness of the Scots pine dowel joints bonded with PUR adhesive. The influence of the wooden dowel species and the adhesive type were found statistically significant
Our research focuses on identifying lignivorous fungus from decayed cedarwood. A sample was taken from Azrou forest's cedar grove, which is a part of Morocco's Ifrane National Park. On a water agar medium first, and subsequently a PDA medium, the isolated fungus was cultured and purified. After the fungus was purified, an optical microscope morphological analysis allowed us to identify the pathogen Alternaria tenuissima. These findings were confirmed by a molecular characterisation, which had a coverage rate of 94% and an identity of 94,88%. This is the first report of A. tenuissima in decomposing cedarwood that we are knowledge of.
The purpose of this research was to improve the appearance of pretreated gmelina wood (Gmelina arborea) by coloring with a natural dye. The dyes used in this research were obtained from sappan (Caesalpinia sappan) and tegeran (Cudrania javanensis) wood waste with a size of 20-40 mesh. The anatomical characteristic that determined the permeability of the gmelina wood was investigated referring to International Anatomist Wood Association (IAWA), while the characteristic of the dye was analyzed using X-ray diffraction (XRD). The wood was colored by immersing in dye mixture (ratio dye and water of 1:5 wt/wt) at room temperature during 72 h. The results showed that the lumen diameter of vessel, fiber, and pit of gmelina observed were 159 μm, 23 μm, and 6 μm, respectively. The XRD analysis showed that the structure of sappan was more amorphous than tegeran, which led to penetrate deeper into the wood. The pretreated wood provided more dyes penetration compared to the untreated wood due to the removal extractives from the wood. The pretreatment on gmelina wood would facilitate the natural dye to be impregnated into the wood cell resulting in more attractive color of the wood.
The aim of the present study was to isolate hemicelluloses by stepwise extraction with water and alkali from larch (Larix principis-rupprechtii Mayr) sapwood and heartwood. One water-soluble arabinogalactan (AG) and three alkali-soluble hemicelluloses- arabinoglucuronoxylan (AGX), galactoglucomannan (GGM) and glucomannan (GM) were obtained. The yield of AG extracted with hot-water from larch heartwood was 7.57%, it was 17.96% in total of three alkali-extracted hemicelluloses. There was no significant difference in the yield of hemicelluloses from sapwood and heartwood. Monosaccharide compositions of the hemicelluloses were determined by high performance liquid chromatography after acid hydrolysis. The results showed that galactose and mannose were the main glycosyl units of hemicellulose, followed by xylose. Galactose mainly derived from AG, whereas mannose and xylose originated from alkali-extracted hemicelluloses.
Field tests are important for evaluating how wood performs in real-world conditions and making informed choices for material selection. These tests help assess wood's durability, strength, decay processes, and resistance against harmful organisms. Furthermore, it helps users make more informed decisions about the color of wood and understand the importance of color changes depending on the place and time of use. Because weather conditions are a significant factor that influences the color of wood. Wood that is exposed to prolonged sunlight, moisture, and rain may experience fading, darkening, or staining in its color. In this study, heartwood, sapwood, and CCB impregnated sapwood samples of Scotch pine, spruce, beech and alder were exposed to the soil contact (hazard class 4) according to EN 252 for 3 years in Trabzon, Muğla, Çanakkale, and Elazığ provinces of Turkey with completely different climatic conditions from each other. Color parameters and color change values were evaluated using L*, a*, b* and ΔE* of the samples collected from test sites. The most significant color change was observed at Scotch pine in Çanakkale province. Greater color changes were observed in the heartwood of coniferous species. Impregnated samples showed the least color change.
The objective of this paper was to evaluate the effect of finger-joint reinforcement on the bending strength and stiffness of glulam beams made from high-density Eucalyptus spp. glued with resorcinol-formaldehyde adhesive. Six glulam beams were tested: three reinforced with glass fiber-reinforced polymer (GFRP) and three unreinforced for comparison. The GFRP was placed between the last two laminates and at the bottom edge of the glulam only in the finger-joint position. The stiffness and strength of glulam beams were evaluated using static bending tests, which showed that the use of GFRP reinforcement resulted in a gain of more than 100% in average ultimate bending moment and about 10% in average bending stiffness. To calculate the theoretical bending stiffness and normal stresses, a theoretical analysis of beam bending was performed using the transformed section method, which showed agreement with the experimental results.
The degradable wood-plastic composites (WPC) were prepared by compression molding in this study. Polylactic acid (PLA), poly (butylene adipate-co-terephthalate) (PBAT) and salix powder were used as the main raw materials and nano-titanium dioxide (nano-TiO2) was used as anti-ultraviolet filler. The results show that when the addition amount of nano-TIO2 was 2%, the static bending strength and elastic modulus of WPC reach 41.88 MPa and 3730 MPa, respectively, which can meet the commercial application of WPC in building formwork. At this time, the composite material has a better effect of absorbing and reflecting ultraviolet light. The static bending strength, elastic modulus, tensile strength and impact strength of WPC were reduced by 68.3%, 61.5%, 51.9% and 57.4%, respectively. The mass loss rate and water absorption were 6.1% and 22.6%, respectively, that shows its good degradation performance. This study provides a low-cost and simple method for the design of anti-UV aging, high-performance and degradable WPC, which has broad application prospects in packaging, construction and other fields.
The use of essential oils (EO) carried onto mesoporous silica particles (MSPs) was tested to control pinewood stains. Three types of MSPs were synthesized and physicochemically characterized with N2 physisorption (type IV), X-ray diffraction [Miller indices (100), (110), (200)], scanning electron microscopy, zeta potential (negative values), dynamic light scattering (< 200 nm) and thermogravimetric analysis (5% to 10% weight loss). A response surface design was used to find the EO loading conditions to control stain, the latter was measured as colour change with the CIEDE2000 formula. The essential oil loading onto MSPC was physicochemically confirmed by a weight loss of 47% in the thermogravimetric analysis. The Citrus, Syzygium sp. and Tagetes sp. oils carried onto mesoporous particles MSPC (30:1 w/w) controlled the pinewood stain caused by Alternaria sp. and Geosmithia sp. This was demonstrated by the absence of pigmentation and scarce fungal growth.
The article describes a method of preparing particleboards (PB) from fresh and recycled chips by a new technology of cold pressing after hot compression of the mat according to PCT/SK2023/000007 (ÚPV SR, 13.06.2023) using polyvinyl acetate (PVAc) glue. For comparison, the experiment was also carried out using urea formaldehyde (UF) glue and their mutual combination. The new method shortens hot pressing, or causes reduction of pressing temperatures, while the prepared PB released from pressure no longer spring and cure over time. The curing kinetics of both PVAc and UF adhesives were described by monitoring the flexural strength and modulus of elasticity of PB as a function of time after release of pressure. Modeling of the PB pressing process based on PVAc glue, which consists of overheating the pressed cross-section of the board to 90°C and its subsequent cooling to a temperature when the board is already stable, i.e. below a temperature of 70°C, was carried out using of a hot and cold press, while the pressing cycle lasted 140 s. Shortening the pressing cycle to 100 s was achieved by applying the glue to the chips already preheated to 92°C. Laboratory tests have confirmed that the mechanical properties of PB…
This study was conducted to provide information regarding to noise emission and the surface quality of silver fir wood (Abies alba Mill.) planed at different feed rates after thermal modification. Four groups of sixteen samples were prepared. One group was used as control and the others were heated at 160°C, 190°C and 220°C, at atmospheric pressure for 3 h. After, all samples were processed along the grain by a planer machine, 3 m/min and 10 m/min feed rates were applied. Noise was measured using a sound level meter, while surface roughness measurements were performed by a stylus profilometer. Higher feed rates produced noticeably higher noise emission as for natural wood as for thermally modified one. The temperature was found to have a modest positive effect on the noise reduction. The increase of temperature and feed rate affected the increase in the surface roughness of the wood. Feed rate resulted as a more significant factor on the noise emission and on the surface roughness than temperature.
In this study, transparent wood was prepared by deactivating chromophore groups in raw balsa wood, followed by solvent free dehydration and a subsequent vacuum-assisted polymer infiltration. Thermal degradation of transparent wood takes place in two main steps. Optical properties (colorimetry, transmittance) of transparent wood made from balsa wood and acrylic polymers were studied. Highest values of transmittance in the visible part of spectra were achieved by 0.7 mm thick samples at approx. 77%. The dependence of thickness on transmittance showed a linear decrease with increasing thickness of transparent wood. The created material also exhibits absorbing properties in visible and UV spectra.
The difference in density and wave velocity causes distinct wave impedance between air and wood, resulting in complex acoustic emission (AE) signals due to reflection on the wood's surface. This study explores the suppression of AE signal reflection by modifying the structure of thin wood panels, utilizing the theory of acoustic black holes (ABH). Initially, a one-dimensional ABH structure was created by forming a wedge structure on one side of the specimen. Pencil-lead break (PLB) tests simulated sudden AE sources on the specimen's surface. AE signals were collected using three equidistant sensors on the upper surface, with a sampling frequency of 2 MHz. The AE signal was then segmented into frequency bands using the differential method and analyzed in both time and frequency domains. Comparisons were made to understand the impact of the one-dimensional ABH on AE signal propagation. Results demonstrated that the one-dimensional ABH effectively suppressed AE signal reflection on the wood's surface, reducing the high-frequency components by 18.31%, 20.83%, and 12.09% for each sensor, respectively. Furthermore, the experimental cut-off frequency of 0.98 kHz surpassed the theoretically calculated value of 0.39 kHz due to the disparity between the ABH structure's thickness and the theoretical prediction.
The article is focused on the production and environmental evaluation of wood composites using waste rubber in the construction industry. Used aqueous extracts were prepared from the experimental wooden composites with various additions of the waste rubber from tires and waste seals. The pH value and organic pollution (by COD) were determined in the aqueous extracts. The effect on the environmental components (aquatic and terrestrial) was ecotoxicologically tested using the test organisms Sinapis alba, Lemna minor and Daphnia magna. Preliminary acute ecotoxicity tests were performed.
Volume 67 (2022)
WOOD RESEARCH Volume 67, Number 1
In order to improve the additional values of Salix psammophila bio-waste, pyroligneous acids (PAs) from Salix psammophila branches were extracted by the pyrolysis process at two temperature ranges: 90-380°C and 380-550°C. The chemical constituents and antimicrobial activities of PAs were investigated in detail. The GC-MS results showed that 34 compounds were identified from the two kinds of PAs. The main components were organic acids and ketones for PA at 90-380°C, while they were organic acids and phenols for PA at 380-550°C. The total content of acids and phenols was as high as 67.96% for PA at 380-550°C, which contributed to the strong antimicrobial activity. Two PAs both showed good antimicrobial activities for five pathogenic fungi and two pathogenic bacteria, especially against Verticillium dahlia. Compared with the antimicrobial activity of PA at 90-380°C, PA at 380-550°C showed greater antifungal activity but against Fusarium oxysporum.
In this work, the compression behaviour of the Xinjiang poplar column was reinforced by basalt fibre reinforced polymer (BFRP) strips with different reinforced configurations, and the numerical simulations were performed on the axial and eccentric compressions of poplar columns unreinforced and reinforced with BFRP to assess the effect of the bearing capacity and deformation of the columns. The results show that the use of BFRP to reinforce the Xinjiang poplar column effectively improves its axial compressive bearing capacity (axial compression) and bending bearing capacity (eccentric compression), and at the same time, the bearing capacity and stiffness of the columns strengthened by BFRP increased with the bonding area of BFRP.
The methods of coated paperboards smoothing with a hot stamping machine using a smooth metal die and a conventional calender were compared. The printing roughness required for printing electrical and electronic components was achieved by both smoothing methods. The printing roughness of the coated paperboards decreased after hot stamping by 18 to 42% and after calendering by 22 to 41% depending on the grade of coated paperboard. The stiffness of coated paperboards decreased after hot stamping by only 4 to 21%, while by up to 38 to 51% after calendering. The ratio of specific stiffness and printing roughness of coated paperboards after hot stamping ranged from 2.5 to 8.1 mN. μm-2 and after calendering from 2.0 to 6.7 mN. μm-2. The stiffness of the coated paperboards decreased less after hot stamping, and that only in the printed electronics area, while after calendering the stiffness decreased significantly more in the whole profile. It can be assumed that packaging made from coated paperboards smoothed by hot stamping will have a lower weight and thus lower costs than packaging from calendered coated paperboards.
A few variations of open-holes in wood-based pieces, particle board and plywood were modeled in this article. The modulus of elasticity and the coefficient of damping for these pieces were determined using static and dynamic methods and the effect of holes of different quantity and size on mechanical properties were evaluated. As regards to wood particle boards, it was found that the modulus of elasticity decreased to10% after drilling holes, and the coefficient of damping increased to 13%. With regard to plywood pieces these changes were up to 14.5% and up to 21.5%, respectively.
Eucalyptus urophylla was treated with melamine-urea-formaldehyde resin (MUF) after pretreatment with urea solution. The properties of the wood were then determined. The weight percent gain (WPG) and, antiswelling efficiencies (ASE) of the wood treated with urea+MUF were 14% and, 45% higher than those of untreated wood, respectively. The water absorption (WA) of the wood treated with urea+MUF was decreased approximately 50% lower than that of the untreated wood. However, the mechanical properties of the wood treated with urea+MUF were weakened due to the destruction of the structure of wood. An X-ray photoelectron spectroscopy (XPS) analysis revealed that the atomic concentration ratio of O/C was increased. The ratio of C1 was decreased as the lignin and extractives contents were decreased, while the ratios of C2 and C3 were increased. The urea solution pretreatment was conducive to the impregnation of wood functional modifiers.
Our paper proposed a new type of environmentally friendly biomass material, corn straw integrated material (CSIM). In this paper, the ultimate bearing capacity of the axially compressed components under parallel, vertical and combined texture-integrated methods are compared and analyzed through the experimental research. The influence of size effect on the bearing capacity of the axially compressed components of the CSIM is determined, and the calculation method of the bearing capacity of the axially compressed components under vertical texture-integrated method is proposed. Results showed that the slenderness ratio of 35 was the dividing point between the strength and instability failures of the CSIM axially compressed component, and the calculated value of the revised bearing capacity calculation method agreed with the test value. The result is very close to the American National design specification for wood construction (ANSI/AF&PA NDS, 2005).
To utilize wood resources in Mongolia, amounts of wood chemical components (hot-water extracts, 1% NaOH extracts, ethanol-toluene extracts, holocellulose, -, -, and -cellulose, Klason lignin, and ash) were determined in four common Mongolian softwoods, Pinus sylvestris, Pinus sibirica, Picea obovata, and Larix sibirica. In addition, decay resistance of heartwood was evaluated against a white-rot fungus Trametes versicolor, and a brown-rot fungus Formitopsis palustris. Among the four species, heartwood of Larix sibirica was chemically characterized by higher amounts of hot-water and 1% NaOH extracts, and lower amounts of holocellulose and Klason lignin. These characteristics may be related to the presence of arabinogalactan which is easily extracted with cold water. Mean mass loss in each softwood ranged from 6.9% to 28.1% in white-rot fungus, and from 24.8% to 48.3% in brown-rot fungus. Among four species, Pinus sibirica showed the highest decay resistance against both fungi. By the linear mixed-effects model analysis, negative relationships were found between mass loss and amounts of extracts in heartwood, suggesting that heartwood having larger amounts of extracts showed higher natural decay durability.
The chemical constituents of ethyl acetate extracts from heartwood and sapwood of different ages of Dalbergia sissoo were studied by gas chromatography-mass spectrometry. The results showed that the chemical composition of wood heartwood and sapwood is significantly different. In the vertical direction, the type of the ethyl acetate extract from Dalbergia sissoo tends to decrease from the base to the upper portion; in the horizontal direction, the type of extract gradually decreases from the center to the periphery. And it showed an increasing trend with the age of the trees. The experiment also revealed that there were significant differences in chemical components between heartwood and sapwood. We speculated that the main chemical component trismethoxyresveratrol of heartwood extract may be related to the formation of heartwood, and the specific correlation needs to be further verified.
Teak wood is used at the juvenile stage due to short-rotation, therefore, this study aims to describe the extractive content of stem, bark, branch, and twig parts of the wood as value-added chemicals from secondary metabolites. Moreover, the main stems comprise of sapwood, heartwood, and bark while the branch and twig are made of sapwood together with bark. In this study, the sample trees were 6 and 8 years old with three replications from clonal superior teak wood and were extracted using n-hexane, methanol, and hot water as the solvents. The average of n-hexane, methanol, hot water, and total extractives ranged from 0.49 to 2.77%, 2.27 to 17.76%, 0.65 to 7.47%, and 5.96 to 25.40%, respectively. Furthermore, the total phenolic content from soluble n-hexane and methanol extracts ranged from 162.16 to 295.24 mg GAE/g, while the total soluble polysaccharides ranged from 166.28 to 423.97 mg GluE/g. The results showed that the 8-year-samples had higher values in methanol extractive content (MEC) and lower in hot-water extractive content (HWEC) than the 6-year-old trees. In addition, the bark together with sapwood in branch and twig parts had higher concentrations of MEC and total extractive content (TEC) compared to the main stems. For radial…
In this paper, computer vision technology is used to quickly and accurately identify and classify the surface defects of processed bamboo, which overcomes the low efficiency of manual identification. The datasets consist of 6360 defective bamboo mat images of four categories taken by the author at the same position, which are split at a ratio of 8:2 for training and testing. In this experiment, we improved the U-net to segment the datasets and use VGG16, GoogLeNet and ResNet50 with attention mechanism for classification and comparison. The experimental results show that the accuracy of this method is 5.65% higher than the commonly used neural network method. The highest accuracy rate is 99.2%.
The main purpose of this study was to develop new methods to eliminate the problems encountered during the impregnation of wood material, and in this context, to improve the retention of wood material by using liquefied nitrogen. Uludağ Fir (Abies nordmanniana subsp. Bornmulleriana) was used as wood material impregnated with Tanalith-E, Immersol aqua and borax. The effects of liquid nitrogen and the amount of retention on the mechanical properties were investigated. Application of liquid nitrogen before impregnation has increased the retention in fir wood by an average of 150-200% in all impregnation methods, compared to the groups without liquid nitrogen application. Despite this increase in retention amounts, no significant changes were observed in mechanical properties due to the application of liquid nitrogen.
Six species of wood (Vachellia nilotica, Eucalyptus camaldulensis, Ziziphus mauritiana, Albizia lebbeck, Melia azedarach, Dalbergia sissoo) were tested in compression and tension parallel to the grain. The specimens were collected from different areas of Pakistan. The compressive strengths, tension parallel to grain and hardness of the wood were determined by testing rectangular shape wooden specimens (ASTM D143 2014, Janka 1906). It was observed that compressive and tensile strength of Vachllia nilotica parallel to the grain is higher than other species whereas, Eucalyptus camaldulensis hardness behaviour along radial and tangential surface is higher among the wooden samples tested.
Whereas the traditional manual detection method of wood defects is problematic due time-consuming, low efficiency and low accuracy, an derived model based on ResNet-v2 was constructed. The new derived model can accurately point out the types of defects such as wormhole, live joint and dead joint on the surface of plate, improve the accuracy of classification, and greatly reduce the labor force. Compared with the traditional convolutional neural network, ResNet-v2 derived model has better recognition effect and stronger generalization ability. The experimental results show that the classification accuracy of ResNet-v2 derived network model based on different number of layers is more than 80%, and the classification accuracy of ResNet-v2 derived model can reach 97.27%.
The relaxation of growth stress in trees growing in fast-growth conditions, as plantation in tropical areas, affects lumber quality during of sawing or drying process. It was evaluated two pretreatments (heating and steaming application) before sawing process and endless screw use to maintain the boards pressed during drying of Dipteryx panamensis and Hieronyma alchorneoides wood with objective to reduce the effects of relaxation of growth stress. The results showed endless screw is used to maintain the boards pressed, the moisture content (MC) or drying rate did not vary. The use of endless screws with daily adjustment during drying produced a reduction of cup, check and split defects in lumber and this treatment is ccompanied with a pre-treatment before sawing (heating or steaming treatment) decreased the incidence of drying defects. Then the use of both treatments is an opportunity to reduce the effects of relaxation of growth stress on the quality of the wood of D. panamensis and H. alchorneoides from fast-growth plantation conditions.
In this paper, an experimental investigation on the low-velocity impact response of wood-based bio-composites is presented. This study is to map the suitability of plant-based materials instead of petroleum-based plastic as a constituent raw material in composites. Wood-based composites panels were made from southern yellow pine (SYP), corn starch (CS), and methylene diphenyl diisocyanate (MDI) using a Diefenbacher hot press. The impact performance of the specimens was evaluated in terms of energy absorption capacity. Five types of bio-composites were prepared with varying compositions with SYP: 4% MDI; 2% CS and 2% MDI; 2% CS and 4% MDI; 4% CS and 4% MDI. These samples were prepared at two different manufacturing pressures. The bio-composite produced with higher manufacturing pressure had the highest absorbed energy among five different types of bio-composites, this shows that material behavior at impact loading is strongly dependent on the manufacturing pressure during fabrication.
WOOD RESEARCH Volume 67, Number 2
The article deals with the effects of bulk density on thermal conductivity in specimens of 15 Korean woods (Zelkova serrata, Pinus densiflora, Cornus controversa, Betula schmidtii, Betula platyphylla var. japonica, Ginkgo biloba L., Cedrela sinensis A. Juss., Fraxinus mandshurica, Ulmus davidiana var. japonica, Prunus sargentii Rehder, Paulownia tomentosa (Thunb.) Steud., Larix kaempferi (Lamb.) Carrière, Robinia pseudoacacia, Kalopanax septemlobus and Tilia amurensis). The results of this study were compared with previous studies performed on wood specimens from China, India, and Turkey. Consistent with these previous studies, bulk density and thermal conductivity were positively correlated in Korean woods, and a simple regression model with a very high correlation of R2 (94%) was obtained. Interestingly, we observed some variation between our simple regression models and those generated by previous researchers who had examined non-Korean woods.
This study describes the seasonal dynamic changes of heartwood transformation of Larix gmelinii by establishing the relationship between trunk radius, heartwood radius, sapwood width, trunk growth rings and heartwood growth rings in different heights during the growth season with regression analysis. The results showed that the initial age of heartwood formation was 7.25 years. Heartwood began to form when the trunk radius was greater than 2.6 cm, and then the heartwood radius grew 0.85 cm for every 1.00 cm growth of the trunk radius. It was also demonstrated that the significant change and growth rate of heartwood with month were higher than sapwood at the tree base and 1 m height, but lower than sapwood at 5 m and 9 m height. The absolute content of heartwood and sapwood area decreased with tree height, however, the relative content of sapwood area increased with the tree height.
This study initially investigated decay resistance of preservative injected poplar and its infection mechanism of preventing white rot fungi. The living poplar was injected with different concentrations (0.0, 0.5, 1.0 and 1.5 wt.%) of alkaline copper quaternary (ACQ). Using the scanning electron microscopy, the process of preservative injected poplar wood preventing white rot fungi infection at different tree heights were examined. The decay resistance test results showed that the decay resistance of preservative injected poplar at different tree heights was significantly different. With the increase in tree height, the decay resistance decreased, and the higher the ACQ concentration, the better the decay resistance. The white rot fungi infested the poplar wood with the vessels as the breakthrough point, being spread to other cells through pits. The white rot fungi degraded wood cell walls by secreting enzymes and preferentially degraded the parenchyma cells.
This study compared steeping Leucaena leucocephala wood with boron compounds and acetic acid to protect it from termites (Coptotermes gestroi). The experiment had a completely randomized design with 10 treatments involving three wood preservatives (acetic acid, boron compounds, and mixtures of both), three treatment lengths (1, 12, and 24 h), and untreated wood, with five replicates of each for a total of 50 conditions. The moisture content of the wood and the wood destroyed by termites were assessed. The L. leucocephala wood treated with boron compounds for 1 h resulted increase in moisture content and no termite damage.
In this study, eight types of boron-based flame retardants were performed to evaluate the effects of different boron components on the combustibility of the bamboo filaments. Disodium octaborate tetrahydrate, boric acid/borax, and nano-ZnBO4 were used as the active flame retardant components. Besides, other inorganic flame retardants including nano-SiO2 and ammonium polyphosphate (APP) were also introduced in order to increase the flame retardant of these boron-based components. The combustibility of the bamboo filaments treated with different flame retardants were evaluated by cone calorimeter analysis. The results showed that the flame retardants including the heat release and smoke release resistance of the bamboo filaments with different boron-based components and nano-SiO2 or APP, could be significantly improved, especially, in the samples treated with the compound flame retardant composed of boric acid, borax and nano-SiO2, which was attributed to the synergistic effect of these flame retardant components.
In order to analyze the influence of moisture content variation on Cedrella odorata wood specie on strength and stiffness properties, considering 12% moisture content up to fiber saturation point (FSP). Most of strength and stiffness properties analyzed were significantly influenced by moisture content according statistical analysis. ANOVA, Anderson Darling and Multiple comparison tests were used at 5% significance level. Considering that most of properties were affected by moisture content, the equations to estimate wood properties according moisture decrease are quite precise, but most of estimations were higher than experimental values at 12% moisture content, indicating the need of a standard review for such estimators, which may lead to an unsafe timber structure design.
The conducted study was aimed at finding the phenol-formaldehyde adhesive formulation containing both the nanoclay and the tannin filler which allows to manufacture water-resistant plywood characterized by the improved properties. The research assumed the application of six experimental variants having a different proportions of the mentioned components which were compared with the mixture prepared according to the industrial recipe. Properties of liquid mixtures such as their gelation time and viscosity were investigated. Moreover, the differential scanning calorimetry (DSC) was performed. The manufactured plywood panels were tested in terms of bonding quality, bending strength and modulus of elasticity. Studies have shown that after the adjustment in components proportions it is possible to achieve the proper viscosity level of adhesive mixtures. The results also indicated that the suitable amount of nanoclay can contribute to the acceleration of resin gel time, however, the DSC analysis showed no effect on its reactivity. The nanoclay concentrations ranging from 2 to 4 pbw (parts by weight) per 100 g of adhesive positively influenced the bonding quality of plywood. Furthermore, there was no clear tendency in case of the effect of applied formulation on the modulus of elasticity and bending strength of plywood. The mixture containing 3…
This paper models bench-scale experiments using computational fluid dynamics (CFD). The experiments measured the temperature profiles of fire-protected cross laminated timber (CLT) specimens exposed to parametric fire curve. The bench-scale experiment specimen is 250 x 250 mm and consists of a CLT panel 100 mm with three layers of gypsum plasterboard 15.5 mm as thermal and fire insulation The specimens were exposed to a heat flux generated by a heat-transfer rate inducing system (H-TRIS) device. Two numerical models were created in order to copy the experiment conditions, one by using basic modelling techniques and one using advanced method. Comparing the layer temperature values of the experiment and basic model, a great difference was found. The difference between experimental and model temperatures increases the closer the analysed layer is to the heat source. The results show a good agreement between the model and the experiments, especially for the advanced numerical model.
After flame retardant and enhancing treatment, fast-grown poplar face the problem of leaching of pharmacy, which affected the effective permanence of the retard and further use is limited. In this paper, we study the fixed effect of low molecule phenol-formaldehyde (PF) resin on nitrogen and phosphorus (N-P) inorganic flame retardant composite under the condition of high relative humidity. The change of lateral sizes and quality of the specimens were emphasized in the experiment. Results reveal that the greater the concentration of flame retardant was, the greater weight gain percentage of the samples was, and the more serious leach was in the test, after the specimen was modified with the flame retardant. When weight gain percentage of the specimens is same, the greater the concentration of PF resin test solution was, better effect of the leach resistant will be obtained with the concentration of PF test solution increased. The PF resin with 25% concentration had the best effect to reduce the leach of N-P inorganic composite retards. From the comparative analysis above, it was advisable to indicate the PF resin with 25% concentration had the best effect to reduce the leach of N-P inorganic composite retards.
The fracture behavior of southern yellow pine (Pinus taeda L.) was experimentally analyzed in the radial-longitudinal and the radial-tangential crack propagation systems using a single-edge-notched bending test method in mode I loading condition. Three fracture parameters, the initial slope, the fracture toughness, and the specific fracture energy, were determined from the obtained load-deformation curves of each test sample. The results were statistically analyzed and compared with each other using the independent samples t-test. The radial-longitudinal crack propagation system had a significantly greater fracture toughness than in the radial-tangential crack propagation system. The stiffness in the radial-longitudinal system was also significantly higher than in the radial-tangential system. It was observed that the crack growing in the tangential direction needed more energy per unit area to separate a wood sample into two halves. However, there was no significant difference between the specific fracture energy values of crack propagation systems.
As the preferable lateral resistance system of a wood shear wall is attributed to the good lateral performance of nail connection, this paper aims at investigating the pull-out and shear performances of framing members’ nail connection in wood shear walls under monotonic loading. It was found that the main failure mode of the pull-out behavior of nail connection was the withdrawal of threaded nails from framing members. In addition, the shear behavior of nail connection was characterized by plastic hinge of threaded nails, local tear of spruce-pine-fir (SPF) on the top of nails, and nail caps that were obliquely embedded into the surface of SPF. The average ultimate load and displacement of shear mode were 1.48 times and 5.12 times higher than those of pull-out mode, respectively. According to the research results, the corresponding exponential numerical model was established, which provided basic data for the lateral performance research and finite element simulation analysis of wood shear walls nail connection.
This study focused on the effect of wood flour content on some mechanical and physical properties of flat pressed wood plastic composites (WPC). The results revealed changes in the wood flour content affected the density of flat pressed WPC. Moreover, as exposure time increased, water absorption values were increased. The changes in the wood flour content considerably affected the mechanical properties of WPC. The decrease in the flexural strength reached up to 58%, while it was 61% for tensile strength. However, modulus of elasticity increased with increasing wood flour content. Meanwhile, the decrease was inevitable for screw withdrawal strength, where the increase in wood flour content resulted in a reduction of up to 50%. It was clearly determined that wood flour content above 60% evidently affects the physical and mechanical properties of flat pressed WPC, which should be considered in the utilization areas where high mechanical properties are critical.
By adopting the methods of PAD subjective emotion measurement and galvanic skin response physiological measurement, this study explores the differences in people's tactile perception evaluation of the surfaces of beech materials with different roughness and shapes. The results show that females prefer beech samples with arc shapes, while males prefer the samples with rectangle shapes; participants' emotional stability under a higher emotional arousal level can to a certain extent be maintained due to the beech materials with arc shapes. The tactile perception of males for beech materials has a greater range of emotional arousal than that of females, but the arousal speed of males' emotions is lower than that of females' emotions. Moreover, a better tactile perception experience can be created for participants when the roughness of beech materials is limited within a certain range of conditions, and a certain sense of "anxiousness" will be brought to participants if the surface of beech materials is too rough.
The purpose of this study is to investigate the contact temperature and thermal comfort when the upper extremity touches a wooden table top, and to seek an efficient accurate simulation device instead of human testing. Therefore, three parts of this paper were conducted. First, 20 subjects were selected for the temperature test experiment. Secondly, the perceptual thermal comfort evaluation was quantified by recording the thermal comfort evaluation at a specific moment. Finally, a device was developed to replace the human forearm for upper limb thermal comfort study. The results show that the ambient temperature, type and thickness of material all have significant effects on the local contact temperature. In terms of thermal comfort evaluation, the correlation between temperature and thermal comfort was significant. The simulation device in the study is not only simple to operate, but also can continuously and stably replace the heat transfer process of the upper limb.
Nanofibrillated cellulose was prepared from distillery refuse based on maize starch using the extraction with NaOH and HCl involving centrifugation. SEM images of bleached kraft pulp with/without the addition of nanofibrillated cellulose were compared. The results showed that the application of nanofibrillated cellulose caused a visible reduction in the surface porosity. Conversely, mixing of the pulp with the nanofibrillated cellulose resulted in large pores among the fibres. The effect of the cationic retention aid on porosity was not significant, observed in the fines retention. A minimal difference in porosity was found among of fine and coarse fibres. When lyophilisation as drying method was used it yielded nanofibrillated cellulose with a size in the range of approximately 100 to 150 nm.
WOOD RESEARCH Volume 67, Number 3
The study analyzed the impact of heat treatment conditions (temperature and duration) on the surface color and glossiness of young eucalyptus wood. The young eucalyptus wood samples were treated at different treatment temperatures (165°C, 185°C, 205°C) and duration (2 h, 3 h, 4 h). The color of the young eucalyptus wood was determined using CIE L*a*b* system and the gloss was measured with glossmeter at 20°, 60°, and 85° incident angle before and after the heat treatment. The total color difference (E* ), lightness (L*), red-green index (a*), and yellow-blue index (b*), were investigated at different treatment conditions. The values of L* and b* decrease continuously with the increasing temperature and duration. The results of analysis of variance (two-way ANOVA) indicate that the heat treatment temperature has a significant effect on the colorimetric properties of the heat-treated young eucalyptus wood. The gloss decreased after the heat treatment for both perpendicular and parallel directions. ANOVA analysis showed that the treatment temperature duration have a significant effect on the parallel glossiness of 85°(p＜0.05). These are probably due to differences in surface roughness between untreated and heat-treated wood. To achieve the desired color like teak wood, the preferred temperature is no more than…
The wood of the beech (Fagus Sylvatica L.) was steamed with a saturated steam-air mixture at a temperature of t = 95°C, or saturated steam at t = 115°C and t = 135°C to obtain a pale pink, red-brown and rich brown-red color. Subsequently, samples of unsteamed and steamed beech wood were irradiated with a UV lamp in a Xenotest Q-SUN Xe-3-HS after drying in order to test the color stability of steamed beech wood. The color change of the wood surface was evaluated by means of measured values on the coordinates of the color space CIE L*a*b*. The results show that the surface of unsteamed beech wood as well as steamed beech wood with a steam-air mixture at a temperature of t = 95°C and saturated steam with a temperature of t = 125°C darkened and turned brown to a brown-yellow color due to UV radiation. The deep brown-red color of the surface of beech wood steamed with saturated steam with a temperature of t = 135°C brightened to a brown-yellow color similar to the color of unsteamed beech wood. The analysis of the changes in the color space CIE L* a* b* shows that the greater the darkening…
In this study, we investigated why the sound-absorbing performance is different with between heartwood and sapwood of yellow poplar, which are known for their sound-absorbing properties. We performed image observation as well as gas permeability, pore size, and porosity analysis, and measured the sound absorption coefficient of all samples using an impedance tube. We determined that the pores were significantly larger, and the gas permeability and through-pore porosity much higher, in the sapwood than the heartwood. The average sound absorption coefficient of the sapwood at 2000-6400 Hz (0.61 ± 0.04) was 2.7x that of the heartwood (0.23 ± 0.03). The average NRC of the sapwood (0.23 ± 0.01) was 1.9x that of the heartwood (0.12 ± 0.01). This study ultimately determined that the sapwood, as a consequence of its larger pore size and superior through-pore porosity, which thereby improved its gas permeability, outperformed the heartwood in terms of sound-absorption. We also determined that pore size and through-pore porosity were the primary parameters that determined the sound-absorbing performance of yellow poplar cross-sections.
Characteristics of hawthorn wood concerning soil physicochemical properties were studied. Physical properties such as dry wood density and volumetric swelling and fiber dimension parameters like fiber length, fiber diameter, and cell wall thickness were investigated. Soil properties including clay, silt soil, sand soil, electrical conductivity, pH, nitrogen, phosphorus, potassium, and organic matter content were determined. Pearson correlation was applied to explore the relationship between soil and wood properties. The mean wood density and volumetric swelling obtained were 0.71 g.cm-3 and 18%, respectively. Moreover, the mean values of fiber length, fiber diameter, and cell wall thickness were 0.80 mm, 20.50 μm, and 5.78 μm, respectively. Pearson correlation analysis showed a significant and positive correlation between wood dry density, cell wall thickness and volumetric swelling with percentage of silt, while a negative relationship between fiber length and percentage of silt were found.
In this study, low-density plantation timber, Paraserianthes falcataria was pretreated with 3%, 6% and 9% NaOH before densification process. Alkaline pretreatment leads to lignin reductions and cell wall structure becomes more porous. Densification was done by crushing the cell wall with hot-press machine, resulting in reduction of thickness to about 60%. Scanning electron microscopy images were captured and processed through ImageJ software. As to support the data, lignin content determination was conducted according to TAPPI T222 and the correlation coefficient between cell lumen areas and lignin content were studied statistically.
One of the limited information about the acoustic characteristics of wood is the timbre harmony. We measure the sound harmony of selected hardwood species using a timbre harmonic model. 324 wood samples of 20 x 20 x 300 mm (R x T x L) were collected axially from 12 trees of Albizia adianthifolia, Gmelina arborea, Delonix regia and Boscia anguistifolia for the experiment. Results were subjected to descriptive statistics and analysis of variance. The timbre harmonic model prescribed a scale of 0-1, 0 being the perfect harmonic while 1 represents imperfect harmonic. G. arborea wood had the significantly lowest mean timbre harmonic of 0.078 ± 0.006, thus it had the best sound harmony. Meanwhile, A. adianthifolia wood had the highest timbre harmonic value (0.120 ± 0.008). Conclusively, this study successfully measured the timbre harmonic of sound from selected hardwood species and information provided revealed the species all performed fairly, owing to their values closer to 0.00.
Pinus massoniana Lamb. wood particleboards processed by inorganic and organic fire retardants of two densities were prepared by isocyanate and MUF resin. Variations of internal bonding strength (IB), modulus of rupture (MOR), modulus of elasticity (MOE) and thickness swelling rate (TS) of particleboard were observed. Results demonstrated decreasing of IB from 0.81 MPa to 0.42 MPa and 0.36 MPa, MOR from 17.3 MPa to 12.5 MPa and 12.3 MPa, MOE from 1840 MPa to 1328 MPa and 1117 MPa, and increasing of TS from 5.2% to 15.1% and 11.2%, respectively, for the treated MUF particleboards of density 0.65 g.cm-3. Similarly, decreasing of IB from 0.93 MPa to 0.66 MPa and 0.64 MPa, MOR from 16.2 MPa to 10.6 MPa and 12.1 MPa, MOE from 1246 MPa to 1573 MPa and 1466 MPa, and increasing of TS from 6.7% to 7.1% and 6.0%, respectively, when isocyanate adhesive was used. The similar changes were showed when the density of particleboard was 0.75 g.cm-3. Improving density of particleboard appropriately and decrease density difference between the surface to chip layers could make the profile density curve tend to be stable, which could get a relatively high mechanical strength and water resistance. Synergistic effects between…
The paper presents an investigation on a timber joint with an inserted steel plate under fire exposure. According to standard EN 1995-1-2 (2004), the fire resistance of unprotected timber joints is limited to 30 min. However, several studies have shown that these joints can achieve higher fire resistance comparing to values given in the standard. In order to verify this, a numerical model of bolted steel-timber joint at elevated temperature was created. The presented model is focused on heat transport in the joint, which is affected by the presence of the steel plate and bolts. The model was validated on experimental results taken from literature and on measurement from a fire tests conducted in a medium-sized furnace. Considering the results of validation, the model has a good ability to predict residual cross-section, temperature of steel plate and bolts and temperature of timber elements. The results of validated numerical model are also compared to the analytical model.
In this paper, wood-wool panel was prepared by steam pressing as opposed to the traditional cold-pressing and hot-pressing methods in order to eliminate the shortcomings of both methods. Cold pressed wood panels have low strength. The overall performance of heat pressed wood panel was poor. The water absorption of these two panels was too large. The steam pressing mechanism was studied by the means of X-ray diffraction and scanning electron microscope. The surface structure, moisture absorption and mechanical properties of wood-wool panel were investigated by experimental testing and numerical analysis. The surface structure of the wood-wool panel became stable, the moisture absorption was reduced, and the mechanical properties of the wood-wool panel were enhanced. The static bending strength of autoclaved wood-wool panel was 4% higher than that of cold-pressed wood-wool panel, and 7.4% higher than that of hot-pressed wood-wool panel. And the sound absorption coefficient increased by 6.3% and 5% respectively. The thermal conductivity was 2.4% lower than that of cold-pressed wood-wool panel.
A roll tensioning process for circular saw blades with four typical body structures was built with the finite element method. After roll tensioning, the elastoplastic deformation behaviors of the four blades were simulated and tested and the effects of roll reduction displacement on flatness were analyzed. The abilities of the blades to withstand cutting temperature load after the roll tensioning process were compared. The theoretical results showed that each of the four circular saw blades with unique body structures had different process parameters in an appropriate tensioning state. Circular saw blades with different body structures showed variation in improvements of their ability to withstand cutting temperature load after an appropriate tensioning process.
Latest scientific findings and policy guidelines emphasize the importance of returning bio-based waste raw materials through cascading use, also including post-consumer wood (PCW). To accomplish the concept of cascading use it is crucial to properly sort PCW given by the quality of raw materials which is resource consuming process. For this purpose, we have (1) selected appropriate activities, (2) constructed a model with different sub models in time, fuel and energy consumption, and (3) defined the inputs, performed calculations and presented (mid) outputs. In the case study all sub models have been compared with each other, demonstrated on the example of Slovenia. The results show that the reuse of wood is justified and should be implemented to a greater extent. Sensitivity analysis has exposed that modifying the values of the input parameters or (mid) outputs may change the final results in time and fuel consumption among selected sub models.
Inspired by the successful application of deep convolutional neural network, a coniferous micro-graphs retrieval framework based on deep learning and image processing technology is proposed. The idea of the proposed framework is that the texture feature of representing three section surfaces can be learned and classified by a fully CNN, and the canals can be deep learned by an U-net CNN when the data labels are available. In addition, the image processing technologies are also proposed to identify whether the growth ring boundaries are distinct and whether there is a “window-like” cross-field pitting. Finally, a coniferous micro-graphs retrieval system is realized based the proposed methods. Experimental results demonstrate that this system outperforms in terms of recognition accuracy. In addition, the system can be further developed into more intelligent coniferous retrieval system that can automatically identify more coniferous microscopic features, so as to obtain more accurate retrieval results.
Deep learning-based methods, especially convolutional neural networks (CNNs), have shown their effectiveness for image classification. In this paper, vision transformer technology is used to classify the surface defects of processed bamboo, which can be more quick and accurate compared with the low efficiency of manual identification. In the first step, we replace the activation function from Gelu to Mish in the encoder part, but the classification performance is not satisfied. Then, to get a better classification results, we keep the original activation function and introduce the DropBlock. Compared with dropout, DropBlock can obtain better classification accuracy. Finally, compared with the results after transfer learning, it is proved that replacing dropout with DropBlock can improve the classification accuracy. The results on the bamboo chip datasets show that the accuracy of this method is 2% higher than the original transformer network whether using transfer learning.
The basic properties of calcium sulfate whiskers were studied and compared with commercial ground calcium carbonate (GCC) fillers. The modified whiskers were used for paper filling and compared with a commercial precipitated calcium carbonate (PCC). As a result, it shows that when the unmodified calcium sulfate whisker is used to fill the paper, the ash content of the handmade sheet is low because of its dissolution problem. The ash content of the paper increased obviously when the modified calcium sulfate whisker was added, which reached the ash level of PCC filling. In addition, the paper strength increased greatly, but the light scattering coefficient decreased. In addition, the strength property of the modified calcium sulfate whisker filling paper is basically the same as that of the PCC filling paper with 14.99% ash content when the ash content of the modified calcium sulfate whisker filling paper is 21.95%.
WOOD RESEARCH Volume 67, Number 4
This study aims to provide information on Betula pendula cell wall synthesis genes regarding their potential physiological roles and the molecular mechanism associated. Here we identified 46 gene models in 7 gene families that encode cellulose synthase and related enzymes of B. pendula, and the transcript abundance of these genes in xylem, root, leaf, and flower tissues also be determined. Based on these RNA-seq data, we have identified 8 genes that most likely participate in cell wall synthesis, which include 3 cellulose synthase genes and 5 cellulose synthase-like genes. In parallel, a gene co-expression network was also constructed based on transcriptome sequencing. These analyses will help decipher the genetic information of B. pendula cell wall synthesis genes and alter its wood structure on the cellular level.
The paper deals with anatomical characteristics of wood fibres of Quercus robur L. Fiber length, double-cell wall thickness and fiber lumen diameter were analysed from samples in flooded and non-flooded area along Sava river in Serbia. All anatomical elements were measured from pith to bark in order to establish variation with cambial age, not only between researched sites, but also between individuals within each locality. In this study, there was no statistically significant difference only for mean values of fiber length between individual trees at non-flooded area, and in fiber lumen diameter at flooded area. Increasing of mean values of observed anatomical parameters with cambial age is valid for flooded area (MU „Grabovako-vitojevačko ostrvo 20e“), while for another locality (MU “Blata-Malovanci”) it is the case just for double-cell wall thickness. Mean values of all analysed anatomical elements are bigger in flooded area and this could be a consequence of more suitable ecological conditions for Quercus robur L. development present in this locality. Obtained variations show nonhomogeneous wood fibre features at both localities.
In order to classify the decay levels of Chinese fir (Cunninghamia lanceolata) wood components in arcade buildings in the ancient town Chikan and to provide basic data for future protection measures, the extent of decay of the samples was determined via polarized light, fluorescence, and Fourier-transform infrared spectroscopy. The results were as follows: (1) The total birefringence brightness of crystalline cellulose and the green fluorescence brightness of the lignins were reduced to different degrees in almost all samples. (2) The absorption peaks at 1731 cm-1 representing hemicellulose and at 891 cm-1 representing cellulose in all samples disappeared. The absorption peak heights at 1370 cm-1, 1159 cm-1 and 1058 cm-1 which represents holocellulose, and at 1508 cm-1, 1424 cm-1, and 1262 cm-1 which represents lignin decreased to varying degrees. (3) From the analysis, the decay level of wooden components in arcade buildings was divided into three classes, i.e., Level I (severe decay), Level II (moderate decay), and Level III (mild decay).
This study focused on Duabanga moluccana, which is a fast-growing tropical tree native to Southeast Asia. Duabanga moluccana cross sectional specimens were analyzed to gas permeability, pore size, and open-pore porosity and also measured its sound absorption coefficients with an impedance tube. Duabanga moluccana showed a larger pore size and greater open-pore porosity than other hardwood species, and its sound absorbing performance was superior to that of the gypsum board currently used as a commercial ceiling material. Although this was a laboratory-scale investigation, we demonstrate that Duabanga moluccana cross sections have potential as a natural sound absorbing functional building material.
This study was aimed at producing single-cell (SCP) protein from the carbohydrate hydrolysate of steam-exploded eucalyptus (Eucalyptus urophylla) wood. Two yeast strains including Saccharomyces cerevisiae and Candida utilis 2.587 were used for batch fermentation. Results showed that the total reducing sugars (TRS), glucose and xylose in hydrolysate had concentrations of 17.52, 10.71, and 4.30 g•L-1, respectively. During fermentation, yeast strains of S. cerevisiae and C. utilis 2.587 used monosaccharides sequentially, and secondary growth occurred. The yeast biomass contained 43.59% crude protein and was rich in all essential amino acids such as lysine, leucine, and valine. Total amino acid reached 401.45 g•kg-1, and corresponded with the standard recommended by the Food and Agriculture Organization of the United Nations for amino acids, except sulfur-containing amino acids.
To study the propagation law of acoustic emission (AE) longitudinal waves in wood, the relationship among wave velocity, standing wave fundamental frequency and Young's modulus of elasticity was studied, and the energy decay model of AE longitudinal waves along the grain direction was established. Firstly, the propagation velocity of the longitudinal wave was calculated using the time-difference method. Then, the relationship between the wave velocity and Young's modulus of elasticity was analyzed and the method of calculating the longitudinal wave velocity using the fundamental frequency was proposed. Finally, using different levels' pulse strings as AE sources, the attenuation law of AE signal energy with distance was studied. The results show that the longitudinal wave velocity can be estimated more accurately by using the standing wave fundamental frequency. The influence of Poisson's ratio needs to be considered when calculating the Young's modulus of elasticity by using the longitudinal wave velocity.
The aim of this research was study of polyurethane (PUR), isocyanate polymer emulsions (EPI) and melamine-urea-formaldehyde (MUF) adhesives, on the bonding properties of solid and hollow glulam beams of Pinus radiata. The thermomechanical analysis (DMA) of the adhesives was carried out to evaluate their stiffness and reactivity. Glulam beams were evaluated by a bending test. The quality of the bonding was evaluated by resistance to shear and delamination. The morphology of the bonding was studied by microscopy. The DMA study showed that the MUF adhesive had the highest level of stiffness and reactivity. The results of the bending test showed that the highest modulus of rupture results were obtained in solid and hollow laminated beams with MUF adhesive, achieving increases of 30% over the PUR adhesive. The lowest delamination results were obtained in solid glulam beams with MUF and EPI adhesives, while the highest results were 32% and 47% for the PUR adhesive. Finally, glulam beams manufactured with MUF adhesive presented the best performance and results.
The paper discusses mechanical properties of timber for structures – most frequently used spruce wood, historically used oak wood and rarely mentioned larch wood. The main focus is on larch wood extracted from the ceiling of an immovable cultural monument from the 17th century – the determination of its age, its historical importance and mechanical properties. Mechanical properties were obtained by the standard tests in compression parallel and perpendicular to the fibres and in bending. The results of tests are compared to the mechanical properties of oak wood, of commonly used spruce wood and of recently felled larch wood.
In Brazil, some tile manufacturers have proposed a 10% (5.5°) slope between chords to minimize timber consumption. However, after simulating 21 slopes from 7% (4°) to 27% (15°), it was discovered that the axial strengths are inversely proportional to the slope, creating overly large dimensions for the bars competing for support. The results were obtained using software developed following the guidelines specified in the revised version of the ABNT NBR 7190 (2022) standard. Finally, it was found that the minimum slope until no reinforcement is needed for the string bars is 16% (9°).
In this study, the wood flour content's effect on the weathering performance of flat pressed WPC was investigated. The high density polyethylene was reinforced with four different wood flour content (10%, 30%, 50%, 70%). The weathering performance of WPC was determined by the 400 h of artificial weathering test. According to the results, the color change is inevitable as long as the wood flour is used as filler. Surprisingly, the highest color change was obtained from WPC containing 30% WF, contrary to 70% of wood flour. Similarly, the whiteness of the surface of WPC increased with exposure time. The photooxidation resulted in the chain scission and shorter molecules, which were observed by ATR-FTIR analysis. The changes in the intensity of characteristic polymer (2914 cm-1 and 2846 cm-1) and wood peaks (1510 cm-1 and 1027 cm-1) exhibited the photodegradation on WPCs' surface, which resulted in color change. Moreover, the light microscopy investigation showed surface degradation. The extensive weathering conditions caused surface cracks and surface roughness. The visual appearance of WPCs also demonstrated how to change the surface character of WPC during the 400 h of artificial weathering. In conclusion, the increase in the wood content increased the intensity of degradation.
In this paper, acidified chitosan was used as an adhesive to prepare aldehyde-free, environmentally-friendly agglomerated cork panels by hot-pressing. After preparation, the physical, mechanical, and the finishing properties of the chitosan-glued agglomerated cork panels were investigated. The optimal mass ratio of acetic acid solution (1 wt.%) to chitosan was determined to be 30:1. The resulting hot-pressed agglomerated cork panels, which featured a density of 0.55 g.cm-3 and a thickness of 4 mm, exhibited a tensile strength of 1.70 MPa and a thermal conductivity of 0.11 W.m-1•K-1. The agglomerated cork panels coated with the oil-based polyurethane and water-based, acrylic-modified polyurethane paints exhibited significantly lower lightness and higher glossiness. The total color differences (ΔE*) of both agglomerated cork panels increased before and after finishing. The oil-based polyurethane paint coating exhibited high adhesion of paint film, reaching a level-0 adhesion, while the water-based, acrylic-modified polyurethane paint coating achieved a level-1 adhesion. The abrasion resistance results showed that the substrates of cork agglomerates coated two types of paint did not expose after undergoing abrasion for 100 revolutions at the turntable speed of 60 rpm.
Parallel strand lumber (PSL) was manufactured from the veneer strand cut from the poplar broken veneers of the plywood enterprises, by analyzing the influence of the size of veneer strands, the glue concentration and glue-applying time on the glue-absorbing amount of veneer strands, the influence of three different glue-applying was, hot-pressing time and temperature on the physical and mechanical properties of PSL was reviewed and the hot-pressing technology was optimized. The experiment results showed that the size of the veneer strands have not notable influence on the gluing-absorbing amount, and mainly affect the homogeneity and appearance quality of the product. The glue concentration is one main factor to affect the glue-absorbing amount of veneer strands and PF resin of 30% concentration was chosen. The glue-applying way is the main factor to affect the mechanical property of PSL. The hot-pressing time and temperature have significant influence on physical and mechanical properties of PSL. Comprehensively considering, the physical and mechanical properties and homogeneity of products are better using the veneer strands with 100 mm length, the glue-spraying way and hot-pressing technology with the time 35 min and the temperature of 150°C.
The effect of surface roughness and water contact angle of commercial paperboard before and after surface modification by calendering, coating and calendering and plasma treatment on the functionality of UHF RFID antennas printed with thermal transfer aluminum ribbon was evaluated. A hydrophilic surface was created by coating or plasma treatment, which improved the wettability of the paperboard surface, the spreading of the thermoplastic tie layer and the adhesion of the conductive aluminum layer. A new paper product was created with permanent surface wettability by coating, without the need for plasma treatment before printing. The plasma treatment provided time-limited wettability, needed only during printing, and made it possible to restore the original hydrophobic surface of the paperboard. In addition to the meaning of these surface modifications, the importance and need to reduce the surface roughness was confirmed, as the higher surface roughness of the paperboard limited the effect of the plasma treatment in terms of its printability and the functionality of the printed aluminum antenna. The printability of the paperboard and the functionality of the printed antennas were evaluated using electrical conductivity. The electrical conductivities of the dipole and inductor loop of the UHF RFID antennas printed on modified paperboards varied…
A novel wood feature extraction method based on improved blocked higher-order local auto-correlation
Traditionally, HLAC (Higher-order Local Auto-Correlation) algorithm was used to extract texture features of wood images. However, heavy memory consumption and complexity of high-order mask pattern were common in HLAC. A novel feature extraction strategy based on improved blocked higher-order local auto-correlation (IBHLAC) is proposed to circumvent these problems. Initially, sequences of the whole wood image frames, which are the grayscale treatment, were being divided into series of subdivisions vertically and horizontally. Additionally, to enhance auto-correlation ability of the proposed method, different high-order patterns of masks were rebuilt based on zero-order mask by introducing the morphology and affine transformation. Finally, time-consumption and memory occupation of related four methods were compared. Experiment results indicated IBHLAC costs less time and fewer memory consumption on the wood texture database compared with other methods, which reveal that IBHLAC is efficient.
Our study is interested in isolating fungi from the wood parts of cedar trunks withered and identifying these lignivorous fungi. A sample was isolated from the cedar grove of Tazekka National Park located south of the city of Taza in Morocco. The culture and purification of the isolated fungus were done on a water agar medium and then on a PDA medium. After the purification of the fungus, a morphological study by electron microscope allowed us to identify the pathogen Pleurostoma richardsiae. A molecular characterization confirmed these results with a coverage percentage of 97% and an identity of 99%. To our knowledge, this is the first report of P. richardsiae in decayed cedar wood.
WOOD RESEARCH Volume 67, Number 5
The plant grows within the transportation of water and nutrients, including radial and longitudinal, but bamboo only exists pits in the radial, so it plays an irreplaceable role at this moment. This study aims at giving rise to further understanding of the biological functions of pits in bamboo. Light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were applied to investigate the structure and connections of bamboo pits. The results show that the arrangement of pits is significantly different, including alternate, scalariform and opposite arrangements. The presence or absence of the bordered on different cells is also displayed distinctively, these characteristics extremely affect the transportation of water and nutrients in bamboo.
The main aim of this study was to determine differences in basic density and average annual ring width of pendulate oak wood collected from trees grown on former agricultural land and on forest land, using a dimensional method. The experiment was carried out in the western part of Poland, near to Poznan, which is in the central part of the European range of pedunculate oak. In our study the average basic density was 0.528 g.cm-3, and the value for former agricultural land was lower by 0.026 g.cm-3 than that for forest land. Differences in basic density values between these two land types were statistically significant. The average annual ring width in samples collected from forest land in our study was 2.48 mm, samples from former agricultural land were characterized by wider average annual rings. The results suggest that there are significant differences in quality of wood from former agricultural land and from forest. However, from view of wood quality and applications the difference is not important.
In this study, samples of bamboo and carbonized bamboo were impregnated with alkaline copper quaternary (ACQ) and water glass, the resulting differences in color and resistance to decay by Gloeophyllum trabeum were evaluated. The results showed that the impregnated bamboo and carbonized bamboo greatly reduced their lightness (L*). The red-green color index (a*) first decreased and then increased, while the yellow-blue color index (b*) first increased and then decreased. The total chromatic aberration (ΔE) was largest for bamboo and carbonized bamboo impregnated with ACQ and allowed to decay. Carbonized bamboo impregnated with ACQ and water glass and bamboo impregnated with ACQ reached level I (strong decay resistance). The decay resistance of bamboo and carbonized bamboo was as follows: ACQ impregnated > water glass impregnated > CK. Scanning electron microscopy further confirmed that the bamboo and carbonized bamboo were impregnated with ACQ had fewer hyphae, the maintained intact structure, and good decay resistance.
To investigate the effect of Zelkova schneideriana surface cracks on the longitudinal wave propagation characteristics of acoustic emission (AE). Different sizes and numbers of cracks were made on the surface of the specimen, the propagation characteristics of AE longitudinal waves along wood texture direction were studied. Firstly, five regular cracks with the same length, different width, depth and equidistant distribution were fabricated on the surface of the specimen. The burst and continuous AE sources were generated by lead core breakage and signal generator, and the AE signals were acquired by 5 sensors with sampling frequency was set to 500 kHz. Then, the propagation speed of AE longitudinal wave was calculated by Time Difference of Arrival (TDOA) based on lead core breakage. Finally, the 150 kHz pulse signals of different voltage levels generated by the signal generator were used as AE sources to study the influence of cracks on the attenuation of AE longitudinal wave energy. The results showed that the AE longitudinal wave propagation speed under the crack-free specimen was 4838.7 m.s-1. However, after the regular crack was artificially made, the longitudinal wave speed reduced to a certain extent, and the relative error of the change was not more than…
In this study, vegetable oils were selected to modify poplar with vacuum-pressure impregnation technology and the optimum progress was studied. The weight percent gain (WPG), modulus of rupture (MOR), modulus of elasticity (MOE), water uptake rate (WUR), volume swelling rate (VSR) and volume shrinkage rate (VSR') were evaluated. The results showed that the dimensional stability, physical and mechanical properties of treated wood were significantly improved. Scanning electron microscopy (SEM) observations revealed that castor oil was inserted into the interior of the wood through the pores. Vegetable oil modification (castor oil) decreased the intensities of hydroxyl, cellulose and hemicellulose specific peak in the Fourier transform infrared spectroscopy (FT-IR) results. The Fourier transform infrared spectroscopy (FT-IR) results showed that castor oil treatment decreased the intensities of hydroxyl, cellulose and hemicellulose specific peak. Ultimately, the optimum process of castor oil treatment was impregnation pressure 1.8 MPa, time 1.0 h and temperature 85°C based on the range and variance analysis.
In the present study silicon containing formulations were investigated for their applicability in solid wood modification. Black pine sapwood was thermally modified at 180oC and 200oC (3, 5 and 7 hours) and afterwards, an additional chemical treatment with silicon containing systems (N-2-aminoethyl-3-aminopropyltrimethoxysilane) followed, in an attempt to invigorate hydrophobicity and durability of wood. Infrared spectroscopy (FTIR) was used to examine the formation of new bonds in the treated materials and atomic absorption spectrometry (AAS) to measure the silane concentration. The results showed a high reactivity between thermally modified wood and organosilicon compounds. The presence of bands representing vibrations of the Si–O–CH3 group in IR spectra of modified wood and after extraction confirms the stable character of the formed bonds between the hydroxyl group of wood and the methoxy groups of organosilanes. Furthermore, reactivity between wood and AE-APTMOS and alkyd resin solution was confirmed by the AAS results. Alkyd resin caused a higher concentration of silica in wood mass, which increases as the thermal treatment temperature increases. The organosilicon compounds caused a much higher resistance to water washout, revealing permanent binding of silanes to wood mass.
After the production cycle of latex, Hevea brasiliensis trees become residual living plants for this activity, although their woody trunks are still potentially subject to industrial utilization. Bio-composites derived from rubberwood particles were manufactured using two different configurations as a strategy to examine the potential of this species with respect to mechanical behavior. Homogeneous panels were developed from particles at the saturation condition, and heterogeneous panels were obtained from dry particles conditioned at 12% moisture content. Both examples were heat-pressed and glued with castor oil-based polyurethane resin. Density,short-term water absorption and thickness swelling, modulus of rupture and modulus of elasticity in the static bending and perpendicular tensile were evaluated. Panels derived from rubberwood particles proved to be viable according to the technical standards.
Research on improving the reactivity of phenol-formaldehyde (PF) resin and the possibility of lowering the pressing parameters of wood-based materials manufactured with its participation are still progressing. Due to a number of favorable properties, nanocellulose (NCC) is gaining more and more popularity as a modifier of wood adhesives. Therefore, the objective of the study was to assess the possible reduction of plywood pressing parameters due to the reinforcement of PF resin with NCC. Based on the bonding quality results it was found that there is a possibility to reduce pressing time by 25% and pressing temperature by 7%. Moreover, the outcomes of mechanical properties (modulus of elasticity and bending strength) of manufactured plywood indicate that theoretically it could be possible to decrease the pressing parameters even more. However, the shear strength of the glue joints was considered to be a limiting factor for further reduction. The results of delamination test show that plywood bonded with phenolic resin have no tendency to delaminate. Thus, it can be concluded that NCC can be used as a modifier for PF resin which can contribute to the reduction of pressing time and pressing temperature during the plywood manufacturing process.
The mechanical properties of CLT manufactured from densified low-density planted timber, Paraserianthes falcataria were studied in relation to changes in the area of pores for under densification. Conditioned laminas (MC ≤ 15%) underwent two-stage densification using hot-press machine at 105oC, 6 MPa, for 10 min each, with press released for 1 min 40 sec in between the stages, before cooling (< 100oC) to reduce immediate springback. The laminas with thickness 8 mm, 10 mm, and 15 mm were produced using metal stoppers and further manufactured into three-layered CLT of 24 mm, 30 mm, and 45 mm thick. 20 mm undensified laminas with 60 mm CLT as the control. Results shows that modulus of elasticity (MOE), modulus of rupture (MOR), and compression parallel to grain have improved significantly and showed negative correlation with area of pores, except for compression perpendicular to grain.
In this work, a nano TiO2-FA/balsa wood-based composites were successfully fabricated by mechanical stirring assisted vacuum impregnation method, and the influence of different impregnation pressures on the microstructure, nanomechanical characteristics and photocatalytic performance of obtained composites were investigated. Results show that the nano TiO2-FA compound modifier was impregnated in the tracheid and attached to the wood cell walls. SEM revealed that the size of TiO2 nanoparticles grow larger as the impregnation pressure increases, and the presence of TiO2 globules with some areas agglomerated on the wood cell wall surface. Compared with the unmodified wood, the elastic modulus of cell walls for nano TiO2-FA/balsa wood composites prepared under 0.45 MPa significantly increased by 160.5%, and the hardness improved from 0.36 ± 0.04 GPa to 0.84 ± 0.08 GPa. Furthermore, the UV-Vis showed that the composite exhibited a high removal rate of methylene blue (10 mg.L-1), up to 88.74% within 240 min.
In this study, pumice powder as a volcanic aggregate was added in the particleboards' production. The effect of various ratios of pumice powder (10%, 20%, 30%, and 40%) on physical, mechanical, thermal and fire resistance properties was investigated. Pumice powder did not significantly affect particleboards' water absorption and thickness swelling values. However, the mechanical properties were significantly affected with raising pumice powder content. The modulus of rupture and modulus of elasticity decreased up to 46% and 45%, respectively. There was also a decrease in the internal bond strength up to 42%. Conversely, pumice powder improved the thermal degradation temperatures. The onset temperatures increased with increasing pumice powder content above 300°C. Similarly, the pumice powder improved the fire resistance of particleboards up to 7% compared to control samples.
This study evaluates the characteristics of superior clones of Eucalyptus pellita and Acacia hybrid (Acacia mangium × A. auriculiformis) aged six years selected from a breeding program in Indonesia as materials for pulp and papermaking. Height, diameter, and wood density differed significantly between species and among the clones, with respective mean values 21.6 m, 12.57 cm, and 657 kg.m-3 for E. pellita and 19.5 m, 24.83 cm, and 567 kg.m-3 for Acacia hybrid. Most fiber morphologies were significantly different between species. Cellulose and lignin differed significantly only among Acacia hybrid clones. The mean value of screened pulp yield Acacia hybrid (52.50%) was higher than that of E. pellita (50.31%). Kappa number and brightness were significantly different between species and among E. pellita clones. Some correlations of growth and wood properties showed a better relationship to pulp properties. Handsheet properties varied between species, and some clones showed an outstanding one.
The objective of this study was to evaluate the moisture profile and drying period of air drying the red pine and Japanese larch timbers with the cross section of 14.0 cm × 14.0 cm and 16.5 cm × 16.5 cm by measuring the electric resistance of the wood. The drying curves determined by measuring electric resistance and by oven-dried method were nearly identical at last drying stage, and had almost same moisture profiles and same drying period after the end of air drying. Therefore, the drying curve determined by measuring electric resistance can be used to predict the drying period and moisture profile of air drying the red pine and Japanese larch timbers with large cross sections.
Plant sap flow is crucial to understanding plant transpiration, plant hydraulic functioning and physiological properties. In this study, a method for predicting trunk sap flow of Larix olgensis using deep learning was proposed. The method is based on the combined use of Long-short term memory network (LSTM) and transformer model, noted as LSTM-transformer model. The experimental results show that the proposed method provides more accurate prediction quality in terms of correlation coefficient (R2), root mean square error (RMSE) and mean absolute error (MAE), compared to the state of the art forecast methods such as BP, DNN, LSTM, and transformer models.
This study focused on evaluating the physical properties of wood from photographs displayed on a monitor. Sample photos of 475 hardwoods and their physical information were collected from a wood database. R, G, and B values were extracted from the wood photos using color picker software. Statistical techniques such as Pearson's correlation coefficient and multiple regression analysis were applied to investigate relationships between wood color and physical properties. From results of Pearson's correlation coefficient, R, G, and B values were most affected by specific gravity. In a multiple regression analysis, tree size, specific gravity, and modulus of rupture (MOR) were significant in the positive (+) direction by color (R, G, and B). On the other hand, modulus of elasticity (MOE) was significant in the negative (-) direction at the 1% level by color. The specific gravity of wood had the most significant effect on R, G, and B values in multiple regression analysis. In conclusion, the color and specific gravity of wood were related closely. Additionally, it is possible to predict the physical properties of wood from the R, G, and B values of a wood sample photograph displayed on a monitor. These results could provide useful information for wood…
WOOD RESEARCH Volume 67, Number 6
This study deals with the investigation of impact of temperature and ultraviolet (UV) radiation on spruce wood (Picea abies (L.) H. Karst.) and fir wood (Abies alba Mill.) colour changes. Samples of investigated woods species were loaded by temperatures of 110, 130, and 150°C and UV radiation (with 253.7 nm wavelength and 40 W m-2 intensity) during 72, 168, 336 and 672 hours. Colour changes were evaluated in the CIE Lab colour space. The neural network for prediction of both colour coordinates and total colour difference of spruce and fir wood was trained by data regarding exposure conditions (temperature, UV radiation and time) and by obtained results. Coefficient of determination (R2) of the neural network was above 0.99 for training, validation and testing. Average colour coordinates (± standard deviation) of the spruce and fir wood before exposure were L* = 80.08 ± 3.70, a* = 7.55 ± 2.13, b* = 21.56 ± 1.79, L* = 80.46 ± 1.91, a* = 6.84 ± 0.97, and b* = 18.90 ± 1.26, resp. Total colour differences after thermal loading were in the interval from ΔEab* = 3.76 ± 1.95 (spruce wood at 110°C) to ΔEab* = 45.37±1.46 (fir wood at 150°C). Total colour…
Wood collapse is a major defect for their applications in solid wood production. Supercritical CO2 (ScCO2) dewatering can quickly remove water in wood and effectively reduce the capillary tension leading to collapse of wood structure. In this study, Eucalyptus exserta F.V. Muell wood was dewatered using ScCO2 at 35, 45, 55°C and 15, 20, 25 MPa, separately. The dewatering characteristics and wood deformation were statistically analyzed and compared after dewatering. The results show that the dewatering rate of ScCO2 is affected by moisture content (MC) of wood, showing the higher the MC, the faster the dewatering. It is also affected significantly by pressure, indicating increased dewatering rate with the pressure. The effect of temperature on dewatering rate is not apparent as the pressure is less than 25 MPa, but it becomes significant at 25 MPa condition, showing an increased dewatering rate with temperature. In this experiment, the greatest dewatering rate was 19.8%·h-1 at 55°C and 25 MPa. The transversal shrinkage of all specimens after 5 cycles dewatering was lower than 1.5%, indicating the ScCO2 dewatering could effectively inhibit collapse of eucalyptus wood structure. The transversal shrinkage decreases with the pressure, and is not affected significantly by temperature.
The main aim of this study is to define the usability of the confocal scanning optical microscope (CSOM) to evaluate the wood surface roughness. Therefore, systematic investigation was carried out to define the influences of CSOM on the acquisition of 2D surface roughness parameters. Mahr Perthometer was applied to get reference data to estimate the applicability of the CSOM. Because wood roughness parameters measured with stylus and optical methods are not always comparable a calibration method was conducted on a metal calibration etalon. After the calibration process, the roughness profiles taken with the optical and stylus units were much closer to each other and only the optical Rpk parameter was definitely higher due to artificial peaks generated by the optical system. In order to eliminate this measuring failure, the morphological filter option of the optical apparatus may be activated. The surface roughness parameters were measured on planed Scotch pine samples. The planed surface plains were produced with 0.2 mm parallel offset to investigate the structural influence of the single cutting plains. The obtained results show that the average values for Ra, Rq, Rz, Rk, and Rvk are close to each other for both measuring systems, only the optically measured Rpk…
The main objective of the study was to investigate the effect of mixed acid concentration on the morphology, crystallinity and thermal properties of cellulose nanocrystals (CNCs). Acid hydrolysis using mixture of sulphuric (H2SO4) acid and perchloric (HClO4) acid was used to extract CNCs from sugarcane bagasse (SCB). The properties of the raw SCB, extracted cellulose, 45% H2SO4 hydrolysed CNCs, 45% H2SO4/HClO4 hydrolysed CNCs, 55% H2SO4/HClO4 hydrolysed CNCs and 65% H2SO4/HClO4 hydrolysed CNCs were analysed using Fourier transmission infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The crystallinity of SCB was significantly increased after bleaching and acid hydrolysis. Acid hydrolysis using 55% H2SO4/HClO4 showed the highest crystallinity. The TGA results showed significant increase in thermal stability of 55% H2SO4/HClO4. The lowest thermal stability was observed with 45% H2SO4 hydrolysed CNCs. The order of thermal stability was raw SCB < extracted cellulose < 45% H2SO4 hydrolysed CNCs < 65% H2SO4/HClO4 hydrolysed CNCs < 45% H2SO4/HClO4 hydrolysed CNCs < 55% H2SO4/HClO4 hydrolysed CNCs. The SEM results showed fibre breakage for 65% H2SO4/HClO4 hydrolysed CNCs. The fibre breakage seemed to be acid concentration dependent.
In this paper, ammonium phosphate polymer (APP), guanidinium phosphate urea (GUP), phosphonic acid, and a small number of additives that confer flame retardant properties were prepared as a new composite flame retardant. Cedar (Cryptomeria japonica) and hinoki (Chamaecyparis obtuse) penetrate and absorb the solution into the inner wall of the wood by vacuum pressurization, thus obtaining fire-retardant woods. The flame retardant effects at different absorption amounts were investigated by thermogravimetric analysis and cone calorimetry. The absorption amounts of both kinds of wood above 0.095 g.cm-3 and 0.085 g.cm-3 respectively, met the flame retardant standard ISO-5660-1: 2015. Thermogravimetric analysis showed that the fire-retardant-treated wood increased thermal stability, accelerated carbonization, and lower the decomposition temperature to below 300°C.
This research was focused on the effect of water content in the cells of disintegrated Populus nigra L. on a freeze-thaw pretreatment method before an enzymatic hydrolysis. Two chipped and sieved fractions 2.5 mm and 0.7 mm and two milled fractions, characterized as 18°SR (Shopper–Riegler index) and 37°SR, of the disintegrated 5 years old poplar tree were used for our experiment. Glucose and xylose yields were measured after 24 and 48 hours of enzymatic hydrolysis with a 15% load of the enzyme measured to a total cellulose content. The influence of nine freeze-thaw cycles under -20°C and +20°C was considered. The results showed that an increase in moisture content positively affects yields in all fractions but a desirable result was achieved mainly for the 0.7 mm fraction where the total yield increased by about 16%. More effective way is a finer wet beating of wood mass, while wood fibre receives moisture already in the technological process. The highest glucan conversion 51,74% and the total hemicelluloses conversion 47,72% was achieved for the finest fraction 37°SR. The higher moisture content has a positive effect on the increase in the conversion of oligosaccharides, especially glucan, in chipped fractions.
Artificial AE sources were generated on the surfaces of Ulmus pumila, Zelkova schneideriana, Cunninghamia lanceolata, and Pinus sylvestris var. mongolica Litv. specimens. The AE transverse wave signal was decomposed into 3-layers detail signals by wavelet decomposition and reconstructed, and it was calculated based on correlation analysis. Then the longitudinal wave speed was calculated according to the time-difference-of-arrival (TDOA) method, and the wood dispersion phenomenon was studied. The results showed that the dispersion phenomenon of Ulmus pumila was obvious. The propagation speed of high-frequency signal was 2.38 times that of low-frequency signal. The ratio of high and low frequency propagation speed of soft wood was 1.72 and 1.73. The dispersion degree of Zelkova schneideriana was the weakest, and the propagation speed of the high frequency was 1.25 times of the low one. The ratios of longitudinal and transverse wave speeds of the four specimens were 4.59, 4.07, 4.24 and 4.2, respectively.
In this paper, the energy absorption of single-wall corrugated fibreboard with a trapezoidal core under edgewise crushing load was studied experimentally and analytically, and a physical surface bonding was assumed to represent the interaction between the fluted board and the linerboard based on the production process of corrugated fibreboards. A new folding element was proposed, including two boards and two trapezoidal corrugated cores with central symmetry. Moreover, three folding modes of the fluted board were proposed based on experimental phenomena, and a plateau stress model was characterized by the geometry parameters of the corrugated fibreboard. It was found that the plateau stress predicted by the developed model compared well with the experimental results, from which one can conclude that the proposed model was effective and helpful for corrugated structures design and parameters selection to meet different strength requirements.
Influence of wood species on quality of exterior transparent acrylic coating during outdoor exposure
Coating systems are a popular way to protect wood against the effects of weathering when used outdoors. This study evaluates the impact of the basic wood species on the overall durability and color fastness of the selected water-based acrylic exterior paint. Spruce (Picea abies L.) and oak (Quercus robur L.) wood samples were subjected to external weathering according to EN 927-3 (2000) for 6 and 12 months. The evaluation by instrumental methods related to co changes in color, gloss, surface wettability contact angle, at which paint damage was also visually evaluated. The results showed that the durability of the tested coating was higher for spruce. Still, on the other hand, thanks to its lighter shade, a significant color change caused by the base wood's photodegradation was detected, showing that oak wood has a negative effect on the overall life of the tested coating.
The paper deals with theoretical and experimental research of the timber connections using modern timber connectors Rothoblaas Alumidi. These connectors allow for semi-rigid behaviour of the connections. The paper describes the theoretical background of semi-rigid connections, explains the methods used in the numerical analysis and the design of test connections. The thesis continues with the experimental verification of the designed specimens. The experimental results are compared with the numerical analysis. The findings obtained from the experiment and recommendations for practice are summarized in the conclusion.
In this study, sandwich panels made from oil palm lumber, sengon, and gmelina wood were impregnated with a boron-alum solution to improve their water and termite resistance. Water resistance testing was evaluated using a thickness swelling test following the method in SNI 03-2105. The sandwich panel was also tested for its durability against dry wood termites, according to SNI 01-7207. The weight loss, mortality, and attack degree were used as the parameters for evaluating termite durability. The results showed that the treatment with a boron-alum solution can increase the stability, water resistance, and weight loss properties up to 73%, 41%, and 100%, respectively. The best properties of the sandwich panel were obtained by the sengon-isocyanate panel with 8% boric acid-borax and 5% alum treatment which has thickness swelling of 2.37%, water absorption of 49.04%, weight loss of 0.0124%, termite mortality of 100%, and attack degree of 0.
In this study, a modification combining densification and heat treatment of poplar wood (Populus tomentosa Carr.) was carried out, and the machining properties of the unmodified poplar wood (control) and the heat treated densified wood (HTD) were tested and evaluated. In addition, the water-based UV paint was covered on the control and HTD respectively, and the surface coating properties of them were evaluated. The results showed that: (1) The machining properties of poplar wood were improved after the heat treatmentdensification modification. The score of comprehensive machining properties of the HTD was 45 (excellent grade), while the score of the control was 36 (good grade). (2) The abrasion resistance, hydrophobicity and adhesion were improved after heat treatment-densification modification. Therefore, the modification combining densification and heat treatment played a significant role in enhancing the value of wood.
The softening process of wood bending has a very important influence on the performance, forming shape, and yield of bentwood. The paper reviewed the typical softening processes in solid wood bending by analyzing the various softening mechanism and softening processes. The main influencing factors of the softening technology on the bending properties were summarized based on the comparative analysis of the related research progress of wood softening. In view of the lack of systematic analyses of the cost and environmental factors associated with the softening process, this paper goes in detail analyzing the major softening technologies with comprehensive comparison of the economic and environmental advantages and disadvantages. The paper also draws light on the development trends of softening technology that can be implemented in wood industry which can hence improve the added value of wood. Under the background of green development, the authors believe that the softening technology should not only benefit the economic efficiency but also meet the social needs of low-carbon and environment-friendly.
Nine-ply plywood panels were produced from Eucalyptus grandis and Populus deltoids using urea-formaldehyde (UF) and phenol-formaldehyde (PF) adhesives. The physical and mechanical properties, such as moisture content, density, modulus of rupture (MOR) and modulus of elasticity (MOE) of the eucalyptus and poplar boards, were compared in this study. Samples were tested on both, along and across the grain. Higher values of MOR and MOE were observed for eucalyptus as compare to poplar. Density of ply board was observed as 500-560 kg.m-3 in plywood from poplar and 700-720 kg.m-3 in plywood from eucalyptus species. These differences were attributed to the variation in properties of veneer wood species. The effect of veneer wood species on some physical and mechanical properties of plywood was found statistically different.
Volume 66 (2021)
WOOD RESEARCH Volume 66, Number 1
Our paper proposed an ensemble framework of combining three deep convolution neural networks (CNN). This method was inspired by network in network. Transfer learning used to accelerate training and deeper layers of network. Nine different CNN architectures were trained and evaluated in two wood macroscopic images datasets. After two times of 30 epochs training, our proposed network obtained 100% test rate in our dataset, which including 8 kinds of wood species and 918 images. The proposed method achieved 98.81% test recognition rate after three times training with 30 epochs in other dataset, which including 41 kinds of wood species and 11,984 images. Results showed that magnification macroscopic images can be instead of microscopic images in wood species identification, and our proposed ensemble of deep CNN can be used for wood species identification.
The paper investigates efficiency of silicate flame retardants on wooden fibres (used for production of medium-density fibreboards) and spruce boards. A simultaneous thermal analysis and cone calorimetry were used for the assessment. Specimens were treated with three different types of silicate water glass: sodium silicate, potassium silicate and modified silicate. Along with these, one sample of untreated fibres was tested in order to provide a baseline sample. As a result of the simultaneous thermal analysis, the ability of the treatments to increase the residual amount of biological char in samples during pyrolysis and ability of the flame retardant to be retained in these wood fibres was used to assess the efficiency of each flame retardant on the wood fibres.
Effect of loading type (compression and tension) on mechanical properties, including elastic constants, yield strength and ultimate strength of beech (Fagus orientalis) wood were studied based on experimental and numerical methods. The mechanical behaviors of beech wood in compressive and tensile states were simulated by finite element method (FEM) using mechanical parameters measured in an experiment. The results showed that the effect of loading types on mechanical properties of beech was statistically significant. The elastic moduli measured in tension were all bigger than those in compression, but the Poisson’s ratios determined in compression were bigger than those in tension. In compressive state, the yield and ultimate strengths of beech in longitudinal grain orientation were all smaller than those measured in tensile state, while the yield and ultimate strengths of beech in radial and tangential directions were higher than those of longitudinal direction. The results of the FEM in compression and tension were all well consistent with those measured by experiments respectively, and the average errors were all within 13.69%. As a result, the finite element models proposed in this study can predict the mechanical behaviors of wood in tensile and compressive states.
The concentration of selected heavy metals: chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu) and zinc (Zn) in 5-year-old wood of Populus trichocarpa before and after steam explosion (SE) and liquid hot water (LHW) pretreatments was studied. The concentration of the above heavy metals in the liquid fraction obtained after pretreatments was also studied. The studied problem of heavy metals in lignocellulosic biomass is an interesting and important issue in the context of bioethanol production technology. An X-ray fluorescence spectrometer (XRF) was used to analyse the concentration of heavy metals. The change of concentration of the tested elements in wood biomass after pretreatment was small (except for iron). On the other hand, the average concentration of iron in wood biomass of a 5-year-old Populus trichocarpa, after SE and LHW with duration of the pretreatments 15 and 60 min, increased about 24-fold to 28-fold, comparing to its average concentration in native wood. During the pretreatment process, wood biomass absorbed the iron that at high temperatures passed from the pretreatment equipment to the solution. The average concentration of the elements under research in liquid fraction obtained during SE and LHW of wood biomass with duration of the pretreatments 15 and…
In this study, the biodegradable composites were prepared from rubber wood fibers (Hevea brasiliensis) and biopolymer poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) via hot pressing process, using the titanate as the coupling agent. The morphological, chemical structure, mechanical properties and water absorption (WA) of the composites were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), mechanical properties and WA analysis. Results showed that a new absorption peak of Ti-O-C was formed due to the addition of titanate, indicating that it was successfully grafted on the surface of wood fibers. In addition, the mechanical properties of the composites first increased and then decreased with the increasing of the titanate content. The obvious improvement of WA of composites was attributed to the inclusion of P34HB by titanate modified wood fiber. Moreover, it was also found that the optimal condition of the titanate coupling agent content was 1 wt%.
This study investigated the antioxidant activity from the methanol (MeOH) soluble extract of the inner and outer bark of Swietenia macrophylla. The MeOH soluble extracts were fractionated into ethyl acetate (EtOAc) soluble and insoluble. The antioxidant activity was conducted by DPPH (1,1-diphenyl-2-picrylhydrazyl) method and the phenolic compounds were detected by GC-MS. The levels of total phenolic content of soluble and insoluble fraction of EtOAc of outer bark were higher than in inner bark, while total flavonoid content showed opposite results. The crude methanol extract and its EtOAc soluble fraction of outer bark showed a higher level of antioxidant activity. The GC-MS analysis detected higher levels of fatty acids and alcohols of 87.12% than phenolic compounds of 12.17% in the inner bark, while the outer bark showed the opposite pattern with phenolic compounds of 82.65% than fatty acids of 8.43%. A strong correlation was demonstrated between total phenolic content and antioxidant activity.
UHF RFID printed antennas on conventional and experimentally coated papers by thermal transfer and inkjet technique were not conductive due to high surface roughness. Reducing the surface roughness of paper and hence the electrical resistance of the antennas printed by thermal transfer and inkjet printing was achieved by coating and subsequent calendering process. Papers for thermal transfer and inkjet printed of aluminum and silver antennas were prepared by coating with top functional coating, whose main component was pigment - precipitated calcium carbonate with addition of polyvinyl alcohol, cationic polymer PDADMAC and glyoxal. The desired quality of inkjet-printed silver antennas was achieved by using coated paper with a polyvinyl alcohol barrier layer and a top functional hydrophilic layer. Silver nanoparticles of inkjet ink require a sintering process to obtain a conductive printed trace. The microstructure and thickness of antennas printed by thermal transfer and inkjet technique were compared. Thermal transfer printing created a more homogeneous antenna with greater sharpness of drawing compared to inkjet printing.
This study investigates the effect of silica on sugarcane bagasse (SCB) and softwood (SW) cellulose. Cellulose was extracted from raw SCB and SW chips using a three-step process, namely thermal pre-treatment, alkaline treatment and bleaching treatment. Alkali treated cellulose was then subjected to silica surface modification using the solvent exchange method. The effect of silica modification on SCB and SW cellulos was investigated using X-ray diffractions analysis (XRD), Fourier transform infrared (FTIR) spectroscopy and optical microscope (OPM) techniques. Both the FTIR and XRD results confirm successful extraction of cellulose from both raw fibers and addition of silane functional groups in the cellulose surface. XRD patterns of all samples revealed typical spectra for natural fibers corresponding to crystalline peaks of cellulose and undissolved amorphous hemicellulose respectively. SCB and SW showed similar increasing patterns of crystallinity with nanosilica surface modification. The surface morphology results showed that both SCB and SW cellulose modified with silica were swollen and displayed small particles agglomerating on the surface of the fibers. The solvent exchange method proved to be a successful method for modifying SCB and SW cellulose with nanosilica. It also proved to be cost-efficient and time-efficient.
Ailanthus wood (Ailanthus desf.) was thermally treated at three different low temperatures (140, 160, 180°C) for 2 and 4 h in order to investigate the effects on wood color, hygroscopity and dimensional stability. Results indicate that mass loss increased following the treatments, while equilibrium moisture content decreased from 11.86% to 9.88% for the 180°C and 4 h treatment. Moreover, improvements in the dimension stability were observed for post-treatment samples. The thermal treatment induced color changes in the Ailanthus wood, with a significant reduction in the lightness, yet the redness and yellowness exhibited minimal changes. FITR spectra of the thermally treated wood suggest that the heat treatment resulted in the deacetylation of hemicellulose. These results help to conclude that thermal treating temperature under 160°C can improve wood dimensional stability and maintain original color.
The paper presents changes in the color and acidity of Fagus sylvatica L. in the process of heat treatment of wood with saturated water steam in the temperature range t = 105 – 135°C during τ = 3 to 12 hours. The light white-gray color of beech wood with a yellow tint changes on the pale pink, red-brown to a brown-red color in the heat treatment process. The color changes of beech wood expressed in the form of the total color difference are in the range of values ΔE* = 1.97 – 26.85. Due to the hydrolysis of hemicelluloses, the acidity changes in the process of thermal treatment of wet beech wood. Decrease in acidity of beech wood in the range of temperatures t = 105 – 135 °C and time τ = 3 – 12 hours is in the range of pH values = 4.9 to 3.4. The dependence of the total color difference ΔE* on the change in acidity of beech wood is described by the polynomial of function II. degree. The above knowledge is a suitable tool for evaluating the degree of change in beech wood color in the technological process based on the change in pH…
The aim of this work was to compare the general, physical, mechanical, chemical and energy properties of the wood from Cedrela odorata trees growing in two agroforestry condition (tree-agroforestry) with Theobroma cacao (9 and 10 years old), with a ten-year-old C. odorata tree growing in pure plantation (tree-plantation). The results showed that there growing in agroforestry presented higher heartwood diameter (6.7 to 7.6 cm) and heartwood (approx. 17%) and lower bark (12-13%) and sapwood (69-70%) percentages than trees in pure plantation. In addition, this tendency was observed through different heights of the tree. Moreover, wood from 9-tree-agroforestry presented highest specific gravity and volume shrinkage. Then wood from this growing condition presented highest strength in axial hardness and flexure relative, and extractives in cold water and ethanol-toluene. No differences were observed between the energy properties. In general, wood from trees in agroforestry present better properties than the trees growing in pure plantation. According with these results, the potential of agroforestry systems relative to pure plantations, as regards to differences in tree growth produced by crop fertilization, pruning and other management measures to which the agricultural crop is subjected, which can give the wood qualities different from those found at earlier ages.
This research aims to investigate the effect of thermal modification by hot pressing on surface characteristics of rubberwood. For this purpose, rubberwood specimens were thermally modified by hot pressing in an open system at three different temperatures (170, 185, and 200°C) for two different durations (1.5 or 3 h). Based on the results, the values of chromatic aberration (ΔE), contact angle and glossiness increased, and roughness decreased with increasing temperature and enlarging duration further. Although the contact angle had increased, it was still less than 90°. This aesthetic surface of rubberwood could be retained by using transparent organic coatings. The thermally modified rubberwood with excellent performance could be used as a material for solid wood flooring, wallboard, and furniture applications.
Through the time-frequency analysis of the propagation waveform of the acoustic emission (AE) signal propagating in the thin sheet of Pinus sylvestris var. mongolica, the propagation characteristics of the stress wave when propagating as a lamb wave was studied. An AE source was generated on the surface of the specimen, the discrete wavelet transform method was used to achieve AE signal de-noising and reconstruct the waveform of the AE signal. On this basis, the time difference positioning method was used to calculate the propagation velocity of lamb waves, and compared with the propagation characteristics of lamb waves in the metal specimen. The results show that the high-frequency mode of lamb waves attenuated sharply as they propagate in the thin wood sheet, indicating that the microstructure of wood has a significant low-pass characteristic for lamb waves. The average attenuation rates of lamb waves in metal and thin wood sheet were 87.1% and 75.7%, and the velocity was 4447.0 m.s-1 and 1186.3 m.s-1, respectively. This shows that AE signals can travel longer distances in the thin wood sheet, but the propagation velocity is significantly reduced.
This study compared the magnitude of the value of the cutting force using different tools with different thickness for different wood species with the same size. Measurements were made on wooden samples of spruce, aspen, and beech wood with dimensions 30 × 30 × 200 mm (w × d × h). The tearing machine pushed knives with dimension 150 × 100 mm and thicknesses of 4, 6, 8, and 10 mm with a 30° angle of cutting edge into the wood samples in a direction perpendicular to the fiber growth. Research shows that this angle of cutting edge is most effective for chipless cutting. The results were analysed by the Statistica 12 software. From the measurement results, for chipless wood felling is most preferred the 10 mm cutting knife thickness.
In this work, resol type phenol–formaldehyde (RPF) resin was modified with silicon dioxide nanoparticles (SiO2-Np). SiO2-Np was added at varying ratios from 1 to 4 wt.% to improve the bonding performance of the RPF resins. The physical characteristics of the nano-modified RPF (nano-RPF) resins were examined. The effects of modification were studied by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The results of FT-IR revealed that the nano-RPF resins were successfully produced by phenol, formaldehyde, and SiO2-Np. The nano-RPF resins demonstrated high thermal stability at temperatures above 500°C. The adhesive performance of the nano-RPF resins was investigated under dry and wet conditions. The nano-RPF resins indicated better adhesive performance than unmodified RPF resin. The RPF resin could be improved by SiO2-Np.
WOOD RESEARCH Volume 66, Number 2
Herein, we evaluated the content of condensed tannins present in the bark of four tree species that are Quercus laurina Humb. & Bonpl., Quercus crassifolia Humb. & Bonpl., Arbutus xalapensis Kunth, and Prunus serotina Ehrn. An analytical method using high-performance liquid chromatography (HPLC) for condensed tannin extracts was developed and validated. Also, the aqueous extracts were analyzed by Fourier transform infrared spectroscopy (FTIR). Based on the Stiasny number, A. xalapensis, and Q. laurina represent an important source of condensed tannins, which may be subject to exploitation. Using infrared spectroscopy, it was observed that tannins do not show an important signal of carbonyl groups (aromatic esters) with respect to high purity catechin. Furthermore, the band of the hydroxyl group is less pronounced in tannins, because various hydroxyl are interacting with each other. However, it can be seen that the method of extraction of wood tannins developed in this work, presents satisfactory results.
This paper presents an anticorrosive method to protect bamboo from the corrosion induced by coating a layer of epoxy resin on the surface of bamboo slices. Four surface modifications including heat treatment, alkali treatment, coupling treatment and acetylation treatment are applied to bamboo slices. The results indicate that the ultimate tension of bamboo slices decreases when corroded in solutions with different pH for different time, while epoxy resin protects the bamboo slices from corrosion to maintain the tensile properties by coated on its surface. The surface morphology indicates that four modifications have different degrees of influence on the surface and material of bamboo slices, which can reduce the ultimate tension of bamboo slices, but improve the interfacial combination between the surface of bamboo slices and epoxy resin. Acetylation treatment was the most effective modification analysed by Fourier-transform infrared spectroscopy (FT-IR) among them.
The aim of this study has been to investigate the suitability of Pannónia poplar (Populus × euramericana cv. Pannónia) timber for structural purposes. Static and dynamic modulus of elasticity (MOE) has been determined on samples of 4 different Hungarian plantation origins. The results of the dynamic test showed the same range as the static test, showing a good correlation of the two measurements. As result it can be stated that the domestic Hungarian Pannónia poplar species have in average 11000 N.mm-2 modulus of elasticity. This exceeds considerably the threshold limit value (7000 N.mm-2) necessary for structural applications according to Eurocode 5. Therefore Pannonia poplar is suitable for structural applications, and are a good alternative of the widely used coniferous species in construction sector.
The pine stems were cut from three different polluted environments – Ist trees degradation degree (weak pollution), IInd trees degradation degree (strong pollution) and IIIrd trees degradation degree (connected with very strong pollution). On the basis of obtained results it was stated that environmental pollution caused changes in late wood participation, as well as distribution of cellulose on the stem cross- and longitudinal section. It also changed cellulose content in bark from the butt-end section, which was about 26% regardless the degradation degree. The environmental pollution caused also an increase of viscometric average polymerization degree of cellulose in heartwood in relation to heartwood adjacent sapwood and sapwood from butt-end section. Regardless the degradation degree, cellulose polymerization degree in heartwood adjacent sapwood from the middle part of the stem was higher in comparison to sapwood and heartwood. Moreover, the environmental pollution caused the increase of viscometric average polymerization degree of cellulose in bark. The polymerization degree of cellulose in bark from the butt-end section of IIIrd degradation degree stems was 22% and 23% higher in comparison to the Ist and IInd degradation degree.
To prepare hydrophobic wood with rose-like hydrophobic surface and avoid moisture damage to wood. In this paper, With polyvinyl alcohol (PVA) as the elastic mold, the microstructure of the rose petals was replicated on the wood surfaces by soft lithography. The soft lithography technique was used to modify the wood sur-face, transferring over it a rose-like topography, based on a micro/nano hierarchical structure using fresh rose as the template. The surface of poplar coated with polystyrene was reconstructed twice using 1, 3, 5, 8 and 10% PVA as templates, respectively. The results show that the average contact angle of poplar surface coated with polystyrene is more than 130°, that of fresh rose surface is about 140°, and that of untreated wood is about 60°. Therefore, the wood surface with polystyrene has obtained a similar structure to that of rose surface and has a certain hydrophobicity. In addition, the microstructures observed by means of SEM, showing rough surface structures with micro-nanopapillate hills on wood surfaces. Water droplets could easily roll down on such wood surfaces, exhibiting super-hydrophobic and low adhesion properties. The successful fabrication of rose-like wood provided a new direction for researches on the super-hydrophobic of wood, which could effectively…
The article presents results of the elimination of sticky impurities from recovered paper in laboratory flotation of three pulp suspensions with different whiteness, obtained directly from the production line before entering flotation. A combination of commercial agents releasing undesirable substances from recovered paper and means for regulation and stabilization of froth and modified micronized bentonit was used. In the flotation purification of pulp suspension with a whiteness of 53%, the combination of Prodeink Extra, Prodeink AS10 and Hydrocol OT reduced the macrostickies content by 58%, the ash content decreased from 18.5% to 4.5%, the whiteness increased from 53% to 56.4% and the residual color content was reduced from 385 ppm to 294 ppm. The pulp suspension with a whiteness of 64% showed a reduction in the content of macrostickies by 66%, a reduction in the ash content by 23.2%, an increase in whiteness by 1.4% and a reduction in the residual color content from 245 ppm to 194 ppm. The pulp suspension with a whiteness of 68.3% showed a decrease in the content of macrostickies by 58.1%, the ash content decreased from 35.7% to 6.3%, the whiteness increased by 1.1% and the content of residual color decreased from 157 ppm…
The research consisted in testing Polish sawn timber dedicated for construction applications made of pines (Pinus sylvestris L.) that grew in the Silesian Forestry Region, taking into account three parts of the log: butt, middle and top. The boards had the same cross section, a nominal thickness of 40 mm and width of 138 mm, typical for Polish structural timber. The mean nominal length of the boards under research amounted to 3500 mm. Each set was composed of 70 boards. Before the tests, boards were dried in an industrial drier until reaching the moisture content of 12%, and they were planed on 4 sides. First of all, the sawn timber was graded into strength classes, and their dynamic modulus of elasticity (MOE_dyn) was tested with a non-destructive method, with the use of a portable MTG device. The next step consisted in a bending test with four points of support, according to the EN 408 standard, and with the use of the TiraTest 2300 machine, in order to determine the global modulus of elasticity (MOE_EN-408) and the static bending strength, also referred to as modulus of rupture (MOR). Finally, the average growth ring width was determined for each board (PN-D-94021), as…
Scots pine (Pinus sylvestris L.) and Sessile oak (Quercus petraea L.) wood were thermally treated in an oven at the temperatures of 160°C, and 200°C under atmospheric pressure in the presence of air for 3 and 9 hrs. The mass loss and gross calorific value were determined. Non-treated wood samples achieved a gross calorific value of 22 193 J.g-1 for pine wood and 19 277 J.g-1 for oak wood. Whereas the calorific value of pine wood with increasing severity of treatment decreased, in the case of oak it increased. The mass loss increased with increasing treatment severity by both wood species. Mentioned differences in pine and oak wood behaviour using ATR-FTIR spectroscopy were explained. In the case of pine wood with increasing temperature and time of exposure a decrease of resin acids was observed. This may be contributed to decrease in GCV. In the case of oak wood, mainly at temperature of 200°C the degradation of hemicelluloses was observed that results in relative increasing in the lignin content with followed increase in the GCV.
Bamboo filaments were treated with boric acid and borax (the mass ratio of 1:1, the concentration of 20%) with four different treatment methods including atmospheric immersion, cold and hot bath immersion, vacuum impregnation and vacuum-pressure impregnation. The different treatment methods on the boron loading were analyzed and the corresponding flame resistance of bamboo filaments were evaluated by the cone analysis. The results showed that suitable treatment method with optimized processing indexes, such as hot and cold bath immersion in the condition of 100°C/2 h and 20°C/2 h with 3 cycles, was more credible to accelerate the percentages of boron loading in the bamboo filaments, and the lowest result was found in the samples with vacuum impregnation. Compared to the untreated samples, the heat and smoke release would be decreased significantly, especially for the samples with the promising hot and cold treatment, and promising pressure treatment, attributed to the more stable boron fixed in the bamboo filaments.
This research aimed to characterize the wood species Goiabão (Planchonella pachycarpa), following the precepts set forth in the Brazilian standard ABNT NBR 7190, as well as to evaluate the possibility of estimating physical and mechanical properties, using the analysis of variance (ANOVA) as a function of apparent density, and also to estimate the stiffness properties as a function of the respective strength property. The physical and mechanical properties were considered adequate for the use of this wood for structural purposes, being classified in class C40. According to the results of the regression models, it is possible to estimate the tensile strength parallel to the fibers as a function of the apparent density. It was also possible to estimate the longitudinal elastic modulus in the compression parallel to the fibers as a function of the compressive strength parallel to the fibers.
The porosity and pore size distribution of recent and ancient buried Phoebe zhennan are studied in this paper by means of mercury intrusion porosimetry. The results show that the micropore and mesopore diameters of recent and buried wood are mainly distributed in range of 40.3 nm and 183.1 nm respectively, while the macropore in 45276.6 nm and 3503.9 nm separately. For both samples, the pores with diameters below 349.9 nm account for about 60% of the total intrusion volume, and contribute more than 98% of the surface area. The cumulative pore area of recent wood is slightly greater and the pore diameter ranges from 50.3 nm to 349.9 nm. While the cumulative pore area of buried wood is significantly larger than and the pore diameter ranges until 50.3 nm. These results can provide information for further investigations on the sorption behaviour and the liquid permeability of ancient buried wood.
The influence of lignin content on reclaimed rubber (RR)/natural rubber (NR) blend composite properties has successfully been studied. Scanning electron microscopy (SEM) were used to understand morphology. Fourier-transform infrared spectroscopy (FTIR) for the possible chemical interaction, whereas thermogravimetric analysis (TGA) and tensile tester were used to predict strength and elongation for possible practical applications. The results indicated that the presence of lignin forms cavities which seemed to arise from complex interactions of the blend with the lignin. Those cavities dominated tensile fractured surface and the increase in lignin indicated inconsistencies of interfacial interactions. Lignin RR/NR blend composites revealed a drop in tensile strength and shift in glass transition temperature, except for the highest lignin containing blend composite. More active interactive constituent of the blend appeared to be NR. The interaction has not favored the thermal stability and crosslinking density.
In the study, part of degraded wooden components of Danxia Temple ancient architectures in China were indentified through the bright field microscope, and chemical compositions in cell walls were observed using polarized and fluorescence lights, respectively. The results showed that samples were belonged to Quercus spp., Ulmus spp., Salix spp., and Populus spp., respectively. Cellulose composition in Quercus spp. was seriously consumed by brown decay fungi, cellulose and lignin compositions in Ulmus spp. were consumed by white decay fungi under polarized and fluorescence light observations. All of these four kind of tree species themselves were easily vulnerable to be attacked by insects.
The aim of this study was to determine the 4-point bending strength and modulus of elasticity in bending of Black pine wood laminated materials reinforced with aramid fiber was bonded using epoxy or polyurethane glues separately. The samples were prepared in accordance with the TS 5497 EN 408 (2006). The results of the study determined that the highest value for static bending strength was found in the laminated wood samples (83.94 N.mm-2) that were prepared using inter-layer aramid fiber reinforced polymer (AFRP) and epoxy glue. The highest value of modulus of elasticity in bending was found in the samples prepared with inter-layer epoxy and AFRP (10311.62 N.mm-2). It was observed that the samples parallel to the glue line of the laminated material showed higher performance compared to those perpendicular to the glue line. The data obtained as a result of this study demonstrated that aramid fiber reinforced Black pine wood laminated materials can be used in the building industry as building materials.
The effect of tenon length and tenon width on withdrawal load capacity of mortise and tenon (M-T) joint was studied based on the finite element method (FEM), and the relationship of withdrawal load capacity relating to tenon length and tenon width was regressed using response surface method. The results showed that the tenon length and tenon width had remarkable effects on withdrawal load capacity of M-T joint T-shaped sample. The effect of tenon length on withdrawal load capacity was greater than tenon width. The regression equation used to predict the withdrawal load capacity was capable of optimizing the tenon sizes of M-T joint with R-square of 0.926. Using FEM can get more knowledge of M-T joint visually, and reduce the costs of materials and time of experiments.
WOOD RESEARCH Volume 66, Number 3
The effects of some polymer additives, also called super plasticizers, on selected physical and mechanical properties of cement bonded particle board were investigated. Two different kinds of poly carboxylic ether (PF300, DX40) and a melamine based polymer (300M) were added to the wood cement mixture. The ratios of polymer additives to the wood cement mixture were 1%, 1.2% and 1.4%. Cement bonded particleboards were manufactured with wood/cement (w/w) ratio of 1:3; target density of 1300 kg.m-3, and CaCl2 content of 5%. The cement bonded particleboards were tested for water absorption (2 and 24 hour), thickness swelling (2 and 24 hour), bending stiffness and strength and internal bond strength. Results of the study showed that most of the polymer addition decreased water absorption and thickness swelling of the boards. Replacement of cement with polymers increased internal bond strength and bending stiffness of the boards while bending strength was slightly reduced. Use of small amount of super plasticizers significantly improves most of the board properties.
Based on acoustic spiral metasurface, a spiral structural layer was designed to apply to timber construction interior wall. The sound absorption coefficient was measured by impedance tube method and compared with Helmholtz resonance structural layer, solid structural layer and air layer in traditional wall. The results show that the combination of the spiral structural layer and the wall can optimize the sound absorption performance of the wall in the medium and low frequency. Without reducing the overall sound-absorbing performance of the wall, can achieve perfect sound absorption in some medium and low frequency sound bands.
In this study, hydrothermal treatments (duration: 2 h, 5 h, 8 h; temperature: 60°C, 80°C, 100°C), ultrasonic treatments (duration: 60 min, 90 min, 120 min; temperature: 40°C, 50°C, 60°C; ultrasonic power: 400 W, 600 W, 800 W) and freeze-drying treatments (vacuum degree: 0.05 mbar, 0.1 mbar, 0.5 mbar, 1.0 mbar, 1.7 mbar) were performed respectively to improve the permeability of glue-laminated bamboo. The effects of different pre-treatments on the permeability were compared according to the water absorption test and the mercury intrusion porosimetry test. The microstructure change of the samples was observed by scanning electron microscope (SEM). The results showed that freeze-drying treatment was an effective way to increase the permeability of the samples, in which the water absorption rate can be increased by 47%, and the porosity can be increased by 10% at 0.5 mbar vacuum. From SEM analysis, some small holes appeared in the cell wall of the freeze-dried samples, because he free water inside the samples was changed into ice, and the volume became larger, and the pore diameter of the bamboo was enlarged.
This study aimed to evaluate the effect of oil-heat treatment on the anatomical, physical, and chemical properties of the tropical fast-growing wood species as gmelina (Gmelinaarborea) and mindi (Melia azedarach) wood. Vessel lumen area and diameter in radial and tangential direction of both species increased with increasing temperature. The fiber lumen areas in both woods were remarkably decreased by oil-heat treatment, and the fiber wall area increased considerably with increasing temperature. Both woods tended to gain weight after heat treatment at 180°C and 200°C, and then lose weight after heat treatment at 220°C. The density of mindi increased greatly at 180°C and 200°C and slightly decreased at 220°C. The dimension of the specimens in tangential direction increased with heat treatment, but the rate decreased with increasing temperature. The relative crystallinity and crystallite width of the heat-treated woods were greater than those of the untreated wood. In the Fourier transform infrared analyses, the peaks from the carbohydrates were changed after oil-heat treatment, mainly due to the degradation of hemicellulose. Consequently, it was revealed that the heat treatment affected various properties of gmelina and mindi woods. Differing characteristics between the species were also noted.
This study was carried out to determine the effects of bleaching chemicals and varnishes on the amount of carbon dioxide (CO2) in the combustion of oriental beech (Fagus orientalis Lipsky). For this purpose, samples of Oriental beech prepared according to ASTM D 358 contain 18% R1 = (NaOH + H2O2), R2 = (NaOH + Ca(OH)2 + H2O2), R3 = (Na2S2O5 + H2C2O4), R4 = (NaSiO3 + H2O2), R5 = (KMnO4 + Na2S2O5 + H2O2) solution groups, after bleaching with solution groups, water based, synthetic, polyurethane and acrylic varnish were applied according to ASTM D 3023 and combustion tests were carried out in accordance with ASTM E 160-50. Gas measurements were made with the SIGMA 74172 NSU flue gas device during the combustion process. As a result, in respect to the burning types; the highest amount of CO2 (ppm) was found in the self-combustion (8.468 ppm) while the lowest was obtained from the flame combustion source (4.599 ppm). In respect to the types of bleaching; the highest in R5 (7.458 ppm) and the lowest in R3 (4.059 ppm) were found. According to the varnish types; the highest value was found in the synthetic varnish (8.261), and the lowest value was found…
This study aims at investigating the effect of three altitude levels (below 1800 m, 1800-2000 m and above 2000 m) on the physical and biometric properties of stem-wood and branch-wood of hawthorn species. Moreover, the relationship between wood dry density and volumetric swelling, fiber length, fiber diameter, cell wall thickness were studied. Results indicated that altitude had significant effects on the dry density, volumetric swelling and fiber length of stem wood while did not significant effects on the density of branch wood. Additionally, some physical and biometric properties had relatively greater correlation coefficients in branch wood than in stem wood whereas others had higher coefficients in stem wood compared to branch wood. Deep understanding of properties this wood species will provide a fresh insight into the relationship between wood properties and environmental factors.
For use as decoration panels, wood fiber was used to prepare a new type of aromatic fiberboard using hot-press technology that mixes spices and adhesives. Experiments showed that the use of different proportions of two kinds of spices, wormwood and lavender, mixed with waterborne acrylic adhesives, had a slight influence on the curing time and viscosity of the glue. The different mixtures equally affected the physical and mechanical properties of the fiberboard and the smells similarly affected brain wave frequencies. The experimental results showed that a 20% proportion of lavender and wormwood was optimal compared with 5%, 10%, and 15%, and this amount also provided the best health-care effect. This work provides the experimental data and a theoretical basis to achieve pharmacological and health-care effects for the development of aromatic and other special kinds of fiberboard for industrial applications.
To compare the wood quality of Dahurian larch and Japanese larch growing in Korea, the physical and mechanical properties were examined using the Korean standards. The proportion of heartwood was 82% and 72% in Dahurian and Japanese larch, respectively. The percentage of latewood was 42% in Dahurian larch and 35% in Japanese larch. The growth ring width of Dahurian larch was narrower than that of Japanese larch. Dahurian larch showed about 20% higher green moisture content compare to Japanese larch wood. Density and shrinkage of Dahurian larch were higher than Japanese larch. Axial compression strength, young`s modulus in compression, and shearing strength in heartwood of Dahurian larch were 11 MPa, 686 MPa, and 2.3 MPa, respectively, showing higher value than Japanese larch. The hardness was in the range of 13.8–38.7 MPa in Dahurian larch and 17.7–48.4 MPa in Japanese larch. The compression strength parallel to the grain and shearing strength in both species were significantly correlated with oven-dried density. Besides, the hardness in Dahurian larch was significantly correlated with latewood percentage and oven-dried density. In conclusion, the differences in the properties of both species were revealed and the results can be used for quality indices of both wood species.
The purpose of this paper is to investigate the influence of kiln temperature, relative humidity and wood moisture content on the content of acid and alcohol released in the drying process of high temperature kiln by studying the radiated pine sawn timber of 40mm thickness. The drying temperature was between 101°C and 115°C, the relative humidity in the drying kiln was reduced from 86.1% to 39.6%, the moisture content of the lumber was reduced from 106.16% to 11.98%, and gas extraction was executed nine times with an extraction speed of 1.0 L•min-1 and a sampling time of 30 min. The concentrations of acids and alcohols were analyzed by HPLC. The results showed that the concentrations of formic acid, acetic acid, and methanol emitted in the kiln during drying were 215.6-748.2, 4148.8-16803.2, and 6381.9-15648.9 mg•m-3, respectively, and these concentrations were significantly higher than the relevant standards. The concentrations of the emitted formic acid and acetic acid were proportional to the drying temperature, the concentrations of the emitted formic acid and acetic acid were inversely proportional to the relative humidity in the kiln and the moisture content of the lumber. The concentration of the emitted methanol was independent of the drying temperature,…
In this work, wet-process fibreboards (hardboards) were produced in the laboratory using industrial wood fibres of the species European beech (Fagus sylvatica L.) and Turkey oak (Quercus cerris L.) at the total volume of 40%, and white poplar (Populus alba L.) at 60% volume. The effects of hot pressing pressure (varied from 3.3 MPa to 5.3 MPa) and pressing time (from 255 s to 355 s) on the physical and mechanical properties of hardboards were investigated and optimal values of the parameters for fulfilling the European standard requirements were determined. It was concluded that hardboards with acceptable physical and mechanical properties may be produced from 60% poplar wood waste and residues, combined with 40% hardwood raw materials (beech and oak) by regulating the hot pressing regime only, i.e. pressure and pressing time. The following minimum parameters for producing hardboards from mixed hardwood tree species were determined: a pressure of 4.6 MPa and a pressing time of 280 s.
The research focused in determining the lignification indicator of fresh needled springs and the mass of fresh needles in reference to the lignin content in tracheid walls of peripheral area of the stem (MFT/LC and MFN/LC) of Scots pine differentiated as far as its biosocial position within the community expressed by Kraft’s classification. The material for the analysis came from mature pine stands growing on North European Plain, on the territory of Poland. Chemical and structural analyses of wood encompassed the area of mature sapwood, i.e. thickness of the last 10 annual rings located at 1.3 m (DBH). It seems that the noticed differences values of both indicators (MFT/LC and MFN/LC) in pines belonging to the first three Kraft’s biological classes are connected with physiological, physical and structural conditionings of water transport with minerals in xylem and are closely connected with competition for sunlight, water, nutrients and living space.
The article presents the results of a marketing survey in the area of customer preferences in the case of different degrees of heat-treated solid wood and birch veneer. Part of the marketing survey was a questionnaire survey, where the respondents, as potential customers, expressed their preferences for individual samples which, at first glance, differed in colour due to the different degrees of heat treatment. The result of the research is a clear preference for the heat-treated samples compared to the reference sample without heat treatment. A more detailed secondary analysis of the data from the questionnaire survey was performed with regard to the gender, age and education of the respondents. Here, too, it is possible to conclude a clear preference for heat-treated samples for these groups of respondents. The article also analyses the possibilities of the marketing strategy with a focus on marketing communication, especially in relation to wood processors and producers.
Static load tests were carried out on three kinds of triangular girder trusses with different diameter wood dowels, and the effects of that on the structure of girder trusses were discussed. It was found that there was a good synergy between the wood dowels and the girder trusses. Among the triangular girder trusses with different diameters, the 16 mm diameters had the best energy dissipation performance increased by 184% and deformation resistance of 0.73 mm; the 20 mm diameters had the best stability performance, the better bearing capacity of 60.42 kN and deformation resistance of 0.82 mm. The bearing capacity of the double girder trusses was 2.06-2.25 times that of two single trusses, which had the ability to ‘one plus one is greater than two’.
A novel structural member, the bamboo plywood-encased thin-walled steel tube/stone dust concrete composite column (BSDCC), was investigated in this study. Axial compression tests were conducted on 10 BSDCC specimens; their failure characteristics and modes were examined, and the effects of the stone-dust concrete content ratio and strength, specimen slenderness ratio, cross-sectional composition and binding bar confinement pattern, and binding bar spacing ratio on the bearing capacity and deformation of the columns were investigated. Two main compressive failure modes were observed: (1) adhesive failure by cracking and debonding between the bamboo plywood boards and between the bamboo plywood and the steel tube and (2) compressive-flexural failure of the bamboo plywood between the binding bars in the middle of the specimen. For specimens with the same cross-sectional dimensions, the cross-sectional content ratio of the stone dust concrete impacted the deformation and failure mode but did not significantly affect the ultimate bearing capacity. The bearing capacity decreased with increasing specimen slenderness and binding bar spacing ratio and increased with increasing stone dust concrete strength and bamboo plywood constraint (in terms of the cross-sectional composition and binding bar restraint pattern). A model for the ultimate bearing capacity of BSDCCs was established through regression analysis.
The influence of addition of deinked pulps with low and high brightness to bleached eucalyptus and pine kraft pulps on functional tissue paper properties was studied. Deinked pulps with low and high brightness had some different functional properties. Deinked pulp with high brightness has higher bulk, porosity, water absorption after immersion, initial water absorption, bulk softness as well as brightness. On the contrary, the difference in relative bonded area and porosity e between deinked pulps with low and high brightness was moderate. The mixed pulps laboratory pulp sheets from bleached eucalyptus kraft pulp or bleached pine kraft pulp with addition of 20, 40 and 80% of deinked pulp with low brightness or deinked pulp with high brightness were prepared. The addition of the deinked pulp with high or low brightness to bleached kraft pulp leads to increasing of bulk, bulk softness as well as high water absorption after immersion and initial water absorption. The tensile index rapidly decreased by the addition of deinked pulps with high brightness to bleached eucalyptus and pine kraft pulps. Similarly, the addition of deinked pulp with low brightness to bleached pine kraft pulp led to rapid decreasing of tensile index. On contrary, with the addition…
WOOD RESEARCH Volume 66, Number 4
In order to explore the influence of wood’s anisotropic characteristics on Acoustic Emission (AE) signals’ propagation, the law of AE signals’ propagation velocity along different directions was studied. First, The center of the specimen’s surface was took as the AE source, then 24 directions were chose one by one every 15º around the center, and 2 AE sensors were arranged in each direction to collect the original AE signals. Second, the wavelet analysis was used to denoise the original AE signals, then the AE signals were reconstructed by Empirical Mode Decomposition (EMD). Finally, time difference location method was utilized to calculate AE signals’ propagation velocity. The results demonstrate that AE signals’ propagation velocity has obvious feature of quadratic function. In the range of 90º, as the angle of propagation direction increases, the propagation velocity of the AE signals presents a downward trend.
The aim of this work was to analyse the relationship between anatomical parameters of spruce tracheids and climatic factors and air pollution load, in the period before, during and after the maximum air pollution load. In this study we used the method of dividing annual rings into a number of equally wide sectors, for which the average values of the tracheid dimensions, i.e., the lumen area and cell wall width, were determined. This method was compared to the classic approach, which works with the average values of parameters for the entire annual ring, or for earlywood and latewood. The study showed that the trees responded to the increased concentration of pollutants by reducing the widths of the annual rings and the values of the anatomical parameters. The higher resolution of data gives us a better insight on the influence of abiotic factors to the wood structure. The ratio of cell wall thicknesses of earlywood to latewood was also shown as a good indicator of stress.
Black locust (Robinia pseudoacacia L.), beech red heartwood (Fagus sylvatica L.) and spruce (Picea abies Karst.) wood samples were treated in saturated steam at 100, 110 and 120°C then irradiated using a UV emitter mercury lamp in order to test their colour stability. Colour change was evaluated and presented in the CIE Lab colour coordinate system. Untreated black locust, beech and spruce specimens as control samples were irradiated using the same mercury lamp. Results revealed that beech produced the greatest colour stability during both steam treatment and the following UV treatment while spruce was the most sensitive species to photodegradation. Steaming reduced the colour change intensity only for black locust during photodegradation. Both redness and yellowness change demonstrate this colour stability increase. Steaming at 120°C resulted in the greatest protection against the colour alteration of black locust caused by photodegradation. The investigated thermal treatments did not change the photodegradation properties of beech and spruce specimens. A considerable increase in colour saturation of the specimens was generated by steaming, and the saturation value further increased during the UV treatment.
The cinnamaldehyde, salicylic acid, stearolic acid and citric acid were plant-derived organic compounds that can be activated to fungi, that could degrade the wood in long term. The compounds with concentrations of 3%, 5% and 7% assisted by different dispersants were impregnated into poplar (Populus nigra L.) specimens by the vacuum-pressure method. After that, weight percentage gain (WPG), decay resistance against white-rot fungi (Trametes versicolor) and brown-rot fungi (Gloeophyllum trabeum), color change, dimensional stability and mechanical properties including modulus of elasticity (MOE) and modulus of rupture (MOR) were measured. The results indicated that cinnamaldehyde impregnated poplar showed antifungi activity against both G. trabeum and T. versicolor, and citric acid impregnated poplar showed antifungi activity against G. trabeum. The color of poplar specimens before and after impregnated cinnamaldehyde and citric acid had a little change, dimensional stability had been improved and mechanical properties especially for MOR increased significantly.
This is a study of the influence of microwave (MW) pre-treatment on the permeability of Norway spruce ripewood (Picea abies L. Karst) as it affects its mechanical properties. Specimens were treated under variable moisture content, MW intensity, and impregnation processes. According to the results, the specimens with an initial moisture content of 45–65% exhibited the highest permeability values compared to reference samples. An insignificant difference was found between MW pre-treatments at 2 and 3 kW. Statistically significant results were found after long-time (24h) vacuum-pressure impregnation (LP). The average retention value following LP was 132 kg.m-3, which is almost three times greater than the MW-treated groups impregnated in a short-time vacuum-pressure process. The average depth of penetration after LP was 2.0 mm and the proportion of the impregnation area following LP was 17.6%. MW pre-treatment had no effect on the impregnability or the mechanical properties of the wood; other MW regimes are open for further examination.
The Brazilian standard ABNT 7190 (1997) establishes the strength classes C20, C30, C40 and C60 for the proper framework of the different wood types in the group of hardwoods. Associated with the strength class, which is based on the compressive strength characteristic value parallel to the fibers (fc0,k), the standard stipulates the respective values representing the stiffness (Ec0), with 19500 MPa being the reference value for the class C40, essential variables in structural design. For being the C40 class is the one with the greatest amplitude (20 MPa), it is possible that the value 19500 MPa is not the best representation of stiffness. This work aimed to verify the representativeness the stiffness value established by the Brazilian standard for C40 wood. The result obtained from the average confidence interval indicates the value of 14110 MPa as being the most representative, which may imply structures that are supposedly more rigid than they really are.
Trace element investigation and its corresponding concentration level in selected tropical woods from western Nigeria was done using PIXE-particle induced X-ray emission methods. Fifteen selected tropical woods were analyzed and twenty-seven trace elements were identified and quantified. The identified trace elements are Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Se, Br, Rb, Sr, Y, Zr, Ba, Pb and Bi. Calcium concentration were 2835, 3195, 4923, 5608, 7770, 5110, 2743, 5092 and 3451 ppm in samples 2, 5, 6, 10, 11, 12, 13, 14 and 15, respectively. Potassium recorded 2838, 4811, 3184, and 2021ppm in samples 1, 3, 8 and 9, respectively. Silicon recorded 5206 ppm for sample 4 and 5253 ppm for sample 7. Calcium and potassium were observed to have concentration level that is greater than 1000 ppm in all the studied samples, hence it can be said that calcium and potassium are major trace element of wood. The concentrations of the elements identified have no immediate health concern on environment and human, therefore the studied tropical woods safe for use as fuel and other purposes.
The purpose of this research was to analyze the performance (wear resistance, surface roughness, chip formation, and noise level) of AlCrN, TiN, and TiAlN coated tungsten carbides in cutting composite boards. The composite boards of wood plastic composite, laminated veneer lumber, and oriented strand board were cut by the coated tungsten carbide tools in a computer numerical control router. The results show that the differences in structure among the composite boards resulted in the difference in clearance wear, chip formation, surface roughness, and noise level phenomenon. The abrasive materials in wood plastic composite generated the highest clearance wear on the coated carbide tools tested. TiAlN coated carbide tool provided better wear resistance, smoother composite boards surfaces, and lower noise levels.
In this study, effects of heat treatment on bending strength, compression strength, chemical compound and solubility of Black pine wood (Pinus nigra J.F. var. seneriana) was examined. For this purpose, Black pine wood samples were kept in temperature of 250°C for 2 hours. Test results of heat-treated Black pine wood and control samples indicated that mechanical characteristics including compression strength and bending strength were affected negatively with heat treatment. Bending strength of heat treated and non-treated test samples were 129 and 76 N.mm-2, respectively. Compression strength of heat treated and non-treated test samples were 53 and 43 N.mm-2, resp. In addition, level of extractives, cellulose and hemicellulose decreased while lignin content increased with percentage of 40%. Significant decreases occurred in all chemical solubility values.
The publication is focused on the effect of ultra low and high temperature on enzymatic pretreatment of beech wood (Fagus sylvatica L.). Two fractions < 0.7 mm and 1.0 – 2.5 mm of disintegrated branches sawdust were used for experiments. Glucose and xylose yields were measured after 24, 48, and 72 hours of enzymatic hydrolysis with 15 % load of the enzyme measured to total cellulose content. The influence of freezing under -80°C and boiling under pressure at +160°C on samples before enzymatic hydrolysis was observed. Mutual combination of boiling under pressure to obtain the maximum water uptake and subsequent freezing was used to better understand the process of cell destruction. The results show that the boiling pretreatment has a positive influence on the total monosaccharide yields and the subsequent freezing may slightly increase these yields even further. The maximum monosaccharide conversion (73.24%) was achieved using the fraction < 0.7 mm.
The influence of stand density on the resin duct morphological structure and terpene components of Pinus massoniana were studied. The resin duct morphological characteristics and the relative content of the terpene components were investigated by microscopy and gas chromatography-mass spectroscopy, respectively. The experimental results revealed that there was a specific correlation between the stand density and resin duct area, resin duct diameter, and the relative contents of main terpene components in the turpentine extracts. Additionally, the relative contents of β-pinene and (+)-camphene were positively correlated with stand density, with correlation coefficients of 0.8208 and 0.5539, respectively. In contrast, the relative contents of (+)-longifolene and (+)-longicyclene were negatively correlated with stand density, with correlation coefficients of -0.5750 and -0.7726, respectively, and α-pinene, β-caryophyllene, and (+)-α-longipinene had no correlation with stand density. The relative content of (+)-α-pinene was negatively correlated with the relative contents of both (+)-longifolene and (+)-longicyclene, with correlation coefficients of -0.8770 and -0.8914, respectively. There were positive correlations between the relative contents of (+)-longifolene and (+)-longicyclene with correlation coefficient of 0.9718, (+)-longifolene and (+)-α-longipinene with correlation coefficient of 0.8399, β-caryophyllene and (+)-α-longipinene with correlation coefficient of 0.9360, and (+)-longicyclene and (+)-α-longipinene with correlation coefficient of 0.8626.
Grifola frondosa HAI 1232 was tested for ligninolytic enzyme activities and for lignin, cellulose and hemicellulose degradation during cultivation on eight common agro-forestry residues in Serbia. Wheat straw was favorable lignocellulosic for the production of Mn-dependent and Mn-independent peroxidases (2513.89 and 354.17 U L-1, respectively), while selected residues inhibited the synthesis of laccases. The highest lignin removal was observed during fermentation of blackberry sawdust (36.75%), while the highest selectivity index was recorded on oak sawdust (4.34). The dry matter loss varied between 8.17% in corn stalks and 14.16% in apple sawdust. According to the presented results, it can be concluded that G. frondosa HAI 1232 could be an important participant in various biotechnological processes due to its high capacity to selectively degrade different agro-forestry residues.
Four solvents including distilled water, acetone, ethyl acetate and petroleum ether were used to extract xylem of C. camphora. The differences in chemical compounds of xylem of C. camphora were analyzed by gas chromatography/mass spectrometry (GC/MS) and the anti-fungal activity of C. camphora extractives on Coriolus versicolor (CV), Trametes versicolor (TV), Poria vaporaria (PP) and Gloeophyllum trabeum (GT) were tested. The result showed that the chemical composition and relative content of the four different solvent extracts were different. A large number of chemical compounds in the C. camphora extractives had a variety of biological activity and certain application value. The growth inhibitory rates of ethyl acetate extracts of C. camphora on PP, CV, TV and GT were 52.24%, 52.51%, 43.26%, and 54.63%, respectively. According to the concentration for 50% of maximal effect, the inhibitory order on test fungus were GT > PP > CV > TV.
Given the carcinogenicity of hardwood dust, the aim of this study was to determine the effectiveness of the photometric method for different types of woodworking machines and its application in determining the mass concentration of inhalable dust for raw and dry hardwoods. In addition to the optical part of the device, the input part of the measuring device contains the Institute of Occupational Medicine (IOM) inhalable dust filter holder. This correlation of gravimetric and photometric methods in determining the dust mass concentration showed that photometry underestimates the mass concentration measured gravimetrically. The results of this study recommend the application of a correction factor 2 for a timber band saw and a correction factor 3 for circular saws in determining the mass concentration of hardwood dust by the photometric method. It was showed that photometry can be used if the correction factor of the optical device has been previously tested for specific wood processing place.
The paper aims to use the residue of sunflower seed hulls to obtain organic briquettes and to improve their properties by using larch shavings obtained in the process of solid wood planning. The physical-mechanical properties of briquettes made on a hydraulic machine, calorific value, ash content and volatile content were evaluated. The obtain results highlighted the briquettes obtained from larch waste, but also the acceptable characteristics of the briquettes obtained from sunflower seed husks. The main conclusions of this study is that briquettes obtained from unprocessed sunflower seed husks are acceptable in terms of physical-mechanical and calorific characteristics, even if they do not reach the level of briquettes obtained from larch shavings.
WOOD RESEARCH Volume 66, Number 5
The correspondence of natural and laboratory-accelerated aging of WPC has long been a highly important problem discussed by many scholars. In this work, the changes in moisture content (MC), modulus of rupture (MOR), modulus of elasticity (MOE), screw holding force and creep recovery rates of two groups of wood-plastic composites (WPC) after natural and accelerated aging (high-low temperature cycles and freeze-thaw cycles) were studied to provide guidance for the use of WPC in outdoor applications. The results showed that, after the natural aging and freeze-thaw cycles treatments, MC increased significantly with both 167% of the untreated value of wood-HDPE composites with 30% wood fiber content and a thickness of 25 mm (W25), while 67% and 133% of the wood-HDPE composites with 30% wood fiber content and a thickness of 20 mm (W20), but is almost unchanged after the treatment with high-low temperature cycles. The mechanical strength, including MOR, MOE, screw holding force and creep recovery rate, decreased after natural and accelerated aging. The greatest decreases of MOR, MOE, screw holding force and creep recovery rate were 14%, 13%, 21%, and 7% for W25, while 5%, 8%, 8%, and 14% for W20 respectively. Environmental aging can reduce the strength of WPC,…
The Brazilian standard ABNT NBR 7190 (1997) governs the premises for the wood structure sizing through a table and the simplified method. Thus, this research aims to analyze whether the simplified method shown in the standard matches the resistance values of 72 Brazilian species, separated from class C20 to C60. In the end, it was possible to conclude that the value displayed by the standard between the ratio of shear and compression in the direction parallel to the fibers is half of what actually happens in Brazilian species, showing an urgent review in the standard premises.
In order to improve the permeability of Cunninghamia lanceolata, the weight gain rate of C. lanceolata was taken as index. The effect of time, temperature and water content on the weight gain rate of impregnated wood was analyzed by frozen and steaming treatment. By comparing the weight gain rate under different modification methods, the optimal modification process was determined. The results indicate that the optimum parameters of C. lanceolata were saturated water content (-25°C and 8 h) at this time, the three-day gain rate of silica sol impregnated at normal temperature and pressure was 15.058%. After C. lanceolata is pre-treated by superheated steam, the weight gain rate of C. lanceolata, which in oven-dried specimen (120°C and 3 h) contents was the highest, at this time, the three-day gain rate of silica sol impregnated at normal temperature and pressure was 15.291%. By comparing the results of pre-freezing with the results of superheated steam treatment of C. lanceolata, the latter will increase the permeability of C. lanceolata better. Therefore superheated steam treatment should be chosen as an effective method for the pretreatment.
This study is aimed to investigate of an impact of electrical cables installed on Norway spruce (Picea abies (L.) Karst.) wood board surface on main ignition parameters (mainly critical heat flux, ignition temperature, thermal response parameter and thermal inertia). Ignition parameters have been determined by dependence of ignition times (raised to the power of -1, -1/2 and -0.547) on heat flux. Initiation times have been measured for three configurations of spruce wood boards with surface dimensions of 100 x 100 mm ± 1 mm (the first configuration: board without cables on surface, the second configuration: board with three electrical cables on surface - spacing between cables was equal to their diameter and the third configuration: board with five electrical cables - spacing between cables was equal to their diameter) at five heat fluxes (30, 35, 40, 45 and 50 kW·m-2). Obtained results proved that installation of the electrical cables on the spruce wood board surface has a significant impact on the ignition parameters. The critical heat flux (8.5 kW·m-2), apparent thermal inertia 0.20 ± 0.02 kJ2·m-4·K-2·s-1 and ignition temperature 324 ± 105°C of spruce wood board increased up to 18 ± 3 kW·m-2 (critical heat flux), 0.68 ± 0.03 kJ2·m-4·K-2·s-1…
Four coniferous and four deciduous commercial tree species from Northeastern of China were selected to investigate the differences of metabolites in wood-forming tissues by gas chromatography-mass spectrometry. The results showed that the identified metabolites mainly consisted of neutral sugars, lipids, and organic acids. The mean contents of both arabinofuranose and 1-cyclohexene-1-carboxylic acid were higher in coniferous trees than in deciduous ones. Similarly, the D-fructose and D-glucose content was significantly higher in coniferous trees than deciduous trees, but the total contents of these two sugars was roughly equal among most tree species. The mean content of lactic acid, glycerol and malic acid was lower in coniferous trees than deciduous trees. The malic acid content decreased in later-stages of wood formation than in early-stage for all tree species. The content of L-proline and myo-inositol was greater in later-stage of wood formation than early-stage. The content of octadecanoic acid, D-fructose and D-glucose decreased in later-stage of wood formation for most tree species. All of this suggested that the metabolites in wood-forming tissues showed the significance of species-specific and seasonal dynamic differences among the eight tree species.
The aim of this study was to investigate the effect of impregnating materials (low molecular weight phenol formaldehyde or LmwPF and succinic anhydride or SA), their concentrations (5 and 10%), and compression ratios (20 and 40% from initial thickness) on improvement of specific gravity (SG) and dimensional stability on nyatoh, sepetir, and pisang putih wood; and then compared them to control and densified wood. The results showed that SG and dimensional stability of compregnated wood were affected by all parameters studied. Higher compression ratio and concentration will result in a greater improvement. In general, SG and dimensional stability of compregnated wood were better than the control. SG of LmwPF- and SA-compregnated wood increased by 10.69‒22.31% and 6.96‒23.09%, respectively. Utilization of LmwPF and SA has significantly reduced the spring-back, but the latter is better. The compression-set recovery after compregnation was 18.34‒33.99%, while after densification was 47.86‒71.49%.
In this work, linseed oil was impregnated into the wood at room temperature, under vacuum pressure. The properties of linseed oil-treated wood, including dimensional stability, wood moisture absorption, chemical structure, thermostability, and morphological characteristics, were evaluated. Linseed oil displayed good permeability in Ailanthus wood, with weight gains of 30.95% after impregnation. The swelling coefficients of treated wood in the tangential and radial directions decreased by 25.97 to 33.33%, indicating that impregnation improved the dimensional stability of wood. Moreover, linseed oil treatment significantly modified the wood structure, although the FTIR spectra generally remained unchanged. Observation by scanning electron microscopy showed, that linseed oil impregnated into the wood and occluded pits, thereby prevented moisture absorption. This technique can be used in a variety of wood products, such as buildings, furniture, and landscape architecture.
In order to improve the power selection of the drive unit for the shredding machines, the authors determine the values of friction coefficients used in the cutting force models. These values consider the friction between steel and such wood-based materials as chipboard, MDF and OSB. The tests concern laminated and non-laminated external surfaces and surfaces subjected to cutting processes. The value of the coefficient of friction for the tested materials is in the range: for the static coefficient of friction 0.77-0.33, and for the kinetic coefficient of friction 0.68-0.25. The highest values of the static and kinematic coefficient of friction were recorded for MDF (non-laminated external surface) and they were equal respectively: 0.77 and 0.68. In turn, the smallest values of the discussed coefficients were recorded for chipboard (laminated external wood-base surface), which were at the level of 0.33 and 0.25, resp.
In this paper, non-linear finite elements models (FEM) of steel-timber composite (STC) beams have been developed and analyzed using ABAQUS software. In the FEM, the loading conditions of STC beams were simulated, and the nonlinear behaviour of the contact interface between the steel and timber components were incorporated adequately into the FEM. For the yield load, the maximum error between the FE results and the experimental results is 14.85%. The maximum average error of the yield deflection is 12.94%. and of the ultimate load is 16.79%. However, the error of key points was less than 17% (within a reasonable range), which proves that the established finite element model, selected material parameters and contact element model can better simulate the bending performance of STC beams. Finally, a parametric study was carried out by using the verified FEM. It is shown that the FEM developed in this study can replicate adequately the load-deflection response, and the development of stress and plasticity of the bending experiment. Through the parameter study, it can be seen that the distribution density and mechanical properties of the connection between the glulam and H-section steel can affect the mechanical behavior of the whole STC beams.
The study presents theoretical aspects and modern technologies for processing wood biomass, considers the possibility of obtaining wood chips from felling residues of cutting areas, in particular technological chips that meet the GOST 15815: 1983 “Technological chips. Specifications" standard for use as raw materials in the production of fiberboard. Wood fiber obtained from similar in size and quality indicators according to GOST 15815: 1983 technological chips, pre-treated in a defibrator, was subjected to a refining process at a low concentration, in particular using the developed design of the disks of the refiner of fibrillating action while regulating the main parameters of the process. The resulting wood-fiber mass was characterized by an improvement in the fractional composition of fibers, their size and quality indicators. As a result, improving the quality of the wood-fiber mass provides an increase in the physical and mechanical properties of wood-fiber boards under all other equal production conditions, which excludes the use of binding resins, and may indicate the possibilit of effective processing of logging waste.
Thick-walled ray cells of Haloxylon ammodendron were first reported by Zhou and Gong in 2017, but their formation mechanism remains unknown. In this study, we performed a proteomic analysis of ray cell wall formation in the xylem. H. ammodendron in Shihezi exhibits a thicker ray cell wall than that in Jinghe. During the process of cell wall biosynthesis in the xylem of H. ammodendron, the nonspecific lipid-transfer protein and beta expansin EXPB2.1 (Mirabilis jalapa) first loosen the cell wall, and this step is followed by extension and expansion. Subsequently, xyloglucan endotransglycosylase/hydrolase 1 cleaves and links the xyloglucan chains. Photosystem I P700 apoprotein A1, reversibly glycosylated polypeptide 1 and GDP-mannose-3′,5′-epimerase are involved in the cellulose, hemicellulose and pectin biosynthesis processes in the cell wall by providing components or energy. Finally, the proteins involved in phenylpropanoid biosynthesis promote lignification of the ray cell wall and complete the biosynthetic process of the cell wall.
To exploit the spruce-pine-fir (SPF) panel and the parallel strand bamboo (PSB) panel used in light wood framed shear wall and investigate the lateral behaviors of frame-to-sheathing joints in light wood framed shear wall with different characteristics, the experimental investigation and reliability analysis were carried out under monotonic load. The test configurations included joints with perpendicular-to-framing-grain load or parallel-to-framing-grain load, with SPF sheathing panel or PSB sheathing panel and with nail or screw. The results suggested that nailed joints with PSB panel occurred ductile failure but other joints occurred brittle failure. Moreover, the ultimate bearing capacity and the elastic stiffness of the joints under perpendicular load were higher than that of the joints under parallel load. The use of PSB panel and screw increased the ultimate bearing capacity of the joints. Furthermore, based on Johansen yield theory and experimental results, the reliability analysis was carried out through first-order reliability methods. The results showed that the SPF-nail joints, the PSB-nail joints, and PSB-screw joints achieved the reliability requirements.
This study aims to compare and evaluate the international competitiveness of the furniture industry in the selected European Union (EU) countries using chosen result-oriented indicators. The results found that countries with the highest levels of international competitiveness of the furniture industry included Poland, Romania and Italy. In contrast, the comparative advantage of Germany, which is the largest furniture exporter in the EU, was not as significant. No comparative advantage in the furniture trade was observed in France and United Kingdom, which is confirmed by the negative values of the Relative Trade Advantage (RTA) index and by unfavorable values of the export specialization index. The results presented in the article expand the existing knowledge in the area of assessing the international competitiveness of the largest furniture exporters.
A sandwich panel with a high ratio of strength to weight is commonly used in aerospace, construction, packaging and other fields. Using a renewable material such as wood to make sandwich panels can achieve a perfect unity of material and structure. In view of the lack of systematic analyses of wood-based sandwich panels, this work reviewed the development of wood-based sandwich panels. Based on the core structure, these panels can be divided into hollow-core structures and solid-core structures. With the emergence of new materials and new technologies, new wood-based sandwich products had been created. However, the current research only focused on the manufacturing, and the related novel design was still lacking. This work put forward a research idea of bionic design based on the integration of structure and function and pointed out the research direction for wood-based sandwich panels.
The addition of inorganic filler material in medium density fiberboard (MDF) and the effect on material properties as a function of particle size was examined. Medium density fiberboard was manufactured in a laboratory scale environment to a target raw density of 750 kgm-3. Wood fibers were replaced by using calcium carbonate at 3 and 10 wt.% using fillers with weighted median particle sizes of d50 = 2.0 μm and d50 = 30 μm, respectively. Urea formaldehyde resin was used as binder in all MDF. The influence of filler addition on the modulus of elasticity, bending and tensile strength, dimensional stability and liquid permeability was investigated. The results demonstrate the effect of filler content and its dependence on particle size. The addition of filler with d50 = 30 μm does not have any influence on material properties up to a filler content of 10 wt.%. Using the finer filler with d50 = 2.0 μm at 10 wt.% filler, the quantity significantly increases the water adsorption and swelling behavior and reduces the strength properties of the MDF.
WOOD RESEARCH Volume 66, Number 6
The article deals with durability of wood, durability of wooden structures and surface modification of wood. We are trying to eliminate the factors causing degradation of wood with the use of photocatalytic materials. Those materials are efficient UV absorbers and they are able to destroy biological aggressors also. The planar particles of titanium oxide TiO2 were chosen for the purpose of our research and applied on a wooden surface. In our case, we used a water solution of TiO2. The main goal of our work was to study the interaction between planar particles of TiO2 and wood matter. The samples of pine wood (Pinus sylvestris) were monitored for 255 days and subsequently evaluated using an electron microscope. The use of TiO2 was compared with reference material and a reference commercial coating.
The goal of this research is to investigate some morphological (fibre length, fibre diameter, cell wall thickness, Runkel coefficient, flexibility coefficient, slenderness coefficient, rigidity coefficient, Luce's coefficient, solid coefficient), physical (dry wood density, volumetric shrinkage) and chemical (cellulose, hemicellulose, lignin, ash and acetone soluble extractives contents) composition of Konar (Ziziphus spina-christi) wood grown in Hormozgan province, Iran. For this purpose, three normal trees were selected randomly and a disk was cut from each one at breast height. Anatomical inspection revealed that the species was diffuse porous, with distinctive growth rings, simple preformation plate, with polygonal openings, and banded or diffuse-in aggregates parenchyma. The average values of wood dry density, fiber length, fiber diameter, cell wall thickness, Runkel coefficient, flexibility coefficient, felting coefficient, Luce’s coefficient, solid coefficient, rigidity coefficient were 0.926, 52.1, 77.85, 0.57, 163 ×103 μ3 and 0.48. Cellulose, hemicellulose, lignin, acetone soluble, extractives, ash contents were 43.34, 19.98, 33.9, 6.42 and 2.78%, resp.
The subject of this paper is an experimental and numerical analysis of the stability of the wall panels with one-side board sheathing for timber structures. The reinforcement of the panel is provided using glued timber composite I-shaped element consisting of a web made of a wood-based desk embedded into flanges of solid timber. The mechanism of the behaviour of these panels, mode of the failure and reliable procedure to determine the buckling load-bearing capacity not been fully explored so far. This work describes the behaviour of the wall panel under vertical load and the method of failure using experimental and numerical analysis. The reduction coefficient kJ was determined, which can be used for a simple calculation of the buckling capacity of a wall panel.
A high-efficiency fire retardant composition was prepared with dicyandiamide, phosphoric acid, boric acid, borax, urea and magnesium sulfate and it was used to process veneers which were then to prepare the plywood. Meanwhile, heat release and smoke release from combustion of plywood were tested by a cone calorimeter, including heat release rate, mass loss rate, CO yield, CO2 yield and oxygen consumption. Results showed that the plywood with this fire retardant treatment had the better flame-retardant performance and smoke suppression effect as well as the stronger char-forming capability compared to plywood without fire retardant treatment. The average heat release rate, total heat release, average effective heat of combustion, total smoke release, CO yield and oxygen consumption of the plywood with fire retardant treatment were decreased by 63.72%, 91.94%, 53.70%, 76.81%, 84.99% and 91.86%, respectively. Moreover, the fire growth index of plywood treated by fire retardant was relatively low (3.454 kW·m-2·s-1) and it took longer time to reach the peak heat release rate, accompanied with slow fire spreading. The fire performance index was relatively high (0.136 s·m2·kW-1) and it took longer time to be ignited, thus leaving a long time for escaping at fire accidents. The fire hazard of plywood with…
This paper compares two concepts of composite timber concrete ceilings and their uncoupled alternatives based on a parametric study by comparing the final deflections of individual variants and at the same time considering according to the ultimate limit state. It includes a comparison of coupled and uncoupled variants while maintaining the same boundary conditions as the load, the thickness of the ceiling structure and the load width. By considering other factors, we can achieve more optimal variant, thanks to more accurate consideration of the required boundary conditions such as the complexity of installation or fire resistance. The purpose of this paper is to simplify the optimal selection of the ceiling structure based on the suitability of the supporting structure.
This study examined the properties of components connected by beech and self-tapping screw composite dowels (group C). As a contrast, the components connected by beech dowels and self-tapping screws individually were tested. The test results indicated that the properties of the components connected by beech dowels (group B) were better than those connected by self-tapping screws (group S), except the ductility coefficient, final displacement, and energy consumption. On the other hand, the main failure modes of groups B and S were the broken beech dowel and the bent self-tapping screw, respectively. For group C, two peak values could be found which were larger than the maximum load of groups B and S, respectively. The properties of group C were better than those of groups B and S, except that the final displacement and energy consumption were located between those of groups B and S. Meanwhile, the linear equation in two unknowns have be found between groups B, S and C.
This paper presents a series of full-scale tests conducted with office furniture made from OSB boards. Ignition source (30 kW gas burner) position and enclosure effects, free burn vs. ISO 9705 room, were evaluated from the perspective of instantaneous (HRR) and total heat (THR) released by the fuel packages. It was found that both of the evaluated factors have impact primarily on HRR – the peak ranging from 874 kW to 1 154 kW was delayed by approx. 50 to 60 s in the free-burn experiments; the THR remained relatively consistent at approx. 875 ± 30 MJ, meaning that in the observed period very similar amounts of fuel were burned. The thermal feedback within the enclosure seemed to be partially counteracted by the lack of oxygen, resulting in slightly higher HRR in free-burn test following the first peak. The findings of the research are applicable to fire hazard prediction by fire modelling.
The effects of edge distances on stiffness in glulam connections with inclined selftapping screws were studied in this paper. Under four anchorage angles (A-45°, A-60°, A-75°, A-90°) and three edge distances (EG-2D, EG-4D, EG-6D) conditions, the shear-tension tests were carried out on the timber structure connections with inclined self-tapping screws, and the stiffness and other properties of the connections were tested. Based on the results, the effects of edge distances on stiffness in joints were quantified using the equivalent energy elastic-plastic (EEEP) model. The results showed that the edge distances had a certain impact on the yield mode and load-carrying performance of the joints. Within a certain range of variation, as the edge distance increased, the stiffness of the connections increased gradually, showing a positive correlation. The stiffness of specimen EG-2D is 4.41 kN·mm-1. The stiffness of specimen EG-4D is 10.04 kN·mm-1, which increases by 128% compared with the specimen EG-2D. The stiffness of specimen EG-6D is 12.08 kN·mm-1, which increases by 174% compared with the specimen EG-2D. However, the ductility coefficient, yielding load, and energy dissipating have no significant change. Within a reasonable edge distance, only ductile damage occurred.
The aim of this study was to determine basic anatomical features of annual plant fibers used as wood substitutes for the production of wood-based panels. For this purpose rye, wheat, triticale, rape and corn straw were used. The determination of the morphological features of the fibers was conducted on the macerated material. Fiber lengths, fiber diameters and lumens were measured, and then the fiber wall thicknesses and slenderness ratios were calculated. The result clearly showed significant differences among all fiber characteristics of the tested plants. The strength and direction of the relationship between the anatomical properties determined in the study and the physicomechanical properties of the boards produced with straw from the tested annual plants were identified.
In this article, the dynamic parameters (frequencies, mode shapes, damping ratios) of the uncoated wooden shed and the coated by silicon dioxide are compared using the operational modal analysis method. Ambient excitation was provided from micro tremor ambient vibration data on ground level. Enhanced frequency domain decomposition (EFDD) was used for output. Very best correlation was found between mode shapes. Nano-SiO2 gel applied to the entire outer surface of the red oak shed has an average of 14.54% difference in frequency values and 13.53% in damping ratios, proving that nanomaterials can be used to increase internal rigidity in wooden slabs. High adherence of silicon dioxide to wooden surfaces was observed as another important result of this study.
Formaldehyde emission still remains a major disadvantage of widely applied formaldehyde-containing amino resins such as UF (urea-formaldehyde) resin and MUF (melamine-urea-formaldehyde) resin. The compositions of adhesives for plywood manufacturing have to contain a proper extenders in order to adjust their viscosity. Thus, the aim of the study was to investigate the effect of protein-rich soy flour (SF) as the extender for adhesives. The composition of flours and their ability to absorb the formaldehyde were determined. Properties of liquid resins such as gel time, viscosity, pH and solid content were investigated. The possible chemical interaction between the extenders and resins were assessed with the use of FTIR spectroscopy. Plywood panels manufactured using UF and MUF adhesives with the soy flour introduced as the extender in various concentrations were tested in terms of shear strength and formaldehyde release. Studies have shown that soy flour has a favorable composition and formaldehyde-scavenging ability. The addition of SF affected resins properties such as viscosity and gel time but showed no influence on their pH and solid content. FTIR analysis has not explained the chemical interaction between resin and extender. The application of soy flour in the concentration of 15% for UF resin and 10% for…
This paper deals with the effect of saw blade type (24, 40 and 60 teeth) and sawn distance on the primary profile (Pz) of tranvesre surface of European oak (Quercus robur L.) after transversal cutting. Transversal cutting was provided at constant cutting speed vc = 62 m.s-1 and with manual feeding using circular saw blade. An additional parameter was to determine the maximum sawn distance for each type of saw blade up to the point where the saw blade overheated, as well as the beginning of the blackening of the wood surface. The highest values of the primary profile (Pz) were achieved with a saw blade with 24 teeth, lower values were measured on wood cut with a 40 tooth blade and the lowest values after cutting with a 60 tooth blade. As the saw distance increased, there was no rapid and steep increase in the primary profile values, but these values gradually increased slightly, probably due to the gradual blunting of the tool.
In this study, three samples taken from the planks of the Yenikapı 29 shipwreck were analysed. Firstly, the maximum water content (MWC) and basic density values of the samples were calculated. MWC of the IK13-1 was 164% and the MWC of the SK6-1 was 87%. Because of these low MWC values, samples could be classified as non-degraded. When the SEM images of these two samples were examined, it was understood that the IK13-1 sample was non-degraded but the SK6-1 sample was penetrated with corrosion product and could not be classified as non-degraded. With these analyses, the XRF method was used to measure the iron amounts of the samples. The iron amount of the SK6-1 was 32.3% and the corrosion accumulation in this sample was also proved with XRF. In order to avoid incorrect results, multiple analysis techniques should be used for determining the physical condition of the waterlogged wood near the corroded parts.
CAD software and FEM analysis were used to modify the drum of threshing machine into machine for chopping wood residues. The operating parameters that affecting the performance of the chopping machine are drum speed (450, 1000 and 1200 rpm), three stages of serrated disk arrangement clearance between drum flail knives (0.7, 1.5 and 3 cm) and three levels of feeding capacity (W1 300, W2 = 360 and W3 = 420 kg.h-1). The developed machine was operated by the addition of two types of knives (sharp free knives + serrated discs) to the original knife existing already in the machine. The machine was evaluated in terms of production capacity, cutting efficiency, power requirements and energy consumption. Using the modified (serrated) saw disk mill and flail knives reduced the energy requirement for chopping and raised fine degree of the chopped materials and solve the clogging problem. The cutting productivity and cutting efficiency raised with reducing the clearance between flail knives (0.7, 1.5 and 3 cm) while the power requirements and energy consumption reduced.
This study focuses on trade of hardwood products in selected countries of Eastern Europe, specifically the Czech Republic, Slovakia, and Hungary. It was supported by a survey conducted with companies producing products made of hardwoods. It monitors trade trends in the wood products industry, specifically focusing on lumber, wooden veneers, furniture production, musical instruments, and wooden accessories. It also addresses the current and potential import and use of the US hardwood lumber in these countries. The study is also pointing out the shortcomings of the monitored markets. The online questionnaire and follow-up phone calls were used to obtain information from companies in countries of interest. Results showed that 83.3% of Czech respondents already use imported hardwoods in their production, followed by Hungary (69.2%) and Slovakia (54.6%). Despite the relatively high values of imported hardwood products, the overall results show that there is only a small potential for an increase in import of the US hardwoods in the wood products industry in chosen countries. The utilization of tropical hardwood species will continue because of their superior properties for specialized products such as musical instruments. Results also point out the grooving importance of certified hardwoods, their utilization, and trade.
Volume 65 (2020)
WOOD RESEARCH Volume 65, Number 1
There are often many scars and hollows in ancient and famous trees. As a convenient and effective non-destructive testing tool, ground-penetrating (GPR) has a technical advantage in detecting abnormality in trees. But the tree radar images always inherit some extent of noise in them. Thus, denoising is very important to extract useful information from a tree radar image. Shearlet is a directional multi-scale framework, which has been shown effective to identify sparse anisotropic edges even in the presence of a large quantity of noise. This article presents an efficient denoising method based on shearlet applied on the tree radar images. Experimental results on forward modeling and standing trees radar data substantiate that the proposed method has the best denoising performance, especially in preserving the edge information as compared with the other methods which are based on wavelet, curvelet and contourlet.
The paper deals with length of tracheids of bald cypress at two alluvial sites in Serbia. Scope of the paper was to establish site inf luence (climate, soil, etc.) on mentioned anatomical feature and to quantify it, as well. Axial tracheid changes have been observed depending on three factors: cambial age, zone inside growth ring and stem height where sampling was performed. The paper established gradually increasing of axial tracheid length with cambial age and that did not depend on zone inside growth ring and stem height. There was also significant inf luence of the zone inside growth ring to axial tracheid length, while stem height where sampling was performed does not have significant inf luence. There was found relation between factors that determine site such as physical and chemical soil properties and climate from one and axial tracheid length from another side.
Conventional papers are not suitable for printed electronics because they have a rougher surface than the plastic film commonly used for electronics printing. The paper surfaces were modified by coating and calendering processes to reduce surface roughness and electrical resistance of inkjet-printed UHF RFID antennas. The composition of coatings, the main component which included aluminum oxide pigment, had an influence on the surface roughness, the surface pore content and the electrical resistance of the inkjet-printed UHF RFID antennas on coated papers. Papers coated with a mixture containing 25% polyvinyl alcohol binder in combination with the cationic polymer PDADMAC without glyoxal crosslinker had the lowest surface roughnesses and the lowest electrical resistances of the inkjet-printed antennas. As the coating basis weight increased, the electrical resistance of the antennas increased. Reduction of the electrical resistance of the antennas was achieved after calendering coated paper. The design of the antennas had a significant effect on their electrical resistance, which increased with the length of the antenna.
Bionic bamboo element is innovative form inspired by honeycomb, and its axial compressive strength and node’s contribution to strength under different environment were studied to explore the mechanical properties. Crack morphology and stress distribution were analyzed. The results indicated that, the strength of bionic bamboo element was 50.72 MPa, while the strength declined by 39.74%, 43.85% and 36.05% after being immersed in water for 30 days and hygrothermal pretreatment for 30 days and 15 days. Node had negative influence on strength due to fiber hydroscopic swelling and loose compared with the control samples, and lower humidity condition was beneficial to enhance the compressive strength, e.g. the strength of samples in humidity 20% condition for 30 days improved by 56.70% compared with the control group. Crack showed hierarchical damage with fibers’ tear in length and fracture in lateral, stress distribution exhibited symmetry, and the maximum stress focused on the end of bionic bamboo element, and its thin wall was susceptible damaged. Bionic bamboo element retained the mechanical superiority of bamboo culm and promoted its recombination utilization.
The aim of the present review is to summarize the current state of research in the field of sustainable bio-based adhesives used for production of eco-friendly wood composite materials. The article is focused mainly on the use of lignin, starch and tannins as raw materials and alternatives to the existing conventional adhesives. It is expected that increased amounts of bio-based adhesives will be used in the production of wood composites in order to meet the current needs for development of sustainable and innovative materials which will make the wood-based panel industry more sustainable and lower its dependence on fossil fuels. However, there are still substantial challenges for the complete replacement of petroleum-based wood adhesives with bio-based adhesives, mainly because of their relatively poor water resistance, low bonding strength and large natural variations due to different growing conditions. In this respect, fundamental research is still need in order to determine the factors for formulating bio-based adhesives with optimal properties and broaden their application in wood-based panel industry.
The acoustic simulations were carried out for softwood and composites in order to evaluate their sound properties. Theoretical value of sound insulation was predicted by regarding the substances in the wood cell wall as equivalence to specific medium based on Biot model, and the wood microscopic characteristics, such as the length and diameter of tracheid, diameter of pit, and porosity, were taken into account for determining the equivalent density and bulk modulus of wood. By comparing the tested and predicted values of sound insulation, the conclusions were drawn as follows: the predicted values of sound insulation were significantly correlated with the tested values for wood and wood composites. As for Masson pine, the adjacent of earlywood and latewood was considered as sandwich structure for the calculation of sound insulation. The transfer function involved in sound insulation simulation provided an effective method to characterize the sound insulation volume of wood and wood composite in construction and decoration areas.
This work presents the results of selected wood properties in birch trees grown on a provenance experiment plot established as a seed orchard. The study concerned: basic density, oven-dry density and compression strength along the grain at a moisture content of 0% and at moisture content above fiber saturation point. Analyses were performed on 971 wood samples collected from 28 trees at the level of breast height. It was found high variability for diameter of breast height (22%) and relatively low for basic density (9%) and oven-dry density (11%). Average basic density was 446.5 kg.m-3 and average oven-dry density was 537.9 kg.m-3. The compression strength at 0% moisture content was four times higher (65 MPa) than the strength at moisture content above the fiber saturation point (16.6 MPa). Most of clones had similar properties within the limits of statistical errors, but a few clones exhibited statistically significant low value.
In this study, it was aimed to investigate the effects of weathering on some surface characteristics such as color and surface roughness changes of Scots pine impregnated with copper-containing chemical such as Wolmanit CX-8 (WCX-8) and varnished with synthetic varnish (SV), cellulosic varnish (CV), and polyurethane varnish (PV) were investigated. Results showed that while the WCX-8 impregnated and PV coated Scots pine specimens showed better color stability than other treatment groups after weathering, only CV coated Scots pine gave the most negative effect on color stability. While, the untreated (control) wood surface turned from red to green and yellow to blue respectively, after weathering, other all treatment groups gave reddish and yellowish tone after weathering. Weathering conditions increased the surface roughness of control (untreated) and other all treatment groups. The control group gave a rougher surface than other treatment groups after weathering. Surface roughness increases were the lower for CV coated Scots pine wood than other treatment groups. The results showed that while WCX-8 impregnation before varnishing gave better color characteristics, generally it caused to increase the surface roughness of Scots pine after weathering.
Analysis of modulus of elasticity of spruce beams under bending with and without fibre reinforcement
The modulus of elasticity has been assumed constant during the finite element (FE) analysis of CFRP reinforced real sized timbers analyzed in load test in laboratory. The latest investigations have shown that it varies significantly during the loading process. Analysis of the modulus of elasticity during the loading provides answers to several questions, by which the FE analysis can be profoundly optimized and yield more accurate estimates. Analysis has been extended to load-modulus functions of previous investigations. Specimens without reinforcement were also included in the investigations, in order to eliminate anomalies of previous measurements and to get easier comparison.
The paper investigates the possibility of producing the water-resistant plywood of increased elasticity with use of veneers attained from European wood species, such as alder, birch, beech, pine as well as linden, poplar, willow and spruce. Plywood was produced in two variants. Variant I of plywood was made from various wood species, yet the veneers were of the same thickness. In variant II the centre layer in each case was made from 1 mm thick pine veneer and the face layers were made from 1.4 mm thick veneers of various wood species. The produced plywood was subjected to tests on modulus of rupture, modulus of elasticity and tensile strength, bond quality and compression ratio. Specific values of modulus of rupture and modulus of elasticity were also determined taking into consideration the differences in the thickness of applied veneers. Based on these investigations, the authors concluded that, regardless of the manufacturing method, the highest values of modulus of rupture as well as modulus of elasticity and bond quality are achieved for plywood made from linden, poplar, willow and spruce. The change in the plywood structure (variant II) resulted in a considerable decrease in the values of modulus of rupture and modulus…
Effect of face layer manipulation on the density profile and properties of low density particleboard
Density reduction has gradually become a trend for the particleboard and furniture industries due to increased price and insufficient supply of wood. However, reduced density of the panels by the simple reduction of the wood material comes along with deterioration of the properties. In this study, to achieve sufficient properties (bending properties in particular), the particle moisture content (MC) and geometry in face layers were manipulated to manufacture low density particleboards (500 kg.m-3), with the core layer composed of a mixture of wood particles (92.5 wt %) and expanded polystyrene (7.5 wt %). This strategy was assumed to increase face layer density and generate a more pronounced vertical density profile, which is expected to improve panel properties. The density profile, mechanical properties and dimensional stability of the particleboards were investigated. Results showed that increasing the moisture content of face layer particles from 8% to 16% or using small-sized particle in face layer resulted in a more pronounced density profile, as well as using fiber in face layer. However, the higher density in the face layer was not necessarily related with better mechanical performance. The optimum physic-mechanical properties were obtained with the board of face layer made of 16% MC fiber,…
The environmental management accounting aims at capturing economic and environmental benefits and it should include externalities too. The aim of the paper is to propose a methodological approach for how to include non-market forest ecosystem services in the environmental management accounting so that the information could be used in economic analyzes. For this purpose, it is necessary to identify information relevant to related costs, sales revenues and the value of non-production ecosystem services. It is possible to perform the financial analysis needed for decision making in forest management. In the University Forest Establishment, the rated value of non-market ecosystem services was 3.2 million EUR, and this value was estimated to be twice as much as the value of market ecosystem services. In the Forest Plant Židlochovice, the value of non-market ecosystem services was 0.4 million EUR. Profitability increased from 1.346 to 4.093 and from 1.181 to 3.492.
A number of orchard woods have been investigated for suitability in the playgrounds, in the view of responders. In this sense, photos were taken of the specially prepared samples as stimuli, and there were three different groups of respondents. It was observed that the participants were effective in terms of age grouping and material preferences. For group A and C, majority of the participants preferred wooden elements for playground material. However, the majority of participants in group B (50.5%) preferred plastic elements, followed by wooden (31.5%), and then metal (18.0%). Moreover, it was seen that the most significant factors for selection of material for a playground should be safety for both Group A (79%), and C (76.5%), whereas it was aesthetic appearance, for group B (71%). Similar results were found for color properties of wood — the majority of participants of all three groups preferred light colored wooden elements in playgrounds. The results for the aesthetic preferences of wood species judged one-by-one and judged together received similar results. The preference scores for fig wood (Figus canica) is significantly higher than for other wood species, while “wood color” and “aesthetic appearance” are reliable positive predictors to aesthetic preferences.
Tang dynasty (AD 618–907) chairs were manufactured during an important period of Chinese furniture development. This paper aims to identify design elements that impact on people’s subjective impressions, so as to guide the design of Tang dynasty style chairs. The study combined eye tracking and Kansei evaluation methods to assess the semantic reception of Tang dynasty chairs. The results showed that the influential factors can be grouped into two main categories: decoration and shape. The decorative features of Tang dynasty chairs that have the most significant impact on visual attention were identified. The study determined that the backrests, armrests, and legs of Tang dynasty chairs design were the most important morphological features. Through these morphological features, we can define the Tang dynasty chair style, guide the design of modern Tang dynasty style chairs, and carry out targeted design of Tang dynasty chair style features.
For safety reasons, wood strength values are calculated based on their characteristic values. Brazilian national standard (NBR, in Portuguese “Norma Brasileira Regulamentadora”) 7190 (1997) establishes ratios for characteristic strength estimation and three forms of wood characterization, with an emphasis on the simplified procedure for common species, which allows obtaining the strength characteristic values through equations correlating different mechanical properties. The present work evaluates the accuracy of the relation proposed by NBR 7190 (1997) of shear strength along the grain (fv0,k) to compression strength along the grain (fc0,k) (fv0,k=0.12 fc0,k). 960 experimental measurements of shear and compression strength values were performed for 40 hardwood species, and the precision of the relation proposed by the Brazilian standard was evaluated using the analysis of variance (ANOVA) method. Linear, exponential, logarithmic, and geometric regression models were used as an alternative to the NBR relation for shear strength estimation. The statistical analysis revealed that the geometric regression is the model of best fit.
WOOD RESEARCH Volume 65, Number 2
This study investigated the shear strength of heat-treated solid wood of three species (beech, poplar, and fir) bonded with polyvinyl-acetate (PVA) adhesive reinforced by nanowollastonite (NW). Wood specimens were heat-treated at 165°C and 185°C, and then bonded using PVA reinforced by 5% and 10% of NW. Shear strength tests parallel to the grain of bonded specimens were performed according to ASTM D143-14 (2014). The results demonstrated that the shear strength was significantly dependent upon the density of the specimens. Heat treatment decreased the shear strength of the bonded specimens considerably. This was attributed to several factors, such as a reduction in polar groups in the cell wall, increased stiffness of the cell wall after heat treatment, and a reduction in the wettability of treated wood. However, NW acted as a reinforcement agent or extender in the complex, and eventually improved the shear bond strength. Moreover, the density functional theory (DFT) proved the bond formation between calcium atoms in the NW and hydroxyl groups of cell wall polymers. The overall results indicated the potential of NW to improve the bonding strength of heat-treated wood.
In the present study anatomical, histometrical, chemical and physical properties of the wood of 45-year old trees were determined. For this purpose, three trees were randomly cut at Sangdeh-Mazndaran located in the northern part of Iran. Disks and logs were removed at breast height to study the respective wood properties. Fiber length, fiber diameter, fiber lumen diameter, cell wall thickness as well as lignin and cellulose content of sapwood are superior to those of heartwood. Growth rings boundaries are fairly distinct and can be distinguished by only two to three compact fiber layers. The wood is diffuse-porous and vessels are small and predominately solitary, hardly visible to the naked eye on transverse sections. Most rays are 2-seriate interspersed with only few 3-seriate and uniseriate rays, and composed of procumbent body cells with occasional marginal rows of upright and/or square cells.
The article includes research related to utilization of waste wood which is primarily size reduced due to its voluminity for next processing for lower value added products for about last twenty years. Procedures and results obtained by different authors were considered in one study. In this review a wood waste downcycling was consider as a process of transformation of large size wood products over their lifetime to the new products, where a size reduction is one of the first operations needed to achieve to. Incineration of each way was excluded from the present review, but second-generation biofuels are considered as potential products for the future. Two points of research selection according to origin and according to products made of waste wood was applied in this review. Comparison shown that the most industrially applicable implementation of treated particles obtained from waste wood is intended to the composite materials production as particleboards, fibreboards, cement-bonded and wood-plastics.
To expand the application of furniture materials, the warm-cool and dry-wet tactile properties of the rice straw particleboard (RSP) surface were investigated. RSP substrates exhibiting densities equal to 757 and 554 kg.m-3 were sanded using different types of sandpaper (mesh 180#, 360#, and 600#). Psychological experiments on sensation were then conducted by bubbling for RSP substrates. By observing and comparing changes in warm-cool and dry-wet tactile properties between the RSP and other different materials, the effects of several variables on surface tactile properties, such as sandpaper types, RSP densities, and thermal conductivity of materials, were evaluated.
In this study, it is investigated that are calcite filler can be used in the production of medium density fiberboard. Chips have been to the process of cooking for 4-5 minutes in Asplund defibrator with the vapor pressure of 7-7.5 bar, and 180ºC temperature. 1.5% paraffin and 1% ammonium sulphate to be pulverized is added to fibers on the output of defibrillator and blowline line. Calcite fillers are prepared in a separate tank in order to use calcite instead of lignocellulosic fibers in the production of 1 m³ MDF. After that, urea formaldehyde glue is prepared as three different solutions which include the calcite, respectively with 3% (20 kg.m-3), 6% (40 kg.m-3), 9% (60 kg.m-3). The fibers are dried to moisture of 8%-12%. This press applies temperature about 185-190°C and pressure about 32-34 kg.m-2 to the mixture material for 270 seconds during pressing time. MDF panels (2100 x 4900 x 18 mm) were produced in the process. Both mechanical and physical experiments are performed on boards which are produced.
In this paper, oriented strand board (OSB) on both sides of the wood truss was used to strengthen the wood truss. The flexural behavior of the reinforced wood truss was studied. The results showed that OSB was an effective technical member to improve the flexural bearing capacity of wood truss. Besides, wood truss and OSB can be firmly combined by using glue bonding and screw connections. The screws served only to apply pressure to the glued joint. And the reinforced wood trusses had good synergy and overall stability. The initial bending stiffness and ultimate bending load of the reinforced wood trusses were increased by 203.20% and 234.39% respectively. Ultimate bending load and initial bending stiffness were improved a little by making the wood truss wider. Compared with the traditional wood truss, the reinforced wood truss had the advantages of simple connection mode, less wood consumption, no rolling machine and easy fabrication.
The paper deals with the research of electrical cables embedded in surface grooves of OSBs and its impact on the critical heat flux. An OSB type 3 board (structural board for use in dry or humid environments) and an electrical cable with fire reaction class B2ca have been investigated. Four different configurations of grooves were investigated. The first configuration consisted of an OSB without grooves (control sample). The second configuration consisted of an OSB with a single groove in the centre in which the electrical cable was mounted. In the third and fourth configurations, there were three and five grooves, respectively in which the electrical cables were mounted (the width of the grooves and the spacing between them was 9 mm). The critical heat flux was calculated from the ignition times at five different heat fluxes (30, 35, 40, 45 and 50 kW.m-2) by using a cone calorimeter. The obtained data showed that the OSB without grooves (first configuration) shows the lowest critical heat flux (8.6 kW.m-2) and the lowest standard deviation of ± 0.5 kW.m-2 (lower ignition resistance) compared to the other configurations (critical heat flux in the range from 9 to 10 kW.m-2 and standard deviation from 3.1…
In this paper, magnesia-bonded wood-wool panel was subjected to different times of wet and dry cycle to analyze their effects on the physical properties and the sound absorption property of the panel from macro and micro perspective. The results showed that with the increase of the wet and dry circle times, both MOE and thickness swelling decreased and the average absorption coefficient of the specimen increased.
Cultivation of highly productive stands of the Scots pine is a priority task of the forestry industry. This task should be solved using the methods based on the molecular genetic analysis. Following these methods carefully will allow improving the work quality and efficiency in the forest seed farming, to control successfully the stand phytosanitary condition, as well as to use DNA markers in the in vitro culture reproduction of tree species. Our studies have shown a high level of the Scots pine genetic diversity in forest seed orchards, which is confirmed by insignificant spread of values between similar studied characteristics when analyzing the Scots pine with high morphological characteristics, selected from natural populations. Thus, genetic monitoring of the objects of permanent forest seed base of this tree species should be introduced into practice of the forest selection seed farming.
In order to improve the mechanical properties of low-density wood, the densified wood was fabricated. Northeast China fast-growing poplar was firstly immersed in 50% glycerin for 24 h, and then compressed under 150°C to attain 60% compression ratio with different thermal modification time (0.5, 1, and 2 h). The set recovery, modulus of elasticity (MOE), modulus of rupture (MOR) and hardness of compressed wood were tested to assess the influence of thermal modification time and wet/dry cycles on mechanical properties and set recovery of compressed poplar with glycerin pretreatment. It can be found that the thermal modification time of 1 h can be more appropriate, the first wet/dry cycle has a significant effect on mechanical properties and set recovery of compressed wood due to the dilution of glycerin during the soaking.
In this study, it is aimed to determine the waste and productivity losses of Scots pine (Pinus sylvestris L.) logs that were exposed to blue stain degradation. In this context, a total of 39 timber production processes were analyzed in 7 different lumber managements using prism cutting and sharp cutting method. The main product yield and additional processing requirements were determined for flawed and flawless logs in blue stain damage. As a result of the study, it was determined that the blue stain degradation decreased the main product efficiency by 17% in the prism cutting method and by 33% in the sharp cutting method. Statistically significant differences were discovered between the efficiency values obtained as a consequence of cutting flawed and flawless logs with prism and sharp cutting methods. In addition, additional processing requirements were determined in the sharp mowing method.
In this paper, the influence law of cutting tools with different blade shapes in the process of wood milling was studied. Keeping the cutting speed, cutting depth, cutting width unchanged, the blade shapes of milling cutter were the research object, the cutting force, cutting vibration, and chip morphology change under different feed rate were discussed, the surface roughness of the processed material was analyzed under down milling and up milling. The results showed that when the feed rate increased from 6 m.min-1 to 14 m.min-1, the cutting force in up milling was less than that in downing milling, the cutting vibration of upright milling cutter with spiral curved blade was the smallest, it increased gradually in the range of 13.6 m.s-2 - 27.4 m.s-2 in up milling. On the whole, the surface roughness of the workpiece in down milling was better than that in up milling. The experimental study on the cutter milling blade shapes had a guiding significance for improving the precision of surface machining and provided a theoretical reference for the selection of process parameters in the milling process.
The timber column seismic response has been analyzed when it has been subjected to near-fault ground motion. The cyclic displacement and cyclic strain have been investigated. It needs to indicate in most of the literature acceleration history of earthquake used in the numerical analysis is not well clear for the reader. The results showed that the damping ratio, strain energy, and nonlinear deformation were changed in respect to the frame geometry. The innovation of this paper is to develop cycling graphs by means ABAQUS for study timber column seismic response and improve the concept of strain energy in understanding displacement mechanism.
To explore the feasibility of hem-fir for CLT products, this work addressed the exploratory and pilot plant studies of hem-fir cross-laminated timber (CLT) products through mechanical tests. The hem-fir lumber was procured and then stress-graded based on dynamic modulus of elasticity (MOE). The resulted 5-ply prototype CLT products were then tested non-destructively and 3-ply pilot plant hem-fir CLT was tested destructively. The results showed that bending performance of hem-fir CLT panel can be predicted. Considering cost-competitiveness and end applications of hem-fir CLT products, the panel structure can be optimized based on the stress-graded data of hem-fir lumber.
The elastic properties of six wood species were determined using the resonant beam technique. By stimulation of transverse vibrations and analyzing the responding oscillations of carefully prepared rectangular beams of wood, simultaneous determination of one Young’s modulus and two shear-moduli on one specimen is possible. Using three different cutting orientations along the principal material directions all three Young’s moduli and three shear moduli can be determined. This paper presents the application of this technique to six wood species: two softwoods, two hardwoods and two tropical woods.
WOOD RESEARCH Volume 65, Number 3
In this study the influence of thermal modification on the resistance of wood to the impact of water and mechanical properties and to compare the durability of thermally modified and coated wood products operating in wet conditions was investigated. It was found that the weight of thermally unmodified non-coated oak wood after 48 h of soaking increased on average up to ~ 15%, and the weight of coated oak wood increased up to ~ 8%. If wood was thermally modified, the weight of non-coated oak wood increased up to ~ 9%, and the weight of coated oak wood increased up to ~ 5%. After 168 h of soaking these change is about 2 times larger. In the case of pine wood compared to oak wood these change of weight after 48 h is about 2.0 – 2.4 times and after 168 h about 1.4 - 2.0 larger. It can be stated that wooden constructions intended to be used in very wet conditions should be made of thermally modified wood without coating. Thermally modified wood will have greater dimensional and shape stability. Thermal modification reduces the swell up to 1.6 times in the case of oak, more than 2 times in…
Non-destructive testing of wood panels by either resonance or time-of-flight (TOF) methods provides possibilities for predicting their static bending properties. In the present study, three non-destructive devices (BING - Beam Identification by Non-destructive Grading by CIRAD, Montpellier, France, Fakopp Ultrasonic Timer and Sylvatest TRIO) were used for measuring the dynamic stiffness of different particleboard types. Fakopp Ultrasonic Timer and Sylvatest TRIO produce ultrasonic pulses to measure the sound velocity while BING uses resonance frequencies. Commercially produced particleboards with different thickness and densities were used to measure the dynamic modulus of elasticity (MOEdyn) in two directions (parallel and perpendicular to the production line) and at three different humidity levels (dry - 35%, standard - 65% and wet - 85% RH in constant temperature of 20°C ). MOEdyn of particleboards were correlated with the static moduli of elasticity (MOEstat) and rupture (MORstat). It was found that the non-destructive methods gave higher MOEdyn values in both production directions than that of MOEstat values. MOEdyn was found to decrease from dry to wet conditions. A very strong and statistically significant correlation existed between MOEdyn and static bending properties. MOEdyn correlated stronger to MOEstat than MORstat. At different humidity level, all three methods- Fakopp Ultrasonic…
To improve the surface-finishing performance and enhance the protection of surface coatings, this study employed metallization treatment of fast-growing poplar through an orthogonal experiment. The poplar specimens were impregnated using a low-melting point alloy at different temperatures (75°C, 85°C, 95°C), pressures (0.5MPa, 1 MPa, 1.5 MPa), and times (0.5h, 1h, 2h) to obtain the optimum process parameters and determine the paint film adhesion of metalized poplar. The test results showed that the impregnation effect was obvious with an increase in the pressure and time. The optimum process parameters were 0.5 MPa, 85°C, and 1 h. Contact angle of the treated wood increased, the surface free energy dropped to some extent, wetting property of tread wood decreased. Whether the treated wood or the untreated wood, film adhesion of treated wood got a higher level. After anti-aging treatment, the treated poplar still had a higher level of film adhesion.
In this study, each of the commonly used two types of woods (softwood and hardwood) from five species was studied. All wood species show a systematic trend to change to higher values of surface roughness with natural weathering progress. The Black pine, Calabrian pine and beech wood samples show a more or less smooth trend, whereas basswood gives the highest surface roughness changes under all conditions. However, the hardwood species, except basswood, have higher hardness properties both initially and at the end of weathering process when compared to softwoods. The surface discoloration that occurs is clearly visible as a natural texturing. However, the degree of, and the pattern of texturing, may vary with different kinds of woods; the color changes also vary to some extent. It was revealed that the discoloration is strongly dependent on the botanical origin of wood species. The lower lightness changes (ΔL %) were found for all three pine species (16.2 to 37.2%) when compared to fir (54.9%) and spruce samples (91.8%). The Scotch pine wood showed highest values for the contribution of red color initially and low redness change on the surface after the weathering process, among the other softwood species.
Scots pine wood (Pinus sylvestris L.) is the most common wood material used in historical buildings in many parts of Central and Eastern Europe. Experiments were conducted natural aged wood (263 – 459 years old), extracted from construction elements of four historical buildings (from seven construction elements), and contemporary wood extracted from 5 construction elements. A strong relationship was observed between density and static bending strength (MOR) of natural aged wood (R2 = 0.5599), and also of contemporary timber (R2 = 0.7863). Antique wood compared to contemporary wood with the same average moisture content and density is characterized by significantly lower modules (static and dynamic), the speed of ultrasonic waves transitions, and bending strength. Differences in these properties increase with increasing wood density.
A new mutant E. ulmoides with red xylem is found, and this red color will gradually metabolize over time. Comparisons of chemical properties and metabolites of xylem between the mutant and wild type were analyzed in this study in order to discover the cause of the red mutation. The results showed that the acid-insoluble lignin content of mutant type was about 13.83% higher than that of wild type, but the crude protein of wild type was almost 2 times of mutant type. Meanwhile, 6 most important amino acids and amino acid derivatives were detected, which had significant correlation with crude protein. Additionally, the contents of organic acids, polyphenols and alkaloids in the mutant type were 243%, 316% and 281% of those in the wild type, respectively, while the contents of flavonoids and phenolamines contents were 78.8% and 27.3% of those in the wild type, respectively. These results will provide an important reference for understanding the wood color variation during growing.
Three different types of paper with different coatings have been used in order to study the influence of gaseous plasma treatment on surface properties of paper. Radio frequency (RF) oxygen plasma was used for treatment of papers that contain different parts of organic and inorganic components in their coatings. Surface properties like surface morphology, roughness, surface energy, wettability, and chemistry were studied. The influence of plasma modification was also studied in terms of printability and paper gloss, which are one of the key parameters that dictate the use of such paper in desired applications. The results indicate that plasma modification of different types of coatings indeed influences paper printability as well as gloss function, which was shown to be highly connected with surface morphology, as micro- and nanopores were opened or formed due to selective plasma etching of organic part of the coating. Moreover, significant increase in surface energy was observed on all plasma treated papers, however this seemed not to influence much on the printing and gloss properties.
As newsprints, mostly made from recycled wood pulp, are not high quality papers according to its optical, mechanical and chemical characteristics, in this research the usage of straw pulp as an alternative raw material was analyzed. For that purpose, straw pulp was mixed with recycled wood pulp and strength properties of laboratory made papers were determined according to TAPPI standards. Selection of agricultural waste for preparing straw pulp was based on annual yield of crop species (Triticum spp., Hordeum vulgare L. and Triticale sp.). Results indicated that straw pulp can be efficiently used in portions up to 20% as a substitute for wood fibers or as an additive in order to obtain particular newsprint properties.
The influence of proportions of bleached birch, eucalyptus, beech kraft pulps as well as the bleached aspen chemi-thermomechanical pulp (BCTMP) in the mixture with bleached pine kraft pulp on tissue paper properties was compared. Increase of bleached beech kraft pulp and aspen BCTMP proportion in a mixture with bleached pine kraft pulp leads to significant rise of porosity ε as well as bulk. The water absorption after immersion increased significantly with increase of aspen BCTMP content in the mixture while other hardwood pulps in the mixture had only moderate impact. Increasing of bleached beech and eucalyptus kraft pulps content in the mixture continually increased initial water absorption. As a result of blending of bleached birch kraft pulp with bleached pine kraft pulp, bulk softness improved and the tensile index increased slightly. The increased content of bleached birch and beech kraft pulp in the mixture increased the brightness while the addition of aspen BCTMP and bleached eucalyptus kraft pulp increased of coordinate b* value. Mixed pulps with properties suitable for different types of hygienic products were selected.
The article is devoted to the study of the gene pool formation mechanisms of arboreal plant populations at the sites of mining and processing of mineral resources and may be useful in managing the processes of natural forest remediation of disturbed lands. The aim of the research is to study the genetic diversity and spatial differentiation of the Scots pine (Pinus sylvestris L.) undergrowth thriving on the industrial waste discharge of the Uchaly Mining and Processing Plant (the Southern Urals). Isoenzymes of 7 enzymes were used as markers (encoded by 10 polymorphic loci Aat-1, Aat-2 and Aat-3, Gdh-1, Fdh-1, Lap-1, Lap-1, Skdh-1, 6-Pgdh-1 and Dia-1), separated by polyacrylamide disc electrophoresis. Genetic variability of the undergrowth under the forest canopy (7 samples, average number of avenues per locus A = 2.3-2.8, the observed heterozygosity was HO = 0.207 - 0.260, the expected heterozygosity HE = 0.201 - 0.273) and in industrial waste discharges (4 samples, A = 1.9 - 3.1, HO = 0.225 - 0.277; HE = 0.240 -0.298) varies over a wide range. In the parent stand, the observed heterozygosity (HO = 0.203) was lower than in any of the undergrowth samples. A comparatively high genetic differentiation of the undergrowth…
In this paper, the art-of-the-state of heat-induced inkless eco-printing (HIEP) technology in recent years was summarized and prospected, mainly from the printing effect, degree of carbonization, environmental impact and feasibility. The main results were as following: (1) The paper used in HIEP is predominantly yellow in color, which enables a practical printing effect. (2) After HIEP, the paper exhibits no significant carbonized microstructure and keeps its high strength. (3) HIEP is an ecologically and environmentally preferable technology. Only a small amount of toxic products is generated, and no carcinogens are emitted. (4) No significant damage to the paper is evident following HIEP, as the degree of heat experienced during HIEP is far below that experienced during a thermogravimetric (TG) experiment. Additionally, the evaporated water has a buffering effect. Based on the previous research results, this paper finally pointed out the possible research direction in terms of discoloration mechanism and printing effect, environmental impact improvement, paper damage mechanism and strength during HIEP, high-temperature printing head installation and relevant techniques, optimization of printing process parameters.
The objective of this study was to determine the effects of the glass fiber fabric reinforced holes in MDF, PB, OSB, and PL. The fabrics of 19 mm or 50 mm wide were used to reinforce the edge or flat surface of test specimens. The experimental sample groups were formed in 34 different ways. Three different holes configurations were prepared. The samples were subjected to the 3 points bend testing in the flatwise and edgewise directions. As a result of tests, bending strength and modulus of elasticity were determined. The data obtained separately in flatwise and edgewise bending tests were subjected to multiple variance analysis. According to experiment results, the lowest values were obtained in the “fabricless” in both tests. The lowest value was obtained as 12.35 N.m-2 (in PB material) in the group 12, which has samples with the fabric on the edge and 2 holes on the surface in the flatwise test, while the highest value was obtained as 49988 N.m-2 (in PL material) in the group 19, which has samples with the fabric on the bottom edge and holeless in the edgewise test. According to the materials, the lowest values were as 18.32 N.m-2 in PB material,…
The aim of this study was to investigate the cold/warm sensations of materials used in desktop when forearms touching desktop. Both experimental tests and subjective evaluations were conducted in this study. A device was developed used to simulate forearm in order to replace subjects. Five men and five women were selected and introduced to six types of materials and two types of environmental temperatures in the tests. The results showed that the effects of environmental temperature on contact temperature of all tested materials were statistically significant, and the differences among wood and wood based materials, plastic materials, and artificial stone were also statistically significant. The device developed in this study was qualified to measure the contacting temperature between forearm and desktop sustainably and steadily, which can reduce the error introduced by subjects. Although qualitative relation was found between contact temperature and subjective evaluations, no quantitative correlation was proved.
The aim of the presented study is to find the best solution for the cross-sectional dimensions of timber-concrete composite (TCC) beam by focusing on serviceability limit state verification and cost of the beam, simultaneously. The population of 10.000 samples of the observed variables according to the predetermined ranges using Monte Carlo sampling method was generated. In order to find a number of Pareto-optimal solutions on the Pareto front, the weighted sum method was employed using original algorithm. The results have shown that minimum relative cost of the TCC beam can be increased even by 26.6% if the rheological effects that are neglected by the Effective modulus method are counted in the calculation of the final deflection. The presented trade-off strategy in design of the TCC beams has shown that with the slight increase of relative cost compared to the minimum, it is possible to get Pareto optimal design solution of the TCC beam that has drastically decreased final deflection and therefore is a more reliable design solution.
This research deals with the impact of the microclimate on historical wooden buildings exposed to open sea streams. The Florya Ataturk Marine Mansion in Istanbul, erected on the sea, totally defenceless to weather and sea effects, has been selected as representative case study for many other buildings located in Bosphorus line. In order to address the effect of the environment on the building exposed to open sea streams microclimatic data were collected for one year. The synergistic effect of the sea-salt aerosol and microclimatic conditions were discussed for the assessment of the impact of the marine environment on the durability of the Mansion, identifying the more vulnerable parts of the building as well as the more critical periods. The results indicate that while moisture content changes from 20.9% to 36.7% and temperature changes from 14.1°C to 28.7°C, thermal conductivity coefficient changes from 0.18 W.m-1K-1 to 0.26 W.m-1K-1, according to the facade of the building and the season as similar to previous studies.
WOOD RESEARCH Volume 65, Number 4
The present study investigated the physiological and biochemical mechanism of extracts derived from Cinnamomum camphora (L.) Presl. The methanol and chloroform extracts of C. camphora xylem exhibited inhibitory activity against oxygen consumption in Coriolus versicolor and Gloeophyllum trabeum. The inhibitory effect of cellulose secreted by G. trabeum was concentration-dependent. The application of the ethyl acetate extracts of C. camphora xylem on the G. trabeum hyphae resulted in an improvement in electric conductivity, which followed a concentration-dependent fashion. Protein permeability increased with higher concentrations of the ethyl acetate extracts of C. camphora xylem. This research provided theoretical basis for understanding of the physiological and biochemical mechanisms of C. camphora extracts inhibit wood-decay fungi and the development of natural extracts as wood preservatives.
The present work had the goal of assessing the wood quality through physical-mechanical properties of six 5-year old eucalyptus clones currently planted in northern Mato Grosso State, Brazil. The following clones were assessed, five of them Eucalyptus grandis x Eucalyptus urophylla hybrids and one a clone of Eucalyptus camaldulensis. The physical-mechanical properties were basic density as a function of tree height; pith-to-bark direction; linear, tangential and radial shrinkage; and anisotropic coefficient, longitudinal and parallel compression and static bending strengths; and hardness. Eucalyptus grandis x Eucalyptus urophylla hybrids showed the best wood quality. Concerning to mechanical results, the clones reached intermediate values of strength and rigidity, qualifying them for use in structural applications with less stringent requirements. Considering that all the clones had juvenile wood, the mechanical properties were satisfactory, making the clones suitable for industrial uses.
Due to the fact that wood roughness measurement results measured with stylus and optical methods are not always comparable a new calibration method was proposed. In order to compare the surface roughness parameters of the stylus tactile 2D roughness parameters and the optical 3D roughness parameters a systematic experiment has been carried out on fourteen wood species. The essence of this calibration method is the use of metal calibration etalons for Rz = 20 μm and Rz = 30 μm and the filter option of the optical measuring apparatus. After the calibration process, the roughness profiles taken with the optical and stylus units were much closer each to other decreasing the difference in the measurement results of the two systems. Our study prove that the laser triangular method is less usable for the planed wood surfaces.
Based on the principle of tree chronology, this paper measures tracheid morphological characteristics, ring width, and latewood rate of harvested wood from Cupressus funebris plantation in Deyang, Sichuan Province. Using meteorological data of average temperature, precipitation, relative humidity, sunshine percentage, and average ground temperature from 1983 to 2015, correlation analyses were conducted. The results of the analysis showed that the correlation between tracheid morphological characteristics, ring width, and latewood rate was not consistent with a single climatic factor. Moreover, the correlation between tracheid morphological characteristics and climatic factors, and the correlation between ring width, latewood rate, and climatic factors were significantly different. Temperature was the main limiting factor for ring width and latewood rate. In addition, relative humidity was positively correlated with ring width and negatively correlated with most indicators of tracheid morphological characteristics. Fewer indicators were affected by sunshine percentage. Meanwhile, precipitation was not significantly correlated with ring width and latewood rate. In conclusion, the correlation between various indicators and climate factors was from high to low in order of temperature, relative humidity, sunshine percentage, and precipitation.
The effect of steam explosion on enzymatic hydrolysis of various parts of poplar tree (heartwood, sapwood and 1-year coppice) was investigated. These parts were milled, the obtained sawdust was chemically analysed and then steam explosion of 0.7 mm poplar particles at temperature of 205°C was performed. Concentration of monomers obtained after enzymatic hydrolysis was considered as the main indicator for cellulose accessibility. Analysis of high performance liquid chromatography showed that non-treated poplar sawdust does not enable sufficient cellulose accessibility, while excessively high temperature and rapid pressure release resulted in substantial breakdown of polysaccharides and lignin and formation of inhibitors. The concentration of monomers increased gradually in the order of coppice, sapwood and heartwood. Steam exploded heartwood gave the maximum monosaccharides concentration of 90.0 g.L-1 after 72 hours of enzymatic hydrolysis. However, glucose concentration culminated after 48 hours of this hydrolysis. This corresponds to the best holocellulose accessibility for enzymes. The maximum concentration of inhibitors (9.3 g.L-1) was determined for poplar coppice after 24 hours of enzymatic hydrolysis.
In this study, the ACQ-D preservative treatments of poplar wood were carried out using the method of living tree injection treatment and the leachability was examined by comparing with the traditional treatment methods, namely, immersion and pressure treatment. In addition, the effects of injection experiment on the soil environment and preservative stability in wood were examined. The results showed that the effect of injection experiment on soil environment around the treated trees was insignificant and the preservative stability of the injection treatment was the best among three methods. ACQ-D preservatives leached easily as the increase of concentration. The retention of preservative after pressure treatment was greater than that of the injection and immersion treatment, but after the leaching tests, three methods had the same preservation grade.
The paper deals with testing fire resistance of a vertical wooden building construction made of CLT panels subjected to the medium-scale test of the fire resistance. A model test of fire resistance with the ceramic radiation panel as the radiation heat source, with achievable temperature of radiation surface of 935°C at maximum was used. The aim of the experiment was to assess the experiment sample whether it meets the request of the thermal insulation and integrity under thermal loading of the model fire for 30 min. The test resulted in the increase of temperatures on observed thermocouples and assessment of the integrity on the unexposed side of the CLT panel. The construction clearly resisted the effects of the radiation heat during 30 min and maintained the observed criteria of fire resistance. Charred layer of the CLT panel created on the surface of the exposed side in the thickness of 20 mm inhibited the heat transfer into the further layers of construction.
In this paper, the effects of atmospheric pressure, vacuum and vacuum pressure impregnation on the permeability of alkaline copper quat in poplar were studied, and the permeability and fixation of preservatives were improved by pretreatment of poplar. The results show that the volume loading of wood can be increased by about 60 - 150% after 30 min of vacuum treatment, so the vacuum method is a simple and efficient preservation treatment method. In addition, ethanol treatment, heat treatment and microwave treatment can increase the fixation rate of copper ions by 5 - 10%, but the fixation rate of copper ions dropped by 17.83% after NaOH treatment for the dissolution of partial hemicellulose.
In this study, the use of the urea was investigated as an additive in soda pulping of Populus deltoides in comparison with the conventional soda and Kraft processes. Urea was used at the ratios of 1.5%, 3%, 4.5%, and, 6% based on the dry weight of wood in the soda process. The constant factors were determined for each distinct cooking of soda, soda-urea, and Kraft treatments. The dry weight of the chips was 150 g, the ratio of the liquor to wood (L/W) 4: 1, the maximum temperature 170°C and active alkaline content 18% (based on Na2O). Cooking time, the only changing factor, was varied from 30 to 330 min depending on the type of cooking. Besides, the sulfidity ratio was 25% for all Kraft treatments. After ending pulping time, the pulp samples were fully washed. Then, the screen accepts and the screen rejects were evaluated using a 20 and a 200-mesh screen. The observation shows that the more urea usage is in a pulping liquor, the more total yield, however, the screen reject value unexpectedly increased. Hence, the optimum values were determined by 1.5% and 3%. The investigation of handsheet samples indicated an increment trend of mechanical strengths with…
In this study the effect heat treatment process parameters (temperature, duration and heating rate) on the surface color of rubber wood was evaluated. The color of the rubber wood was determined using CIE L*a*b* system before and after the heat treatment. The colorimetric properties, including total color difference (ΔE*), lightness index (L*), red-green index (a*), and yellow-blue index (b*), were investigated at different treatment conditions. The results of analysis of variance (ANOVA) indicate that the heat treatment temperature has a significant effect on the colorimetric properties of the heat-treated rubber wood, duration and heating rate has no effect. Within the experimental range, as the heat treatment temperature and duration increasing, the color of the rubber wood gradually deepens. In order to achieve a surface color like the teak wood, the optimum process conditions are heat treatment temperature 190°C, duration 4 h, heating rate 10°C.h-1.
Prestressing force and its change is one of the key factors that affect wooden constructions, especially those using methods of transverse prestressing. To achieve a description of a prestress force (P) in transversally prestressed wooden constructions a simulated experiment was done. Prestressing force, external temperature, and moisture were measured during 669 days. The main goal of this article was to model the primary losses of the prestress force at the spruce element of the 138 x 138 mm cross-section with the sensor installed. For this purpose, all measurements were statistically analyzed and the period of primary loss was found. During this period the prestress force was decreasing with time mainly and the influence of temperature and moisture could be omitted. Based on this analysis a mathematical model of losses of the prestress force was found as P = 8.538-0.014.day.
The article shows the method for prediction of corrugated board properties based on automatic generation of a database containing material compositions of all the boards possible to be produced by a given manufacturer. With their large number it is not possible to carry out on the basis of measurements made on earlier manufactured products. As a result of the tests carried out with the use of data provided by the corrugated board manufacturer, it was found that using his paper materials and machinery it was possible to more than double increase the bending stiffness and edge crush resistance indexes of produced board. In some cases, the options for improving the indexes are slightly smaller, e.g. bending stiffness in the cross direction of three-layer board with flute C, the mentioned manufacturer can increase by approx. 40% of the maximum value obtained so far.
Essential oil volatilization of Cinnamomum camphora (L.) Presl can positively affect indoor air quality through insect dispersal, antibacterial effects, and inhibiting decay, and thus is an important economic species in China. Camphor is the most abundant aromatic compound in C. camphora, although how time and temperature affect the release of the camphor is unknown. To address this question Cinnamomum camphora (C. camphora) wood was investigated using headspace gas chromatography (HS-GC). Camphor decreased with increasing detection times over temperatures of different temperature. During the detection, the release rate of camphor decreased rapidly with increased heating time in the first 2.5 h, and leveled-off after 2.5 h. The release of camphor at different temperatures was linear between 0 ~ 1.4 h. By fitting this linear model with reaction temperature camphor release could be expressed as Y = -75.369 + 2.3786.T + (41.125 - 1.1972.T). Evaluating the release of camphor from C. camphora wood and creating a model may be useful for promoting its application in the medical and chemical industries.
The objective of this research was to evaluate the strength of corner joints of box shaped furniture made from eastern red cedar (Juniperus virginiana L.) and corn starch binder southern sample. Various types of corner joint techniques were evaluated (glued, glued and screwed, and glued with dowel corners). Eastern redcedar particle samples with corn starch and glutaraldehyde were used. Overlaid and non-overlaid particleboards along with sandwich panels were used at “L” type corner joints. Tension and compression strength moment values were measured. Particleboard panel joint mounted with dowel resulted in the highest tension strength moment values followed by the specimens having a sandwich-type configuration combined with a dowel. Particleboard and overlaid sandwich-type panels glued with polyvinyl acetate (PVAc) had the lowest strength values. It appears that composite panels manufactured with modified starch have the potential to be used for corner joints.
A wood protection method using electric fields to inhibit wood decay by brown rot fungi has been investigated in laboratory trials. Glued and non-glued wood samples were exposed to fungal attack for 6 weeks in Petri dishes and showed significantly reduced mass loss when connected to a low pulsed electric field (LPEF). The mass loss of LPEF-protected samples was in average lower than 10%, with a wood moisture content above 40%. The mass loss of untreated wood samples was above 30% in average. The glue line did not represent a barrier for the electric field in the test setup (a), where the glue line was applied on the transverse section of two glue-jointed wood sample halves. A test setup with two glue lines at the tangential side of three jointed wood samples, showed only slightly higher mass loss compared with wood samples consisting of two jointed halves. It is concluded that glue lines using the MUF glue mix used in this study do not impede the protective effect of LPEF.
WOOD RESEARCH Volume 65, Number 5
Whereas hygroscopicity an leaching resistance often have a bad influence on performance of fire-retardants, in this work, nano-SiO2 sol was added to different nitrogen-phosphorus-boron fire retardants to make four new compounds to impregnate bamboo strips, named: (1) ammonium dihydrogen phosphate + disodium octaborate tetrahydrate (AD), (2) ammonium dihydrogen phosphate + disodium octaborate tetrahydrate + nano-SiO2 sol (ADS), (3) ammonium dihydrogen phosphate + boric acid (AB), and (4) ammonium dihydrogen phosphate + boric acid + nano-SiO2 sol (ABS). After that, the hygroscopicity, leaching resistance and thermal stability were studied by scanning electron microscopy (SEM), energy dispersive X-Ray spectroscopy (EDX), thermogravimetric (TG) and fourier-transform infrared spectrometer (FTIR), and the optimal compound fire retardant is ABS. The results show that the addition of nano-SiO2 sol can not only reduce the hygroscopicity of fire-retardant bamboo strips effectively, but also improve its leaching resistance. The results also indicate that compared with non-fire-retardant bamboo strips, the thermal stability of bamboo strips treated with AB and ABS was improved significantly, and there was no significant difference between AB and ABS.
This article is focused on research into the racking strength and stiffness of mechanically jointed cross laminated timber shear walls considering the influence of fasteners between the layers of boards on the stiffness of panels. The work includes an experimental analysis and analytical model. The experimental analysis included tests of the shear wall panels, tests of the specimens to determine the stiffness at the joint of the layers and material tests. The analytical model based on the component method allows the determination of the racking strength and horizontal displacement of the shear wall in dependence on the number of layers and the number of fasteners in the joint of layers, parameters of the anchorage to the substructure and applied external load. The outputs of the numerical model and the results of the experiments agree relatively well. The largest relative displacement error is 18%.
This research presents the effects of lamina thickness on flexural and creep performances of glulam timber. Flexural test results indicated that nonlinear load-displacement curve could be defined as both exponential and power functions. Lamina thickness was not affected to nonlinear curve, especially at initial linear relationship. Slightly different of 2.92% for nonlinear function parameters was obtained. For flexural creep test due to three levels of sustained load for 1,000 hours, only secondary creep stage behaviors without delamination were observed for all glulam timbers while average relative creep was 1.66. Effect of lamina thickness was also not found for creep performance. Finally, creep models have been developed including Bailey-Norton, adjusted Pickel, simplified Pickel, and Dorn models and found that Bailey-Norton and the adjusted Pickel models gave a good correlation with experiment and were the suitable models which could be used to predict long-term flexural creep behavior for various stress levels.
The present study deals with a production of pine particleboards using the sugarcane bagasse content and using castor-oil based bicomponent polyurethane resin and urea-formaldehyde resin. The influence of incorporation of sugarcane bagasse on the physical and mechanical properties of the composites was evaluated. The particleboards were produced according Brazilian standard ABNT NBR 14810, but performance requirements have been analyzed using Brazilian and international standards, as well. Treatment 2, using PU resin, were considered the best treatment using pine residue and sugarcane bagasse, presenting physical properties values 60% lower and mechanical properties 65% higher on average when compared with panel without sugarcane bagasse, indicating the good performance of sugarcane incorporation and the possibility of its use on commercial purpose for thermal and acoustic insulation. The addition of sugarcane bagasse improved physical and mechanical properties of particleboards when compared to panels manufactured from pine wood particles only. Statistical analysis indicated that moisture content and bagasse content were significant, enhancing properties when compared with reference treatments.
Composite electrode material composed of MnO2 nanowires and wood-derived activated carbon hollow fibres (Mn@ACHFs) was successfully fabricated by in situ hydrothermal method. In this work, MnO2 nanowires were developed by adjusting the mass ratio of potassium permanganate and wood activated carbon hollow fibres (ACHF). The ACHF with hierarchical porous structure served not only as the support for the growth of MnO2 particles, but also as the electric double layer capacitance for the composite electrode. The Mn@ACHFs exhibited an outstanding specific capacitance of 420 F.g-1 at 1 A.g-1 and cycle stability with 99.7% capacitance retention after 5000 cycles at 5 A.g-1. Electrochemical characteristics of the prepared composites are attributed to the synergetic effect of the double layer capacitance of the hierarchical porous ACHF and the layered structure of MnO2, which can efficiently enhance the conductivity and stability of the electrodes.
The objective of this study was to investigate the properties of nipa front particleboard bonded using the combination of sucrose and citric acid, and the effect of different pressing temperature. The results showed that the adding citric acid to sucrose and increasing pressing temperature increased the physical and mechanical properties of the nipa fronds particleboards. FTIR analysis results indicated that the peak intensity of C=O ester group and C–O–C hemiacetal group increased and the hydroxyl OH groups decreased with increasing pressing temperature and addition of citric acid, which indicated that crosslinking between sucrose and citric acid occurred. TG-DTA analysis confirm that increasing pressing temperature and addition of citric acid to sucrose increasing thermal stability of nipa fronds particleboards, which is suspected caused by the polycondensation reaction between sucrose and citric acid.
This paper aims to identify the decay types and investigate the chemical alterations in the three types of fungal decayed archaeological wood from Dongshan Han Tomb M6 (ca. 200-100 B.C.) in Taiyuan City, China. Microscopy, FT-IR, 13C NMR and XPS were adopted to reveal the features of the samples. The results show that from the microscopic and chemical perspectives, these samples are consistent with the characteristics of brown-rot, white-rot and soft-rot. However, all the samples show the accumulation of carboxylic acids or carboxylate salts from extensive oxidation of lignin, which were not observed in artificial fungal decayed wood. Moreover, different fungal decay types and pH values of the samples corresponding to the alternative forms of carboxylic acid or carboxylate salt are considered to be influenced by combined factors, such as the position in the tomb, groundwater level, moisture content, oxygen availability, etc. This study may provide a reference for the deterioration and conservation of fungal decayed wooden artifacts in the tomb of northern China where alkaline loess is the main soil type.
In order to elaborate design guidelines for developing efficient and possibly most energy saving mills for comminuting carpentry, OSB and MDF waste, there have been performed some tests aimed at torque demand on the working unit of the machinery participating in that process. The tests were carried out on a cylindrical wood chipper. There were indicated the maximum, minimum and average values of the torque, indispensable for the comminution of boards with defined geometric sizes (5 - 50 mm wide ) and thickness (3 - 28 mm). The value of torque required in the comminution of carpentry waste increases with growing cross section, and the torque vs. cross section relation is approximately linear. The presented values may constitute not only a set of input data indispensable for modeling the power which is necessary for the comminution process, but they can also enable the validation of the existing cutting models with a single cylinder cutter.
The aim of this study is to help to create a healthier environment by measuring the noise levels in the furniture and lumber sectors of forest products industry. In this study, noise measurement for approximately 3 min has been conducted in 4 measurement spots in the side of the machinery, in the factory entrance and in full and empty state for each machinery; from 3 different chosen spots in enterprises producing lumber. Measurements have been recorded as 720, from each machine as 36 measurements, with the condition to be recorded every 5 sec for 3 min. For this purpose, noise measurements have been carried out in 17 workplaces producing lumber and results have been compared statistically. As a result of the obtained findings, it is understood that the noise levels of thickness machinery don’t exceed the value for the upper limit stated in the regulations. However, vertical wood band sawmill and band saw machines have been observed to go over this limit. Besides, some factors of planning and multi slitting machine don’t exceed this limit, some of them exceed. As a result, it has been conducted that when noise levels of machinery used in the lumber industry enterprises exceed the…
In this study, wood protectants were prepared by using manganese chloride, potassium carbonate, borax and nano colloidal silica sol. Effects of the wood protectants on decay resistance, anti-mold property and fire resistance of Pinus massoniana Lamb. were discussed. The results indicated that the optimal formula of the protectant was composed of 20% colloidal silica sol and 8% modifier (manganese chloride + potassium carbonate + borax). Under this formula, the protectant had good permeability and fluidity, accompanied with synergistic effect between colloidal silica sol and modifier. Pinus massoniana Lamb. treated by the protectant with this formula showed good decay resistance, and its mass loss rates after corrosion by Gloeophyllum trabeum and Coriolus versicolor were respectively about 21% and 19%, lower than those of the control group. This indicated that the preferred samples reached I-level decay resistance according to Chinese Forestry Industrial Standards LY/T 1283-2011. Moreover, Pinus massoniana Lamb. under this formula had good anti-mold property, manifested by 100% resistance to Aspergillus niger V. Tiegh and Trichoderma viride Pers. ex Fr. The treated Pinus massoniana Lamb. also showed good fire resistance with the oxygen indexes before and after leaching respectively at 20.45% and 13.64%, higher than those of the control group. It…
In present study, Pleurotus ostreatus, Ganoderma lucidum, Ganoderma ahmadii, Ganoderma applanatum, Ganoderma australe, Ganoderma colossus, Ganoderma flexipes, Ganoderma resinaceum, Ganoderma tornatum, Trametes hirsutus, Trametes proteus, Trametes pubescens, Trametes tephroleucus, Trametes versicolor, Trametes insularis, Fomes fomentarius, Fomes scruposus, Fomitopsis semitostus, Fomes lividus, Fomes linteus, Phellinus allardii, Phellinus badius, Phellinus callimorphus, Phellinus caryophylli, Phellinus pini, Phellinus torulosus, Poria ravenalae, Poria versipora, Poria paradoxa, Poria latemarginata, Heterobasidion insulare, Schizophyllum commune, Schizophyllum radiatum, Daldinia sp., Xylaria sp., were collected, isolated, identified and then screened qualitatively for their laccase activity. Among all the collected and tested fungi Pleurotus ostreatus 008 and 016, Ganoderma lucidum 101,102 and 104 were highly efficient in terms of laccase production. The potent strains were further subjected to Quantitative laccase bioassay for partial purification and characterization of industrially important enzyme.
In this paper, the three-layer Canadian hemlock CLT panel was designed to test the elastic modulus and bending strength of CLT specimens by four-point bending method. The interlaminar shear of CLT specimens was tested by short-span three-point bending method. Strength, the shear strength and wood breaking rate of the CLT specimens were tested by the stair shear method. At the same time, the failure mode of the CLT board was analyzed. The main conclusions indicate that the test values of bending and shear performance of Hemlock CLT can meet the relevant grade requirements of standard ANSI APA PRG320: 2012. During the bending process, the CLT specimen firstly exhibits a rolling shear failure of vertical layer after reaching the non-elastic deformation phase. After that, the damage extends gradually to the interface layer. The final failure mode is shear failure of interface layer or tensile failure of parallel layer. The interlaminar shear performance is partly relevant to the converted timber performance of parallel layer of CLT under the short-span three-point bending test conditions. The position of interlaminar shear failures is concentrated near support points of specimens and the position is generally located at the interface between parallel and vertical layers, inclining to…
The technical bark was used to obtain betulin; the one which is a barking of birch balance at pulp and paper production. The bark was prepared by grinding it on a crusher of abrasive action and fractionating, thus, the main fractions were obtained: less than 1 mm (35.4%), from 3 to 4.5 mm (31.5%). The bark was separated during the grinding process, the bark prevails in the coarse fraction, while bast is found in the fine fraction. For comparison, model samples of various sizes of birch bark were obtained by hand cutting. Chemical processing of bark fractions and model birch bark samples were carried out by the use of super-high frequencies (SHF) extraction with ethyl alcohol. Raw betulin was settled from extracts. The yield of extractive substances and raw betulin was 12.1-21.9% and 5.1-16.7% from absolutely dry raw materials; the maximum yield was from a coarse fraction of the bark or from model samples with smaller particle sizes. The authors studied the kinetics of the yield of extractive substances depending on the duration of SHF-extraction for bark fractions and birch bark samples. The optimal duration of the extraction for bark fractions is 10 min, and for birch bark is 15…
A multi-stage cascade model was implemented on wood composite boards in four stages: particle boards → 100% recycling → middle density fibreboards → 100% recycling → paper liner. Preparation of composite boards bonded with urea-formaldehyde resin was simulated on plates 400 x 400 mm and final fiber was pulped using semi-production refiners to create the conditions closed to real. Mass changes and losses were observed during a whole simulated life process. Results confirmed a deterioration of mechanical strength of recycled particle boards, the flexural strength in 13% and internal bond strength in 34% and slight increasing of the modulus of elasticity in static bending in 1.3%. Termomechanical pulping for the fineness in range 13°SR-24°SR (Schopper-Riegler) was chosen as appropriate for a fibrous board preparation from recycled chips, but their mechanical properties are at lowest levels compared to the requirements of standards. A low quality paper liner containing OCC, to improve its strength, was produced in the last stage of cascading.
Cork is the outer bark of the cork oak (Quercus suber L.), it is a secondary protection structure of tree, and its chemical composition is different from that of other lignocellulosic materials, as wood, agricultural, or forestry wastes. The best cork sheets are used to manufacture natural cork stoppers, vital in the aging process of “great” wines. It is a Mediterranean species covering an overall area of 2,139,942 hectares; Portugal and Spain countries where it occupies a larger area. This paper was developed to assess the possibility of implementing a system of payment for ecosystem services and/or a certification of forest management for small stands of cork oak privately owned areas of less than 25 hectares. The process is leaded by the Regional Groups of Forest Certification and Chain of Custody, main regional institutions. The system used is the Programme for the Endorsement of Forest Certification (PEFC). As specified by the multifunctional forestry applied in these ecosystems, its main use is the production of natural cork stoppers for the quality aging wines. The cork oak forests are living representatives of sustainability and a driving force of sustainable development.
WOOD RESEARCH Volume 65, Number 6
The hydrothermal treatment of maple (Acer pseudoplatanus L.) wood by steam represents the modification method with the effective heat transfer, which can improve industrially significant properties of wood, i.e. its color, hydrophobicity and subsequently dimensional stability. The maple wood was modified by steam at 125°C during 8 hours, and at pressure of 0.18 MPa. The water contact angle of steam-treated maple wood increased from 44.9° (for untreated maple wood) to 55.3° (for steam-treated maple wood), and the stability of water drop on steam-treated maple wood surface increased. FTIR spectra show an increase in C=O and glycoside bonds concentration on the surface of steam-treated maple wood, but the concentration of C-O-C groups decreased. SEM micro photos confirmed the deformation and shrinking of maple wood cells due to steam treatment. XPS measurements confirmed, that the concentration of oxygen as well as C=O and C-O-O groups on the surface of steam-treated maple wood showed a slight decrease in comparison with pristine wood sample.
Vacuum heat treatment was used to improve the dimensional stability of Toona sinensis wood in this study, the shrinking and swelling rates, the physical-mechanical properties, and the chemical compositions before and after the thermal treatment were evaluated. The results revealed that the volume shrinkage and swelling rate for the heat-treated wood samples were decreased by 45.60% and 49.95%, respectively at 220°C for 6 h indicating that thermal treatment could obviously improve the dimensional stability of Toona sinensis wood. Thermal treatment also decreased the mechanical strength. The surface color was changed by the treatment. The chemical composition results showed the decrease in density and mechanical strength was due to the partial degradation of hemicellulose during the treatment. The results of this study that vacuum heat treatment could improve the dimensional stability by sacrificing somewhat mechanical strength, the treatment conditions mainly the temperature should be properly controlled to archive an optimized improvement in dimensional stability with minimum reduction in mechanical strength.
Poplar (Populus x euramericana cv. pannonia) samples were irradiated using ultraviolet light emitter mercury lamp. Other series of specimens were treated with the combination of UV radiation and water leaching. The total duration of UV radiation for both series of specimens was 20 days. The total duration of water leaching was 10 days. One cycle of the combined treatment consisted of 2-day UV radiation followed by one day water leaching. The IR measurement was carried out after both UV radiation and water leaching to monitor both effects separately. Lignin degradation of water leached samples was found to be greater than that of the solely UV treated samples. The guaiacyl and the syringyl lignin showed similar degradation properties. The unconjugated carbonyl groups generated by the photodegradation proved to be the most sensitive chemical components to leaching. As a consequence of photodegradation, two absorption bands of unconjugated carbonyl groups were grown up at 1715 and 1759 cm-1 wavenumbers. The band at 1759 cm-1 was much more sensitive to water leaching than the band at 1715 cm-1. Ten days of water leaching was long enough to remove all unconjugated carbonyls generated by the photodegradation. The water was able to leach out carbonyl groups…
The Fischer-Tropsch process is a chemical reaction that enables liquid hydrocarbons to be produced from coal, natural gas, or biomass (e.g. wood). The heat of combustion and effective heat of combustion are important data for fuel used to produce energy. The usefulness of a particular fuel for society is usually evaluated on the basis of the energy returned versus the energy invested (EROI) = energy recovered/energy invested. The subject of the research was the product of a Fischer-Tropsch synthesis from a synthesis gas, which was produced through the liquefaction of sawdust from spruce wood. The synthesis took place in the reactor FIX BED at a temperature of 220 to 350°C and a pressure of 2 to 3 MPa (the hydrogen to carbon monoxide ratio was approximately 2:1). The Fischer-Tropsch fuel that was produced had a heat of combustion of 27.79 M.kg-1, effective heat of combustion 25.14 M.kg-1 and an EROI coefficient of 2.39.
The paper is focused on the effect of freezing and cyclic freezing-thawing pretreatment of poplar sapwood (Populus alba L.). The experimental comparison was carried out by the sawdust fraction 0.7 mm as (a) water-saturated and (b) dry. Monosaccharide yields, as well as an amount of acetic acid, were measured after 6, 24, 48, 72, and 96 hours of enzymatic hydrolysis with 15% load of the enzyme measured to total cellulose content. The influence of freezing rate on total yields was observed on equally prepared samples with different weights (31 g, 25 g, 62.5 g, 125 g, 250 g, 500 g, and 1000 g) by "cubic" tests. To increase the efficiency of pretreatment, a cyclic freezing-thawing experiment at temperatures -20°C and +25°C was performed. The results show that single freezing of grounded poplar sapwood impregnated by water or dry in its matter is not a sufficient pretreatment method, so cyclic freeze-thaw is needed to enhance the yield of monosaccharides. Analysis of cubic test showed that slower freezing process has a positive effect on enzyme accessibility.
The subject of the article is to monitor the changes of moisture on the contact surface concrete and timber part of the composite timber-concrete beam. The moisture directly affects the properties of timber and causes its volume changes and degradation processes. These effects reduce of durability and load capacity of the structures. The beam was placed at the exterior. The observed contacts of the beam are often critical on real structures, as it is difficult to repair and maintenance in the case of increasing moisture or intrusion of dirt. The experiment was used to monitor and evaluate the dependence of changing moisture in contacts depending on ambient environmental conditions.
A total of forty-eight specimens were tested, including forty short timber columns at elevated temperatures and eight short timber columns left untreated at ambient temperature. The main parameters explored in the test include column heights (135, 180, 225 and 270 mm), elevated temperature duration (10, 20, 30, 40 and 50 min) and section form. It was found that two new failure modes were generated after the specimens exposed to the elevated temperatures: splitting failure and bottom crushing, and the ultimate bearing capacity of the specimens with bottom crushing is the lowest. The ductility of circular specimens increases with the increases of column height. When the elevated temperature duration reaches 50 min, the plasticity of the specimens basically subside. The ultimate bearing capacity of the timber columns decreases with the increase of the elevated temperature duration and the maximum reduction is about 60% percent.
This study aimed to determine the influence of the stand age and selected weather conditions on the cambial activity, xylem and phloem formation and their development. For the analysis, microcores were taken weekly from two corresponding stands of Norway spruce (Picea abies (L.) Karst.) with various ages (35- and 106-years-old) during the growing season 2012 in the Czech Republic. Young specimens were characterised by higher cambium activity; however, more considerable variation and imbalance were found there. In old trees, delayed processes during the development of the xylem and phloem at the cell level were proved. The cambium activity started in March till mid-April, and it lasted for 22 weeks in both cases. The commencement of xylogenesis was established in the first half of May. In both investigated stands, the fully lignified ring was observed at the end of October. For the creation of most xylem cells, it was required 124 and 121 days in the young and old stands, respectively. Daily increment of 0.57 (young) and 0.49 (old) cells on average was observed during the active xylem growth. The relationship between air temperature and wood cell formation for both age groups was recorded. The precipitation influenced wood development just in…
The wood chipping system in a disc chipper Carthage-Norman was studied. The study showed many operational problems related to obtaining chips of different length in the process of wood chipping. Excessive amount of fines and pin fractions were produced in the chipper. The reason for this was the too high cutting speed of the logs and the wrong clearance angle in the chipper. The actual and optimal distribution of the cutting velocity occurring on the chipper knife was determined using the Matlab/Simulink model. In addition, optimal clearance angles in the chipper were determined using the model.
In order to improve dimensional stability and control deformation, heat treatment (HT) and wax impregnation (WI) were conducted to large size boards (LB) of Pterocarpus macrocarpus and the tangential swelling were compared in various relative humidity (RH) conditions. The results show that the tangential swelling and shrinking of control group and treated group performed differently corresponded to various relative humidity (RH). Comparing with control group, the swelling ratio of HT combined WI group was much less, and followed by 180°C-3h HT group. The maximum swelling ratio decreased by 31% and 29% in humidity chamber and indoor conditions respectively. The swelling ratio was affected by size of samples, LB showed smaller welling ratio than small sample. Wax filled in cell cavities and presented uneven distributions after impregnation. The rate of wood hygroscopicity was reduced after HT combined WI treatment which was an effective method on improvement of wood dimensional stability.
Bending moment resistances of L-shaped furniture frame joints under tension and compression loadings
Effect of wood species, joint techniques, and adhesive type on bending moment resistances were investigated. 480 L-shaped joint specimens were tested including 2 loadings, 4 wood species, 3 joint techniques, 2 adhesives, and 10 replications. Specimens were prepared from Scotch pine, Oriental beech, oak, and chestnut. The joint techniques were dowel, half lap and open mortise and tenon, and type of adhesives were polyvinyl acetate (PVAc) and polyurethane (PU). Bending moment resistance of the joints under compression ranged from a low of 60 Nm for Scotch pine dowel joints with PVAc to oak half lap joints a high of 281 N.m w/PVAc. Bending moment resistance of the joints loaded in tension ranged from a low of 230 N.m for scotch pine dowel joints w/PVAc and to a maximum of 917 N.m for oak half lap joints w/PVAc. Highest average moment resistance was achieved with oak half lap jointed specimens w/PVAc, under both loadings.
High performance bamboo-based composite panel taking bamboo mats, bamboo curtains and poplar veneers are used as raw material, is manufactured from the each layers slab was crisscrossed, impregnated with phenolic resin, compressed and cured. The product was optimized by Box-Behnken model design and data analysis. The results show that the best parameter conditions were hot pressing temperature of 140°C, hot pressing time of 94 s.mm-1, and hot pressing pressure of 2.5 MPa. The model was validated according to the optimal process parameters and the static bending strength (MOR), elastic modulus (MOE), thickness expansion rate of water absorbing, adhesive strength and density are 98.95 MPa, 8.81 GPa, 4.7%, 1.25 MPa, 0.89 g.cm-3, respectively. The actual value is close to the predicted value, confirming that the obtained model can accurately predict the MOR of the product using the three factors of hot pressing as variables under different conditions.
The influence of tree species on basic density of wood, bark and small-wood was investigated here. Experimental material was obtained from 73 trees of 7 tree species, namely alder (Alnus glutinosa (L.) Gaertn.), beech (Fagus sylvatica L.), birch (Betula pendula Roth.), hornbeam (Carpinus betulus L.), Black locust (Robinia pseudoacacia L.), Sessile oak (Quercus petraea (Matt.) Liebl.) and Turkey oak (Quercus cerris L.) from the territory of Slovakia. Wood and bark samples were taken from discs cut from three trunk sections and from small-wood and branch parts coming from tree crowns. The volume of green samples was measured in graduated cylinders with a precision of 1 ml; a dry matter was measured with a precision of 0.01 g. The statistically significant effect has been shown in tree species, biomass fractions and locations on the tree. The average basic density of all species varies from 440 to 650 kg.m-3 for wood, for bark it is 380-670 kg.m-3 and for small-wood outside bark it reaches 490-650 kg.m-3. Alder and Black locust tree species have the lowest and highest wood density, Black locust and Turkey oak of bark and alder and Turkey oak of small-wood.
In this work, statistical modeling and optimization of hydrolyzate from Ampelodesmos mauritanicus (Diss) using 1.5% sulfuric acid hydrolysis was carried. A central composite design (CCD) model was used to study the influence of reaction temperature (70°C to 110°C), ratio (5% to 15%, w/v), and reaction time (60 to 180 min). Reducing sugars, pH, proteins, lignin, ash content and the elements minerals composition were determined. Optimized reducing sugars yield of 0.249 g.g-1 of dry weight was obtained for reaction time of 180 min, reaction temperature of 110°C and ratio 5% (w/v). Therefore, this study tests the production of bioethanol from pure Diss hydrolyzate by the yeast Saccharomyces cerevisiae ATCC 9763. This strain showed a consumption of 67.6% of reducing sugars available (25 g.L-1), which made it possible to obtain ethanol yield per consumed sugar 0.33 g.g-1.
This paper is a first study to evaluate the acoustical performance of virgin cork environmentally friendly by-product of the cork that can be used inside dwellings. To obtain the acoustical performance of the virgin cork, previously, it was properly treated and flattened into slabs, and later compared to commercial rock wool. The results obtained showed that this material, specially treated and added in some building system, could show good acoustic properties with a certain broadband absorption spectrum.
Volume 64 (2019)
WOOD RESEARCH Volume 64, Number 1
The objective of this study was to investigate the color and surface chemical properties of Eucalyptus pellita wood subjected to thermo-vacuum treatment. Specimens were thermally modified in a vacuum at various temperatures for 4 h. The color parameters of untreated and heattreated samples were measured using the CIE Lab method. Surface chemical properties were evaluated by UV-Vis spectroscopy, 13C NMR spectroscopy and X-ray photoelectron spectroscopy. The results showed that eucalypt wood became darker uniformly throughout with the increase of treatment temperature, and the total color variation ΔE* obviously increased at higher temperature. The spectral changes indicated that degradation and oxidation of hemicellulose, lignin and extractives contributed to the formation of color substances during thermo-vacuum treatment. Crystalline content of carbohydrates increased. The decrease in O/C ratio signified the increase of the relative content of lignin and extractives on the wood surfaces in the heating process.
New requirements for the biofuels industry force individual enterprises to develop various procedures for newly selected substrates pretreatments that could be applicable in processing of large quantities of raw materials. Even greater pressures are on second-generation biofuels producers justified by selection of waste lignocellulosic substrates and methods of substrate processing. Among the most suitable lignocellulosic raw materials in Slovak Republic (SR) for 2G bioethanol production is wheat straw. This raw material (Senec region, SR) for enzymatic hydrolysis was pretreated by dry milling (Brabender), cyclic freezing and thawing, wet milling (Sprout Waldron), two-step process of steam explosion at 180°C and extrusion at 145°C and one-step process of steam explosion at different temperatures. Wheat straw holocellulose accessibility was tested by adsorption of three commercially available dyes (Pylam Products Company, Inc., USA). Absorptivity coefficient of each dye at its maximum wavelength was determined from individual calibration curves of dyes and their values resulted ranging from 13.78 to 19.52 dm3.g-1.cm-1. The absorption of solution was measured and concentration of residual dye was calculated at given wavelength. The accessibility of holocellulose contained in wheat straw pretreated by steam explosion was controlled by SEM (scanning electron microscope) in correlation with the ratio of adsorbed dyes according…
The goal of this research was to investigate the effect of thermal treatment on mechanical properties and surface characteristic of rubberwood (Hevea brasiliensis) and find the mathematical model to predict the mechanical properties used by its surface characteristic. Rubberwood specimens were treated by steaming at five different temperature levels of 170, 185, 200, 215, and 230°C for two different durations of 1.5 and 3 h. Based on the results, the values of bending strength, modulus of elasticity, compression strength and impact bending decreased, and the glossiness and chromatic aberration (∆E) increased with increasing temperature and enlarging duration further. This study revealed that chromaticity parameters b*, ∆E and the gloss of perpendicular to grain (GZT) could evaluate the mechanical properties of thermally-modified wood to achieve the mechanical properties detection without destruction.
This study was designed to investigate some surface characteristics such as glossiness and surface roughness changes of varnished thermowood after six months of weathering. Thermal modification of Scots pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis L.) wood were carried out by hot air in an oven for 1, 2, and 3 hours at 205, 215, and 225°C. After the modification process, wood specimens were varnished using a polyurethane varnish (PV) and cellulosic varnish (CV). The natural weathering process caused an increase in the surface roughness of the test specimens according to the test results. The Scots pine and Oriental beech test specimens which were heat treated and varnished gave more favorable results compared to only varnish test specimens after natural weathering in terms of surface characteristics such as surface roughness and glossiness. Generally, as the heat treatment time and temperature increase, it is observed that the surface characteristics of the Scots pine and Oriental beech wood specimens improve positively. According to the results of the tests, the samples varnished with polyurethane varnish gave better results in terms of surface roughness at the end of the natural weathering process, whereas the samples varnished with cellulosic varnish gave better results…
Chemical composition and susceptibility to delignification by neutral sulfate liquor of Miscanthus giganteus stems and of birch wood were compared. The yield of pulping as well as degree and selectivity of delignification were tested in various technological conditions (cooking time, hydro module, alkali charge). Having a similar chemical composition, Miscanthus giganteus stems are subjected to quicker and deeper delignification with neutral sulfite liquor than birch wood. This phenomenon is probably associated with differences in the qualitative composition of lignin, distribution of lignin in the cell walls and in the morphological features of both raw materials.
This study examines the combustion properties of Scots pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis L.) in 3 stages (CWF, SC and EC) according to ASTM E 160-50 (1975). Wood samples were impregnated with Tanalith-E (T) and Wolmanit-CB (WC) and then were varnished with Synthetic (St) and water based (wb) varnishes. When the combustion was completed, the weight loss, combustion temperatures, illuminance values, total time of combustion, and demolition time were measured. As the result, illuminance value of Oriental beech wood decreased, while the smoke density increased. Scots pine was later destroyed in the combustion process. Areas with a risk of fire are advised to use pine wood instead of beech. Wolmanit-CB and synthetic varnish reduced the temperature and illuminance values. Oriental beech, Tanalith-E, and synthetic varnish resulted in the highest temperatures for all combustion stages. This triple interaction increased total combustion time values by more than 90% when compared with the control samples.
This study determines the main energy characteristics of wood and charcoal within five tree species of the forest of Ixtlán de Juárez, Oaxaca, México: Alnus acuminata, Arbutus xalapensis, Myrsine juergensenii, Persea longipes and Prunus serotina. Basic density, moisture content, charcoal yield, volatile material, ash content, high heating value, fixed carbon and fuel value index were determined for each one. The average results of the species are in the range of 0.372 to 0.498 g. cm-3 for wood density; 26.19 to 34.12% for charcoal yield; 77.29 to 83.66% for wood volatile matter and 28.40 to 34.25% for charcoal volatile matter; 0.56 to 1.50% for wood ash and 1.13 to 4.83% for charcoal; 19.50 to 24.99 MJ. kg-1 for high heating value of wood and 29.38 to 32.11 MJ. kg-1 for charcoal. It was determined that these species provide a good alternative for burning wood and charcoal. Additionally, these remain untapped resources in the Sierra Juárez region, meaning that awareness and inclusion in management plans could be of relative importance to the development of the forestry sector.
This work aimed to study mineralization and detoxification of BDE209 by biomimetic oxidation. The removal rate (RR) of BDE209 of process was comparatively investigated in the presence of UV radiation using immobilized Cu([H4]salen) complexes (Cu([H4]salen)/IM and Cu([H4]salen)/SB) as biomimetic catalysts. Their neat and [H2]salen complexes were compared towards BDE209 degradation. UV effects were evaluated according to RR. Ecotoxicities were measured for treated BDE209 solutions and explained in terms of total organic carbon (TOC). The results showed that UV-Cu([H4]salen)/SB process evidently gave high RR and low ecotoxicity in BDE209 degradation, indicating a significant superiority of biomimetic catalysis, complex reduction and immobilization and UV radiation.
To investigate the changes of microstructure and dimensional stability during hydrothermal treatment, the Chinese sweetgum (Liquidambar formosana Hance) wood samples were treated in a numerical show constant temperature water bath with temperature of 60, 80 and 100°C for 4 h. The dry shrinkage rate and water absorption of untreated and treated samples were measured. Scanning electron microscopy (SEM) was selected to observe and investigate the changes of wood microstructure, which caused by hydrothermal treatment. The results showed that dry shrinkage rate increased from 4.92% to 7.00% and 9.62% to 10.12% in tangential direction and radial direction, respectively. However, the shrinkage rate difference (SRD) as an index to evaluate possibility of wood deformation, decreased from 1.96 to 1.45, which meant the shape stability of treated samples improved. The water absorption increased from 93.15% to 112.11%. From the results of SEM, the most sediment on aspirated pits were removed and pit membrane was ruptured after treatment. It had positive effect on moisture migration and wood permeability. It is maybe the reason of the variation of water absorption and dry shrinkage rate.
Adhesives made from lignin are one of the most promising alternatives to common ureaformaldehyde adhesives. One of the possible sources is from wood or bark liquefaction at low temperatures and pressure. The possibility of using forest wastes for the production of adhesives was the objective of this work. Eucalypt bark and branches are wastes produced in the company Pedrosa & Irmãos, which is a forest management company based in Portugal (Leiria). The wastes were liquefied with polyalcohols catalyzed by sulfuric acid. The water insoluble fraction of the liquefied material was used for the production of the bio-adhesive. Both fractions were characterized and the bonding performance of the bio-adhesive was tested by ABES. The bio-adhesives obtained from bark or branches were similar, exhibiting a bonding strength approximately half of the conventional UF resin.
Wood is integral to the construction industry despite the fact that it is a highly flammable material. Due to thermal stress, it is subject to the process of pyrolysis. However, not every type of wood burns the same. This dissimilarity is caused by the changes in its internal structure. Flammability rate of tree species can be modified by means of thermal modification, i.e. change in its internal structure or by using coating compositions which form a fire-protecting layer on its surface. The paper comprises a testing and an evaluation of iroko wood which is predominantly used as floor covering and cladding material for building structures. The authors focus on determining the connection between the structure of this exotic tree type and the eventual thermal degradation (burning course, significant changes, amount of material burnt, etc.) of the samples. Small size samples were used during laboratory measurements. Their width and thickness were approximately the same as for commonly used cladding boards. The data obtained in the laboratory have been processed, transformed into evaluation criteria and connected with theoretical knowledge, creating an overview of its eventual flammability. Laboratory test results prove low flammability rate of test samples. Mass loss was an important criterion.…
In this study, forced convective drying process of wood material with rectangular shape was investigated. Firstly, governing equations for the flow field were solved by using ANSYS Fluent. Then average heat transfer coefficient on the surface was calculated by using Standard k-ɛ Turbulence Model. It was found that mass transfer coefficient making use of the relationship between heat and mass transfer. Simultaneous heat and mass transfer equations were solved transiently with Comsol Multiphysics using surface boundary conditions for selected air velocity, air temperature and material thickness. In drying process the moisture and temperature distributions inside the solid were obtained transiently. The mathematical model for equations was formed using Fourier heat and Fick diffusion models. Results acquired from the present model were compared with a study results which are available in literature and it was shown a very good agreement.
This paper used fast-growing eucalyptus wood to prepare three shelf structures as solid wood puzzle, frame panels, and flat puzzle plus metal wear belt, respectively, and then, a creep tests was examined. After fitting the examined results by Burgers creep model, the long-term creep tendency was predicted from the short-term creep behavior of the three structures. Based on the Burgers creep model analysis, an optimized structure that can alleviate the bending problem on bookcase shelf was obtained. The results also provide practical reference for fast-growing eucalyptus wood for furniture design. During comparative analysis of the bending creep and strain, the results show that the flexural creep properties of frame panel and flat puzzle plus metal wear belt were superior to those of solid wood puzzle. After considering the aesthetics, frame panel was the best structure. Furthermore, the fitting results show that using the Burgers model to analyze the creep process of furniture is a very effective method and has strong theoretical and practical significance.
The objective of this study was to improve physical and mechanical properties of fast-growing Chinese white poplar wood (Populus tomentosa Carrière). To this purpose, the heat treatment and impregnation by sodium silicate solution were investigated. In experiments, four processes under four different conditions were applied on poplar wood samples: temperature treatment (T), solution treatment (J), first solution and then temperature treatment (J-T) and first temperature and then solution treatment (T-J). The results showed that all measured mechanical properties were improved under conditions of J process. The hardness, impact toughness, bending strength and modulus of elasticity were improved by 8.4%, 29.2%, 12.0% and 16.1%, respectively. Additionally, tested wood samples exhibited significant increasing of values some mechanical properties such as hardness (70.1%) and modulus of elasticity (80.4%) in comparison with values for untreated samples if treatment was conducted under J-T process conditions. Treated wood by this technology could be utilized as solid wood composite or material for flooring substrate.
Spruce and Douglas fir are the main materials of today’s modern wooden structure buildings. In wooden structure buildings, holes often have to be created on the building components in order to reserve channels for pipelines. At present, there are no detailed studies regarding the mechanical properties of these two kinds of lumber under open-hole condition. In this paper, universal mechanical testing machine was utilized to perform three-point bending tests on small samples of spruce and Douglas fir with open-hole (opening diameters being Ø13, Ø16, Ø20 respectively) and without open-hole. The bending strength and modulus of elasticity of openhole and no open-hole samples were compared, the effects of hole sizes on samples mechanical properties were analyzed and discussed, and the samples’ failure patterns and failure mechanisms were also studied. The experiments were loaded at a constant speed 5 mm. min-1 until the sample was broken, with the loading time controlled within 2 - 3 minutes. The results showed that: open-hole had significant impact on the bending strength of both kinds of lumber. In terms of failure modes, most of the Douglas fir samples were deformed only at the compression point before failing, while the Spruce samples not only formed grooves at…
In this experiment, cocobolo (Dalbergia retusa Hesml.) and African padauk (Pterocarpus soyauxii) specimen were selected before treating with wax, wax + 20% dimethyl silicone oil, wax + 40% dimethyl silicone oil at 120°C for 3 h and 6 h respectively. The weight gain percentage (WPG), radial swelling coefficients (RS), tangential swelling coefficients (TS), chemical composition and strength of hydroxyl groups were investigated. The results indicated that three factors affect dimensional stability, including the impregnation time, tree species and ratio of wax /dimethyl silicone oil. The degree of a melioration in the dimensional stability increase as the impregnation time increase from 3h to 6h. The effect of the impregnation on the dimensional stability of the African padauk was better than that of the cocobolo. Wax+ 40% dimethylsilicone oil was the optimal condition in this study. Wax and dimethylsilicone oil mixed impregnation can improve the dimensional stability to a certain extent, which provides a new idea for the wood modification.
Smoke drying by means of a direct-fired kiln is considered to be one of the most cost-effective methods of drying lumber. In the present study, Siberian larch (Larix sibirica) lumber was dried using a direct-fired kiln developed in Mongolia. When approximately 500 kg of sawdust was used as fuel, the maximum and mean temperatures in the kiln were 78.2°C and 54.2°C for the lower side, respectively, while they were 70.4°C and 50.1°C for the upper side, respectively. The temperature inside the kiln was above 60°C for a duration of about 40 to 50 hours. The moisture content of the lumber decreased from 56.4% to 23.2%. No significant differences in terms of the mechanical properties were found between air- and smoke-dried wood. Based on these results it appears that the direct-fired kiln developed in Mongolia is useful for the low-cost drying of Siberian larch lumber, although improvements to the kiln and a prolonged drying schedule are needed in order to obtain more dried lumber.
WOOD RESEARCH Volume 64, Number 2
This study focuses on manufacturing of medium density fibreboard (MDF) panels bonded with dextrin-based wood adhesive and crosslinked in situ with various weight ratios of synthetic (e.g., polymeric-methane diphenyl-diisocyanate, pMDI) or bio-based (e.g., glyoxal) crosslinkers. The physical and mechanical properties of the panels were evaluated and compared with those from panels without crosslinker (control). Modulus of rupture (MOR) and internal bond (IB) strength of the MDF panels were considerably increased by increasing the crosslinkers’ content. While, slight improvements were observed in modulus of elasticity (MOE) of the panels as a function of crosslinker type and content. Addition of crosslinkers clearly reduced the thickness swelling (TS) and water absorption (WA) of the panels, whereas, the panels with pMDI showed superior performances than the control and glyoxal added ones within 4 h and 24 h immersion in water. The results indicate the potential of dextrin as wood panel adhesive along with the use of appropriate crosslinkers.
Palmyra palm (Borassus aethiopum Mart.) is a large palm tree whose wood is often used for its mechanical resistance and weathering in buildings in Africa. In this work, the influence of fibre characteristics on the mechanical properties of wood was studied. For this purpose, the mechanical characteristics were determined and study of the micrograph of the sapwood and Duramen which are the useful parts of this wood were carried out. The results of this study show the mechanical properties of the palmyra are very influenced by the number and the mechanical characteristics of the fibres. The proposed polynomial model of the evolution of the mechanical characteristics gives the good results because the maximum relative mistakes of the prevision are 4.43% for the breaking strength and 0.40% for the Young’s modulus.
Experimental material was obtained from 43 trees of four tree species, namely pine, fir, larch and spruce from the territory of Slovakia. Wood and bark samples were taken from the discs in three locations on a stem and from small-wood, branches coming from tree crowns. The volume of fresh samples was measured in calibrated graduated cylinders with a precision of 1 ml; a dry matter was measured with a precision of 0.01 g. The statistically significant effect has been shown in tree species, fractions of biomass and locations on the tree using a special software based on ANOVA. The average basic density of wood for all species ranges from 373 to 508 kg. m-3. For bark it is 333-551 kg. m-3 and for small-wood outside bark it reaches 406-535 kg. m-3. The fir and larch have the lowest and highest values for wood density; pine and fir for bark density and pine and spruce species for small-wood density.
Evaluation of horizontal shear performance of larch CLT walls according to the edge connection shape
In this study, cyclic tests were performed on the larch CLT shear walls depending on the half lap reinforcement of half-lap connections and reinforced plywood of spline connections in order to evaluate the horizontal shear performance of the larch CLT walls. The test results show that there is no difference in residual strength depending on the reinforcement of half-lap connection, but their initial stiffness has been increased by 9%. There was no significant difference either in the residual strength of double spline connections depending on the application of reinforced plywood, while the spline reinforcement has failed to increase initial stiffness. All of the larch CLT walls constructed according to the edge connection shape were measured to have a strength reduction ratio of less than 10% in each horizontal displacement intervals and an equivalent viscous damping ratio of less than 10% for energy dissipation in the initial and final horizontal displacement intervals, thereby confirming that their excellent horizontal shear performance and seismic performance.
Four specimens of a thin-walled square steel tube/bamboo plywood composite hollow column with binding bars (SBCCB) were each subjected to an axial compressive creep test and a subsequent axial compression test to examine their axial compressive creep behavior and post-creep compressive failure modes as well as to analyze the effects of long-term loading on the ultimate axial compression-bearing capacity of the SBCCB. The results show that the axial compressive creep strain decreased with increasing slenderness ratio and increased with increasing axial compressive stress. The creep–time curves of the specimens with various slenderness ratios all exhibited a transient creep stage and a steady-stage stage. Temperature and humidity variations affected local creep behavior. Creep significantly affected the axial compression-bearing capacity as well as the axial and lateral deformability of the SBCCB. The rheological mechanics-based Burgers model can well predict the creep strain development of the SBCCB.
This study was designed to determine some selected parameters such as gloss, surface roughness, and color changes of Scots pine wood impregnated with commonly used fireretardant (FR) chemicals after UV irradiance. Sodium acetate (SA), ammonium chlorite (AC), zinc chlorite (ZC), ammoniumsulphate (AS), and di ammonium phosphate (DAP) were used as fire retardants. Wood specimens were prepared from Scots pine (Pinus sylvestris L.). Before test, wood specimens were impregnated with 5 % aqueous solution of chemicals according to ASTM D 1413-76 standard. Results showed that UV irradiance caused gloss loss and increase surface roughness of FR impregnated and un-treated (control) Scots pine specimen. DAP was the most effective chemical in terms of reducing gloss loss and surface roughness of Scots pine after 750 h UV irradiance exposure. UV irradiance caused a dark, reddish, and yellowish color of impregnated and un-treated (control) Scots pine specimen after all UV irradiance periods. Total color changes in color (∆E*) exhibited a systematic trend to higher values with increasing UV irradiance time. Total color changes of ZC impregnated Scots pine were the lowest after 750 h UV irradiance exposure.
Ultimate compression strength parallel to grain (UCS) of wood is one of important performance to evaluate the structural security of old wood buildings. Poplar wood (Populus tomentosa Carrière), Chinese larch wood (Larix gmelinii (Rupr.) Kuzen.) and Chinese fir wood (Cunninghamia lanceolata (Lamb.) Hook) were selected as the models in this paper. The aim of study is to predict UCS of wood by using resistograph and screw withdrawal methods. Compared with the screw withdrawal method (SW), resistograph method (RM) is generally more reliable, but because of the expenses involved, SW should also be considered as a much cheaper alternative. The results showed that the correlation coefficient between the RM and the UCS ranged from 0.5 to 0.7. The correlation coefficient between the double-start thread screw withdrawal force (SWDST) and the UCS distributed from 0.1 to 0.65, while the values of coefficients for the singlestart thread screw withdrawal (SWSST) differed from 0.4 to 0.65. In screw withdrawal method, greater pitch of screw resulted in higher correlation coefficient.
The influence of porosity, relative bonded area and air permeability on water absorption of unbeaten and beaten bleached kraft pulps from different wood species used for tissue paper production was investigated. The water absorption was determined by four different methods such as absorption of water after immersion, initial water absorption, water absorption capacity and saturation rate with water. Linear dependences between water absorption parameters and the structural parameters of individual pulps as well as all tested pulps were obtained. The correlation coefficients obtained within individual bleached kraft pulps were from 0.95 to 1.00 and within the whole group of pulps were from 0.86 to 0.98. Relative bonded area and air permeability were found to be the most suitable parameters for predicting of initial water absorption and saturation rate with water.
This article investigated properties of different lignocellulosic biomasses. Both acidified and non-acidified sodium chlorite were used to treat wood chips and sugar cane bagasse. Images were part of characterizations that included X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). Interestingly the results indicated that biomasses followed the similar crystallinity trend while thermal stability and functional groups on the cellulose surface seemed to differ. All the FT-IR spectra showed 8 main peaks but spectra of bagasse have an additional peak. Stretching vibrations of the O-Hand the C-H stretching group in cellulose molecules were clear for all biomasses. The treatment clearly removed most of aromatic compounds normally attributed to lignin and hemicellulose.
In this paper we compare the anatomical features (number of fibrous elements in the pulp unit, fiber length, diameter of fibers and lumens, coefficients of slenderness, flexibility and the Runkel coefficient) of both Miscanthus giganteus and birch wood. The raw materials were tested prior to pulping, after pulping and after refining. Comparisons of defibering ability and selected strength properties (CMT, SCT, tear resistance, burst) allowed evaluating the papermaking potential of neutral sulfite pulps obtained from the above-mentioned raw materials.
This study aimed to determine the effects of alkaline solvent treatment on the physical properties of cork, and to analysis the filtrate components of cork after cooking treatment. Potassium hydroxide (KOH), alkaline hydrogen peroxide (AHP), and ammonium hydroxide (AOH) were used as solvents. The properties of treated cork including color, volume, hardness, compression resilience ratio, and filtrate components of different solvent treatments were investigated. The results showed an increase in the cork’s volume, changes in color, and decrease in lightness after three solvent treatments. Hardness and compression resilience decreased after three solvents cooking, and the difference in the compression resilience ratio between 15 min and 24 h was at a minimum when cork was cooked in KOH solvent. The analyses of filtrate components after KOH and AHP cooking treatments indicated that the hemicelluloses content was generally higher than lignin content. Moreover, water-soluble lignin, obtained from the three solvent filtrates, consisted of a small amount of monosaccharides, such as arabinan, galactan, glucan, and xylan. Nuclear magnetism (NMR) spectra analysis demonstrated that the lignin in KOH and AOH filtrates consisted of G units and H units, while S units only appeared in KOHimmersed lignin. This study shows that solvent treatment changes cork’s…
Bark is much underutilized material. Most of the bark is used as fuel and for landscaping but there are still significant amounts of unused bark, hence creating a problem when disposed. Due to the aspects like colour, shape/size and ratio, and mechanical properties, bark is not a desired constituent for particleboard production. One of the possible uses of bark is related to its chemical compositions, specifically due to the phenolic-like components, bark can be used as formaldehyde scavenger.The aim of the paper is to present the usability of bark as particleboard formaldehyde scavenger. Single-layer particleboard made from wood particles spruce (Picea abies) and pine (Pinus sp.) bark mixture using urea-formaldehyde and melamine-urea formaldehyde as resin were tested for formaldehyde release. The formaldehyde release was determined by the Perforator method (EN 12460-5), gas analysis (EN 12460-3) and Flask method (EN 717-3). The experiment showed that the presence of bark lowers the formaldehyde release.
Wooden activated carbon hollow fiber (WACHF) is successfully synthesized from liquefied rubber wood (Hevea brasiliensis) using H2O activation. The structures of WACHF are studied by scanning electron microscope (SEM), X-ray diffraction (XRD) and N2 adsorption. The effects of activation temperature on methylene blue (MB) and iodine adsorption property were also studied. Results show that both wood hollow fiber (WHF) and WACHF have a smooth surface and hollow fibrous structure with an average hollowness of about 76.43%. With increased activation temperature, the graphite-like microcrystalline structure has been formed. In addition, WACHF has high Brunauer-Emmett-Teller (BET) surface area (1949 m2.g-1) and total pore volume (1.246 cm3.g-1), where the contribution for micropores is 47.4% and 46.3% for the mesopores. At 800°C, the MB adsorption and iodine adsorption of WACHF reach the maximal values of 412.6 mg. g-1 and 1123.7 mg. g-1, respectively. As a result, WACHF with double surface structures has great BET surface area and excellent adsorption property.
This article describes in detail the construction and operation of the test rig employed for experimental pulse-jet filtration of air polluted with small wood particles created during machining. It enables evaluation of filter media used for wood dust separation and examination of influence of filtration conditions on the filter performance. Exemplary results of some experiments were presented to illustrate research possibilities of the testing filter and the method. More detailed results of studies on the filtration mechanisms and key parameters which determine the performance of a filter will be presented in further papers.
This study was conducted to determine the lignin and sugars contents of yellow poplar (YP) sawdust immersed in tap water (TW), sulfuric acid (AC) and sodium hydroxide (AK) solutions. Klason lignin content of TW- and AC-immersed YP sawdust was higher than that of AK-immersed YP sawdust. Glucose showed the highest content among sugars extracted from YP sawdust. Durability of non-immersed YP pellets was the highest, followed by TW-, AC- and AK-immersed YP pellets. YP pellets became more durable by increasing the Klason lignin and xylose contents as well as decreasing the glucose content. Through microscopic observations and quantitative analysis of lignin distribution, lignin content on the surface of non-immersed YP pellets was higher than that of TW-, AC- and AK-immersed YP pellets. In conclusion, there are significant correlations between lignin or sugars contents of YP sawdust and fuel characteristics of wood pellets fabricated with the YP sawdust.
An analysis of accidents has shown that many fatal and serious accidents during woodworking result from kickback. This study assessed the influence of cutting conditions on hazards associated with kickback in milling wood materials. The research concerned the severity of hazards but not the probability of kickback. The speed of kickback was accepted as the quantitative measure of these hazards. An original method of kickback experimental testing on unique research test stand was applied. The speed of kickback was measured in different cutting conditions. The experiment involved controlled changes in cutting conditions, such as the type of cutting tool, cutting speed, machined material, and tool wear. Statistical analysis of the results verified some common opinions and ideas on the impact of basic cutting conditions on the hazards resulting from kickback during milling of wood materials. In some cases, the results of empirical testing did not confirm the commonplace opinions.
Rubberwood (Hevea brasiliensis) was thermal modified by hot pressing in an open system at three different temperatures (170, 185, 200°C) and two different durations (1.5, 3 h), and the effect on the physical and mechanical properties was studied. Results show that the thermal modification increased the oven-dried density and decreased the EMC (equilibrium moisture content) by 7.93% and 37.15%, respectively, and the dimensions stability was improved. Hardness, bending strength, modulus of bending and compressive strength parallel to grain of modified samples basically decreased with increasing temperature and time, but they showed a meaningful increase compared to control samples. However, impacting bending and nail withdrawal resistance decreased after hot pressing and thermal treatment, and the failure of the compensation for the impairment was the rubberwood hot pressed and thermal treated in the presence of air, and the participation of oxygen provoked rapid degradation reactions during the treatment.
WOOD RESEARCH Volume 64, Number 3
This work presents the results of an experimental investigation of the vibration response of cyclically loaded wood-based panels. The maximum temperature of the stationary state of the activation zone of samples of wood-based panels in the form of a rigid cantilever with their cyclic load at loading frequencies from 0 to 50 Hz and maximum internal stresses from 0.98 to 5.36 MPa was investigated. The purpose of this study is to determine the temperature of selfheating and to determine the dependence of the temperature on the loading conditions. The mathematical model is proposed in the form of system nonlinear ordinary differential equations, where stress, strain and temperature were used as the essential variables. The behaviour of the system is completely determined by the ratio of the introduced external energy and the value of the order parameter. The critical value of the order parameter depends on the thermo-physical properties of the material and is equal to the ratio of the value of the heat transfer coefficient multiplied by the area of thermal dispersion to the coefficient of linear thermal expansion.
The effect of a pressurized hot water treatment (PHWT) on the mechanical properties, chemical composition, surface color, and cellulose crystalline structure of Pine wood were examined in this study. The effects of PHWT of pine wood at 140, 160, 180, and 200°C for 1, 3 and 5 h were investigated in terms of changes in mechanical properties, chemical composition, surface color and cellulose crystallinity of pine wood by means of a GB/T standard, NREL LAP, Color Difference Meter, and X-ray diffraction (XRD). Both the temperature and treatment time showed significant effects. The results showed that the bending strength and elastic modulus decreased with an increasing temperature and duration. Changes in the chemical components and surface color occurred because of the degradation of the cellulose, hemicelluloses and lignin in the wood during the PHWT. Additionally, the relative degree of relative crystallinity of the samples increased. These findings demonstrated the potential of PHWT for the wood modification.
A sanding is a common woodworking operation to smooth the surface prior to apply surface finish or coating materials. All cutting processes damage the upper layer of wood surface and sanding also creates a deformation zone. This deformation zone is sensitive to artificial or environmental actions, especially to wetting. In order to determine the effect of wetting on the surface properties, to get insight into the dynamics of surface movement as a function of time during the wetting, special 3D surface roughness measurements were carried out and evaluated. For sanding of samples the most common grit sizes were selected and P100 and P180 sand papers were used. Measuring the weight of the samples the dynamics of evaporation of the applied water was also determined. The surface modification after wetting is caused by moisture gradients in the upper layer associated with swelling and shrinkage resulting in permanent deformations. For this layer the most characteristic roughness parameters are the average roughness Sa and the Abbott parameters Spk, Sk and Svk. The extent of roughness variation due to wetting is characterised by the ratio of roughness after wetting to the initial roughness value. The measurement results have shown that the simultaneous infiltration and…
Eucalyptus pellita is the fast-growing species which is being developed for a raw material of pulp and paper in Indonesia. The aim of this research was to evaluate the total phenolics (TPC) and flavanols contents (TFC) in the stemwood and bark parts from four individual trees. Another purpose was to determine its cell wall contents. Wood and bark materials in two vertical positions (bottom and top) were successively extracted using dichloromethane, ethanol and hot water as the solvents. Axial factor affected significantly in the values of hot water extract, TPC, and TFC but no significantly affected the cell wall component contents. The ethanol extract levels in the heartwood part was the significantly highest. It is noticed that the heartwood part had high levels of the TPC and TFC and low level in lignin content. From this experiment, the comparatively high levels of TPC and TFC in the heartwood indicate the potential antioxidative properties that should be explored in the future. Further, the low content of Klason lignin in the heartwood part would be an advantage for pulp production.
Zabelia biflora, a kind of broad-leaved shrub, with six distinct longitudinal furrows and petal-like structure in cross section, belongs to Zabelia and consists of sections interlaced with each other. It is meaningful to focus on the peculiar appearance of Zabelia biflora for the sake of outstanding structures. On the basis of quasi-static experiments of stretching, compression along the grain direction and bending in the tangential direction, dynamic experiments of the wood over its water contents ranging from 9% to 22% have been investigated using the split Hopkinson pressure bar. Combined with the electron scanning, 3D X-ray scanning reveals the microstructure of Zabelia biflora. Results show that the maximum bending force of this wood on the joint is higher than that of wood without the joint. Besides, although the static mechanical parameters of Zabelia biflora are basically the same order of magnitude compared with other hardwoods, the bending strength of the specimen with a joint is significantly improved by contrast with the wood possessing a similar density with it. In addition, it is been proved that there is a symmetrical and glass-like density distribution in the center of the wood. Meanwhile, the density presents a gradient-layer distribution from the up-down view.…
Beech wood is one of the most abundant species and the most harvested hardwood in Slovak Republic. The structure and chemical composition predetermines beech wood for the second generation bioethanol production. Steam explosion of beech wood from industrial treatment was investigated as a suitable pretreatment method. The effect of steam explosion temperature on beech sawdust enzymatic hydrolysis was investigated. Optimum steam explosion temperature at around 180°C was determined based on concentration of monosaccharides in hydrolysates and concentration of enzymatic hydrolysis inhibitors such as formic acid and acetic acid from beech sawdust. This corresponds to creating conditions resulting in good disintegration to the lignocellulosic structure which leads to increased cellulose accessibility. Non-treated beech sawdust does not enable sufficient cellulose accessibility while excessively high temperature results in significant breakdown of monosaccharides and lignin and formation of inhibitors. The concentration of inhibitors was also determined for each studied steam explosion temperature. Based on steam explosion of beech sawdust, the effect of severity factors was investigated to find the optimum conditions of steam explosion pretreatment on cellulose and xylan recovery of beech wood. The obtained optimum steam explosion temperature corresponds to severity factor R0 = 3.36 (180°C, 10 minutes).
In this study, the variation in the charring depth of wood studs inside wood-frame walls (WFWs) in a fire was investigated. First, the time variation in the surface temperature of wood studs inside WFWs was determined based on ISO 834 fire-resistance tests, and the resulting heating conditions were used in subsequent heat exposure tests. Then, wood stud specimens of four different wood species (Chinese fir, Japanese cedar, Southern pine and spruce) were each subjected to a heat exposure test in an electric furnace. The results exhibited no significant correlation between the charring depth of the wood stud specimens and the preheating density. In addition, the test data validated that the equation proposed by Sugahara can be used for predicting the charring depth of wood studs inside WFWs in a fire.
Volatile organic compounds (VOCs) have received a great deal of attention due to their high abundance during the drying process of wood particles. This is a potential environmental issue due to being low level ozone precursors. This work aimed to study the emissions of VOCs during drying in the particleboard manufacturing process. In this study, wood particles were dry and VOCs were collected using a sorption tube. The VOCs were analyzed with gas chromatographymass spectrometry to explore the effect of temperature on the composition of main components. The results indicated that α-pinene and D-limonene were the dominant components. The results also indicated that using natural gas or wood dust as a heat source did not have a major impact on the emission characteristics of VOCs.
The reliability analysis method was investigated in this study to obtain design values of ultimate compression strength parallel to grain (UCS) of Chinese larch visually-graded dimension lumber of common size. A total of 748 lumber samples of 40 by 90 mm were tested for static full-size compression strength according to Chinese National Standards’ requirements of the reliability index. The goodness of fit for the UCS distribution of four visual grades was analyzed and the first-order second-moment reliability analysis under different load cases was performed based on all the test data. The log-normal distribution was the optimizing fitted distribution of the compression strength of Chinese larch dimension lumber. Design values of the compression strength for grades Ic, IIc, IIIc and IVc were suggested for the minimum reliability index. These design values will be recommended to the standard committee of Chinese National Standards.
In this study, the effects of vacuum time, diffusion time and pressing time on the bonding strength of Larix decidua wood impregnated with Immersol-Aqua and bonded with Klebit-303 were investigated. The vacuum time, diffusion time, and pressing time were predicted by using the artificial neural network (ANN) model and multiple linear regression (MLR) methods and the results of ANN and MLR methods were compared. The highest bonding strength (7.664 N. mm-2) was achieved when the vacuum time, the diffusion time and the pressing time were 20, 60 and 60 minutes, respectively, while the lowest value (4.62 N. mm-2) was achieved when the vacuum time, the diffusion time and the pressing time were 80, 120 and 20 minutes, respectively. The model results are as follows: The MAPE value for testing phase in the ANN was 7.266 and R2 value was 0.751 whereas the MAPE value of the MLR was 9.365 and R2 value was 0.558. The ANN model has been found to have better prediction performance than the MLR model.
A process for the delignification of poplar wood using lactic acid-based deep eutectic solvents (DESs) with different hydrogen bond acceptors (choline chloride, glycine) was studied. The effect of operational parameters on the yields of the pulps and the regenerated lignins, the chemical compositions of the pulps and the delignification extent was investigated with respect to several factors, such as the types of hydrogen bond acceptor, reaction temperature and time. The maximum delignification extent of approximately 90.4% was achieved with lactic acidcholine chloride DES at 120°C for 12 h, however only about 58.4% of lignin was removed with lactic acid-glycine DES under the same reaction condition. The structural characteristics of the pulps were subsequently investigated by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Thermogravimetric Analysis (TGA) and compared with original wood sample and microcrystalline cellulose.
The work presents the influence of the way of packing the furniture on the level of emissions of volatile organic compounds (VOCs) emitted from the furniture after its unpacking. The study involved oak wood samples finished with selected varnish coating (polyurethane, waterborne and waterborne UV curable coating). After preparation the samples have been packed for 15 days into selected packaging materials: corrugated cardboard, polyurethane foam and stretch film. The VOC tests were carried out by means of the chamber test method. VOCs were analyzed by gas chromatography fitted with mass spectrometry and thermal desorption. The influence of the used type of packaging material on the level of VOCs emitted from furniture items after their immediate unpacking has been observed. The highest concentration of VOCs was found in items wrapped in stretch film while the lowest concentration was found in items packed in corrugated cardboard. That trend was irrespective of the type of coating material.
The article deals with assessing the impact of moisture content conditions in wood mass of the wood bridges constructions on their lifespan in Central Europe. Wood moisture content as one of main factors influencing the wooden elements mechanical properties was studied on seventeen wooden bridge constructions. The dependence of temperature and relative humidity on material moisture content was observed in summer season and also in winter season. The lifespan of historical and modern wood structures was discussed as well.
The paper presents experimental results of cutting power of thermally modified and non-modified hardwood of Summer oak (Quercus robur) during lengthwise milling. The process of heat treatment was performed in the atmosphere of superheated steam, at temperature 210ºC. Cutting power was determined during milling of the radial surface of modified and non-modified samples. It was calculated as the difference of power consumption by a milling machine during wood machining and at idling. Several cutting regimes were tested by combining different values of rotation speed, feed speed, rake angle and constant cutting depth ae = 1 mm. The values of cutting power are approximately the same at the kinematic angle of the tool head γ = 15°, 30°; there are bigger differences for γ = 20°. The decline of cutting power in the thermally modified (210°C) oak wood machining compared to natural oak wood is 21.7% ÷ 22.2% at the cutting speed vc =40 m. s-1.
Nowadays, there is a tendency to find new sources of biomass and to efficiently use old sources, especially to find renewable fuels. The paper aims to use grape husks resulting from the preparation of wine as pellets for combustion. Oven dry grape husk were used to be crushed and graded with the sieve of 1×1 mm in order to obtain dust for pelletizing. The pellets obtained from grape husk winery have a good density of 979 kg. m-3; a good ash content of 4.53% and a better high and low calorific value of 20.150 MJ. kg-1 and 19.850 MJ. kg-1, respectively. All over, the obtained results showed that this kind of raw material (pellets) can be use successfully when they are pelletized.
In order to guarantee a maximum quality standard of oak-barrel stored wine, (barrique), the optimization of defined phenolic and non-phenolic wood compounds (e. g. whiskey lactones), which are released into the wine during storage, is necessary to enable its unique barrique taste. Numerous factors play a crucial role for the formation of these substances within wood. Besides the origin of the wood material, also storage/drying time and defined further processing parameters are responsible for its extract composition. In the present work, oak from three different sources, which had been stored/dried for different periods, was subjected to a successively increased thermal treatment (steaming, toasting). It could be shown, that especially whiskey lactones, those wood substances, which have a decisive influence on the wine-flavor, can be controlled or increased by deliberate selection of the raw material as well as processing parameters in the course of barrel production.
WOOD RESEARCH Volume 64, Number 4
The variations of nanomechanical behavior of wood cell walls under different peak loads, loading times, and holding times were studied. Samples were separately loaded to preset peak loads of 100, 150, 200, 250 and 300 μN. Changes in the micromechanical properties were tracked in the longitudinal direction to determine change values of the elastic modulus and hardness. Moreover, the creep behavior was also analyzed under different holding times. It was found that the longer the holding time, the larger the creep ratio of all of the samples, and the creep rate decreased slowly with longer loading times. Finally, when the peak load was larger, the displacement rate and strain rate increased, but the strain rate in each test exhibited a tendency to become constant after 10 s.
This study deals with the influence of the silvicultural measures on selected mechanical properties of Scots pine (Pinus sylvestris L.) wood in the Czech Republic. Sample trees were selected at two different localities that are characteristic of Scots pine growth, and they represent two different Scots pine regeneration methods, namely the clear-cutting and shelterwood regeneration method. We tested compressive strength and impact bending strength. The density of the wood was also evaluated as a factor influencing strength characteristics. The shelterwood regeneration method shows higher values in most of the investigated characteristics (49.3 MPa for the shelterwood method and 44.6 MPa for the clear-cutting method in the case of compressive strength); however, these differences are not significant for the processing industry. Another positive effect of the shelterwood regeneration method is the even distribution of the properties within the trunk in radial direction in contrast to clear-cutting method.
The article presents research on mechanism of formation of nitric oxide during combustion of wood derivative wastes in grid furnace boilers including waste incineration plants. Considering their elemental composition (large amount of nitrogen) they require supervision in thermal processes for their treatment. Concentrations of the formed nitric oxides, depending on the parameters of the combustion process and the size of the combusted grains, were subject to evaluation. The source of nitrogen in tested wastes is urea-formaldehyde resin used as a joint. The tests proved that the dominant mechanism is fueling mechanism for formation of nitrogen oxides. It is possible to limit this mechanism with original methods that interfere directly into the combustion process in the chamber (following temperature regime, granulation and humidity of the waste, intensity of mixing waste on the grill, stream of original air in the amount adjusted to the combustion phase in the grill). The article specifies main recommendations for the conduction of thermal transformation of wastes minimizing fuel nitric oxides.
The aim of this study is to investigate properties of pulverised cellulosic material from parts of maize stalks and sugar cane bagasse (SCB). Both materials were foremost subjected to a cutting mill before boiling with water. The chemical compositions and mechanical properties of the maize stalk residues and sugar cane bagasse were performed using a TAPPI standard. Optical microscope, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Ultraviolet-visible spectroscopy (UV-Vis) were used to characterise the materials. Rind displays thinner and longer fibres, which are less unequal and almost quadrangular. In fact, it has a highest crystallinity trailed by nodes and sugar cane bagasse in sequence. Interestingly, thermal stability of SCB is dominating followed by rind and nodes.
The objective of this work was to evaluate the physical and mechanical properties of thermally compressed MDF (medium density fiberboard). For this purpose, MDF boards were subjected a combination of two temperatures (150°C and 170°C) and two pressures (25% and 50% of the perpendicular compression strength). After the treatment the following properties were assessed: bending strength and stiffness, compressive parallel strength, surface hardness, thickness swelling and water absorption after 2, 24 and 72 hours of immersion in water. It was found that in general, the results did not show any significant improvements regarding physical properties. However, mechanical properties were positively affected by treatments and densified boards had higher values than untreated boards, reaching a fourfold value in the case of the surface hardness. Regarding physical properties, there were no improvements compared to the untreated board for the thickness swelling, despite all treatments have showed lower water absorption. In general, temperature was the most important factor for physical properties and the pressure was the most important factor for mechanical properties.
To investigate the discoloration behaviour of teak (Tectona grandis Linn. fil.) during irradiation, teak veneer specimens were exposed to xenon lamp light simulating sunlight for 80 h and subsequently analysed with a colorimeter. The colour changes were explained by recording Fourier transform infrared (FTIR) and gas chromatography-mass spectrometry (GC-MS) spectra at different exposure times. Forty hours of simulated irradiation marked a key point in the colorimetric analysis. During irradiation of 40 h, the increase in the CIELAB parameters ∆a* and ∆b* originated from the generation of carbonyl derivatives that were determined by FTIR analysis. Besides that, by combining GC-MS and microscopic analyses, the decrease in ∆L* in the first 20 h resulted from extractives migrating from the interior to the surface, and that the subsequent increase in ∆L* mainly arose from volatilization of the extractives. Additionally, the decrease in ∆b* after another 40 h of irradiation was mainly due to decreasing volatile extractive contents. Our conclusion reveals the causes of photo-induced discoloration in teak.
The paper presents a design of a robotic product control system made for the wooden flange production line. The system has been designed for installation in automated production lines that allow the production of short product batches with a quick change of the type series of the manufactured products. The purpose of the work was to develop a flexible quality control system that would enable the development and adjustment of the product parameters control procedure to various product type series. The quality control station has been designed with an industrial robot and a set of 2D and 3D vision systems that take measurements of the set of parameters described for wooden flanges used in the production of cable drums. The paper presents the description of the parameters of the product subject to quality control and the premises adopted in the design process of the station. The image analysis method has been presented as developed for selected product parameters, in the scope of measurements on the image, along with the presentation of measurement results.
We aimed to develop a control method to assess compliance with International Standards for Phytosanitary Measures No.15 (ISPM 15) heat treatment wood packaging materials by physicochemical properties and chemo-metrical approach. Larix leptolepis (Siebold & Zucc.) (Gordon larch), Pseudotsuga menziesii (Douglas fir) and Picea jezoensis (spruce) as wood samples were used in this study. The ISPM 15 processing of wood did not alter the physico-chemical characteristics. By the ISPM 15 processing of wood, the core moisture content of timber was approximately 6%, regardless of the wood species, whereas that before heat treatment was 10-12%. Among the different parameters of wood, the moisture content can be classified by the PCA according to the ISPM 15 processing, which can be easily changed by mild heat treatment. Furthermore, the changes in chemical properties occurring after the ISPM 15 processing were clearly distinguished by using the ATR-PCA system.
The paper presents a method of manufacturing boards composed of lignin-cellulose chips and thermoplastic polymers (waste-based particle polymer composites, WPPC) by means of flat pressing. Rape chips, similar in size to wood chips in traditional particleboards, served as filling material, and polyethylene and polypropylene made up the outer layers. The polymers enriched only the external layers, as this allowed for considerable shortening of pressing time. The resulting boards featured satisfactory properties as compared with control, not polymer covered boards. Our study identified a temperature of 220°C and low moisture content of the polymer-containing layers as favorable for production of this type of boards. We also found out that using a sublayer with higher moisture content not only shortened the pressing time, but also improved the board properties evaluated by a bend test.
Lignin samples were separated from the black liquor of Australian eucalyptus kraft pulping by ethanol-acid precipitation or acid precipitation. Elemental analysis, FT-IR, and 1H NMR were conducted to compare their structural characteristics. The thermal behaviors were studied by TGA and heating value was examined with oxygen bomb calorimeter. The obtained C9 expanded formulas for acid-extraction lignin and ethanol-acid-extraction lignin were C9H9.52O2.96 and C9H9.58O3.18, respectively. According to FT-IR and 1H NMR analyses, the two lignins were similar to hardwood lignin of type GS. However, the acid-extraction lignin showed a high proportion of syringyl (S) unit. TG results showed that degradation process of the two lignins was similar, but their degradation temperatures were different. The weight loss rate reached its maximum value of 8.49 wt% / °C and 4.39 wt% / °C for ethanol-acid-extraction lignin and acidextraction lignin, whose temperature of maximum weight loss was 371°C and 356°C respectively. Results of oxygen bomb calorimeter tested showed the incendiary heat of ethanol-acid-extraction lignin was higher than that of acid-extraction lignin.
This paper presents results of the experimental determination of the load-bearing capacity of structural timber connections realized by nail metal connector plates as a function of nail location, length and diameter. Three different diameters of the nails have been used, specifically 2.0, 2.5, and 3.1 mm. The length of the metal nails in connectors has been determined after the detailed analysis, and kept at 20 mm during the experimental research. Nails distribution over the connector plate is such that it forms the series of equilateral triangles, so that a side of the triangle equals five times the diameter of the nails used. Preceding the testing, and while using the above listed parameters certain analysis has been done. In order to experimentally determine the load-bearing capacity of the nail metal connectors, the penetration depth, i.e. the length of the nails has been kept constant, while using three different nail diameters. The testing has been done on multiple samples in the accordance with Eurocode 5.
Development of new helical edge router bits (helix angle 15°, 30°, 45°, and 60°) with a cutting circle diameter of 8 mm was studied. The purpose of the research work was to investigate chips formation and surface roughness characteristics in milling the pine wood by the straight and helical edge bits. The generated chips were classified in four types by sieving into spiral chip (5 mesh), flow chip (10 mesh), thin chip (30 mesh), and granule chip (< 30 mesh). The experimental results showed that the spiral chip was generated most often (on a weight percentage basis) by the bits during down milling process. More flow and thin chips were produced by the bits during up milling process. Better surface roughness was produced by bits during down milling compared to up milling. When the helix angle of the bits increased the amount of spiral and flow chips were increased and granule chip was reduced. The machined surface was better in roughness (lower Ra values) as the helix angle of the bits increased both in up milling and down milling processes.
Laser shock process for circular saw blade was proposed and analyzed in this paper. The high pressure plasma shock wave generated by strong laser beam was applied to many local areas of circular saw blade to generate local plastic deformation. Resistance strain rosette and static strain acquisition instrument were used for measuring the stress field of laser shocked circular saw blade. The natural frequency of circular saw blade after laser shock process was tested by hammer vibration test method. Based on reasonable simplification and hypothesis, laser shock process for circular saw blade was built by finite element method. The stress field obtained by experiment and theoretical calculation shows that investigated process is feasible. The natural frequencies of laser shocked circular saw blade for nodal diameters Nd = 2 and Nd = 3 are increased which means that the dynamic stability of circular saw blade is enhanced after modification.
This paper describes the characterization of four wood species (alder, oak, jatoba and obeche) with regards to their machinability, i.e. susceptibility to mechanical processing expressed by different machinability indicators. Three types of tests were performed. Drilling tests were conducted on a computer numerical control (CNC) working center as well as on a conventional vertical drilling machine. Both machines were fully instrumented with transducers to continuously measure the torque and the thrust force while drilling. Scratching tests were performed on an instrumented shaper, allowing continuous measurement of the normal and tangential components of the total force applied on a cutter while cutting. This resulted in correlations between particular machinability indicators that were estimated with usage of different measurement benches. Moreover, machinability indicators obtained in this way were compared to the mechanical properties of the wood species. Especially strong correlations were obtained with density or strength in static bending. Those alternative techniques were to some extent coincidental. Particularly, similar results occurred with assessments on CNC machine indicators (torque and thrust force) and friction coefficients (MIε-drilling) during drilling on a conventional drilling machine or indicator C2. The necessity of some improvements in fitting the geometry of an elementary cutter regards to specific properties…
Friction is an important factor during cutting of wood. Micro-texture has been proven to be an effective measure for the improvement of material friction performance. This paper investigates the effect of the cemented carbide surface micro-pits texture on the performance of wood cutting tools with the purpose to reduce the coefficient of friction on knife/workpiece contact zone. Birch (Betula spp.) and pine (Pinus sylvestris) were selected as the research object, the impacts of wood moisture content and the load used on the friction coefficient of different micropits structures were assessed and compared. We found that at a diameter of the micro-texture of 60 μm, the coefficient of friction can be effectively reduced at different wood moisture contents. The average friction coefficient between cemented carbide and wood surface increased with increasing moisture content below fiber saturation point (FSP). But the increase in free water quantity can lead to a more considerable decrease in the friction coefficient. At a higher working load, the value of the average coefficient of friction between the surfaces increases.
The sound insulation performance and mechanical properties of medium density fiberboard (MDF) and rubber multilayer panels were studied. The MDF and rubber materials were compounded under certain conditions of hot pressing, temperature and amount of glue. The weighted sound reduction was 28.0 dB for 6 mm MDF, while it was 37.4 dB for 6 mm wood composite damping material, increased by 25.1%. Compared to the monolayer MDF, the composite panels showed increased sound insulation at the resonant frequency, and the critical frequency moved to a higher frequency. The coincidence valley became shallow, effectively suppressing the anastomosis effect. As the rubber thickness increased, the multilayer composite material exhibited enhanced sound insulation efficiency and mechanical properties, and the damping properties of the composite increased, making the composite resistant to bending deformations caused by incident sound waves.
Pressure-sensitive adhesives consisting of polymer (t-butyl acrylate, PtBA) was widely used to repair aging paper. Over time, whiteness, mechanical properties and durability of paper degrade with the aging of adhesive. In this study, novel paper-friendly glue-remover (GR), consisting of organic solvents, was designed for removal of PtBA from aging paper. Dichloromethane and hexane were screened to prepare GR according the swelling degree of aged adhesive. For detail, the component of GR was adjusted to optimize removal effect and minimize the damage of GR on aged paper. Treated with GR consisting of 40% (v/v) dichloromethane/ normal hexane, the removal rate of PtBA was high to 56%. Results of mechanical and chromatism test indicates the GR will not damage the mechanical strength or handwriting on the paper. Moreover, the pH of paper increased from 3.55 to 5.75 after removal of glue, which suggested that GR help remove acid from aging paper.
WOOD RESEARCH Volume 64, Number 5
Aquilaria sp. is one of the tree species that produce agarwood. Agarwood is a kind of wood that has high content of fragrant resin and high economic values. Sufficient information about wood anatomical characteristic of agarwood-producing species is essential in agarwood trading, especially for identification and verification of wood. Therefore, this research aims to observe wood anatomical features of Aquilaria sp. and to observe its cell morphology. Five trees and five seedlings of Aquilaria sp. were used for the experiment. The results showed that the wood of Aquilaria sp. can be determined according to IAWA List of Hardwood for Identification with anatomical features nos. 2, 5, 10, 13, 22, 24, 29, 30, 40, 48, 49, 52, 58, 62, 66, 68, 71, 79, 92, 97, 105/104, 112, 115 and 134. Furthermore, seedling and trees of Aquilaria sp. have similar anatomical features but they have some differences on the cells morphology.
The present article aimed to characterize the wood specie Qualea albiflora (Mandioqueira), in order to enable its use for structural purposes. The tests to obtain the physical and mechanical characteristics were carried out according to the Brazilian standard ABNT NBR 7190, allowing the classification of the Qualea albiflora in the strength class C60, a wood species suitable for use in heavy constructions. After the characterization, it was verified with the aid of regression models (linear, logarithmic, exponential and geometric), that it is not possible to make use of the apparent density in the estimation of the other physical and mechanical characteristics, obtaining a bad adjustment in all the cases (R² < 50.00%) and the non-representativeness of the models adopted (P-Value> 0.05).
Our previous study revealed that treatment with aqueous styrene/acrylic acid copolymer (SA) is a cell-lumen filling process, and the treated wood exhibited negative values for cell wall bulking efficiency (BE) and anti-swelling efficiency (ASE). In this study, three low-molecular-weight agents (LMWAs), 1, 3-dimethylol-4, 5-dihydroxyethyleneurea (DM, 10%), glutaraldehyde (GA, 10%), and n-methylol acrylamide (NMA, 10%), were separately combined with SA (5, 10, 15, or 20%) and used to modify radiata pine wood at the levels of cell walls and cell lumens. The combinative treatments caused positive BE and ASE values, indicating restrained wood deformation, likely due to the diffusion and reaction of LMWAs in the wood cell walls. Infrared spectroscopy and dynamic mechanical analysis showed that LMWAs exhibit little reaction with SA, and the SA copolymer retains thermoplasticity in the wood cell lumen. The combinative treatments resulted in considerable improvement in bending modulus, bending strength, and compression strength of wood of 36, 36, and 124%, respectively, but there was little effect on impact strength. These findings confirm that LMWAs can act as cell wall modifying agents to synergistically improve wood properties, especially the dimensionally stability, when used together with SA.
This study deals with the variability of wood density, compression strength and the impact bending strength within the trunk of Scots pine (Pinus sylvestris L.). The impact of the site on the examined properties was also evaluated. The tree samplers come from four different sites that are representative for Scots pine growth in the Czech Republic. From the samplers the sections representing a basal part of the trunk and a middle part of the tree were cut. The most significant influence of the site was confirmed for wood density; on the other hand, the influence of the site is ambiguous in terms of the examined strength characteristics. A decrease in the wood properties with increasing trunk height was proven for all tested properties. The highest impact of the position was observed for wood density, while the results of vertical variability in mechanical properties are not always significant (compression strength: basal 47.1 MPa and middle 45.8 MPa). A close correlation between mechanical properties and wood density was also proven.
This study explored acetylation of wood of Larix kaempferi (Lamb.) Carr. and Pinus sylvestris var. mongolica Litv. without catalysts or solvents. Both wood samples were impregnated with acetic anhydride and subsequently heated to 120°C for different reaction durations (0.5-8 h) in the esterification reagent. The extent of acetylation was measured by weight percent gain (WPG), which varied from 12.0% to 21.7% and 13.6% to 22.3% for both wood species. The cell wall bulking and anti-shrink efficiency (ASE) started to increase faster and then increase slower with increasing reaction time. As the WPG reached 19.2% and 17.8% or more separately, ASE of both acetylated wood were above 50% in any RH conditions. FTIR, CP/MAS 13C NMR, and XPS studies produced evidences for acetylation of both wood species. The degree of acetylation of wood cell wall polymers increased with increasing WPG, but during the process degradation of lignin and acid hydrolysis of carbohydrates occurred.
Larch (Larix decidua L.) wood samples were steamed applying broad range of steaming time (0-20 days) at 90°C and 110°C steaming temperatures. The colour change was monitored by objective colour measurement using the CIE Lab colour system. The initial colour of earlywood and latewood within sapwood and heartwood has highly different values for larch wood. Wide range of colours was created by steaming between the initial colour and brown colour depending on the steaming time and temperature. The steaming produced excellent colour homogenisation and resulted in an increase of saturation. The redness showed the greatest homogenisation effect. The redness value difference among the tissues was seven times smaller after 9 days of steaming at 110°C than the initial redness difference. The yellowness values increased and moved toward each other during steaming. The results showed that the best visualisation effect of homogenisation can be presented on the a*-b* plane. The colour saturation of the examined tissues increased considerably and showed homogenisation effect as well. Because of the colour homogenization, it was difficult to differentiate sapwood and heartwood at the end of the steaming process at 110°C. The effective steaming time for colour homogenisation was 5 and 2 days at 90°C and…
The aim of this research was to prepare lignocellulose films reinforced with chitosan (CS), nano-ZnO (NZO), or nano-TiO2 (NTD) by casting method. The chemical structures of the films were characterized with FT-IR, which showed no chemical bonds formed but certain interactions among the hydrogen bonds. X-ray diffraction confirmed that the main structure of blend films was unchanged comparing to lignocellulose film. Derivative thermogravimetry (DTG) presented that the residual masses of lignocellulose/chitosan (LCCS) film, lignocellulose/TiO2 (LCTD) film, and lignocellulose/ZnO (LCZO) film were 23.43%, 19.27%, 27.68% at 700°C, respectively. Ultimate tensile strength and strain to break of all blend films were decreased with addition of CS, NZO, and NTD, respectively. LCCS film was more effective against Escherichia coli and Staphylococcus aureus than LCTD film and LCZO film. Potential antimicrobial applications in the orthopedic field and perspectives regarding future studies in this field were also considered.
The study on wood physical properties of Quercus robur L., Quercus petraea (Matts) Liebl., and Quercus pyrenaica Willd., to use in wine aging was also founded on the relationship between porosity and void ratio to assess its variation in the oak species under study. A total of 45 oak trees were chosen in 15 oak stands of the Lugo and Ourense provinces (Galicia, northwestern Iberian Peninsula). Altogether, were obtained forty-five fine slices of wood at 60 cm tall on the trunk, and 194 wood test specimens’ parallelepipeds of 20 × 20 × 40 mm ± 1mm. On average, oak species in Galicia have lower porosity than oaks of the French regions of Limousin and Vosges. With a width of growth ring and age similar, Quercus pyrenaica has porosity slightly lower than Q. robur and Q. petraea. Our objective is to carry out a complete description on the wood physical properties of the studied species for its possible use in the cooperage industry and wine aging. For that, the aim of this work was to estimate the porosity versus the void ratio.
A furfuryl alcohol-formaldehyde resin was synthesized as a crosslinker in our laboratory to develop a mimosa tannin-based adhesive with good water resistance. 13C nuclear magnetic resonance and matrix-assisted laser desorption ionization time-of-flight mass spectroscopy indicated that furfuryl alcohol reacted with formaldehyde under acidic conditions and that–CH (–OH) - groups to be the ones involved in the crosslinking of mimosa tannin-furfuryl alcoholformaldehyde adhesive (TFF). The wet shear strength of TFF-bonded plywood suggested that the cured TFF adhesive was better than mimosa tannin-furfuryl alcohol (TF) adhesive. The water resistance of TFF adhesive cross-linked with 9% epoxy resin was also higher than those of TFF and TF adhesives.
This article focuses on thermal engineering assessment of light building envelope structures using Finite Element Method (FEM). The research was carried out for a particular composition of a lightweight perimeter wall in winter, for which continuous experimental measurements are also carried out. In the preparation of calculation models for numerical simulation, the marginal conditions, which were obtained by experimental measurement, were used. Thus, for simulation purposes, the construction was loaded under the same boundary conditions as the actual structure being monitored within which experimental measurements were performed. The results of the experimental measurement made it possible to compare the actual measured data with the results of the numerical simulation. The difference between calculated and experimentally determined temperatures was in the range from 0.1°C to 1.3°C. This study demonstrated, that with the help of suitable simulation programs, it is possible to predict the thermal-technical behavior of lightweight perimeter constructions.
Steam exploded lignin (SEL) thermal decomposition was investigated by thermogravimetric technique (TG/DTG) within the temperature range from room temperature to 920°C under different heating rates (10, 20, 30, 40, and 50°C. min-1). Little differences in the mass losses with heating rates were observed from TG analysis. It was established that SEL pyrolysis consisted of three main stages: water evaporation (< 200°C); devolatilization of organic volatiles (200-600°C); and char formation (> 600°C). The kinetic processing of non-isothermal TG/DTG data was performed by model-free methods proposed by Flynn-Wall-Ozawa (FWO) and Kissing-Akahira-Sunose (KAS). The average activation energies calculated from FWO and KAS methods are 74.2 kJ. mol-1 and 173.2 kJ. mol-1, respectively. Experimental results showed that values of kinetic parameters from both methods were analogous and could be successfully applied to understand the complex degradation mechanism of SEL. It is also helpful to achieve a better understanding of the devolatilization process of different type of biomass.
The paper is focused on the analysis of cutting forces in milling of MDF on the CNC machine (SCM Tech 99 L, SCM Group, Italy). The measurement of the forces was realized by a three-axis piezoelectric dynamometer Kistler 9257B (Kistler Holding AG, Switzerland). The forces were examined and analysed during quasi-orthogonal milling with a single-edged blade. The resulting forces were compared to each other depending on the conventional and climb milling of the edge of the MDF at changing feed speeds from 1.5 to 4.5 m∙min-1 with steps of 0.75 m∙min-1. The experimental values of cutting forces were also used for the first assessment of the fracture toughness and shear yield strength, main parameters of computational model based on Ernst-Merchant theory and on fracture mechanics. These values were input data for the calculation of the specific cutting resistance for CNC machining. The experimental data confirmed that the cutting force increases and the specific cutting resistance decreases with the increasing chip thickness.
The purpose of this study was to investigate the enhancement effect of composite column on axial compression. Four full-scale composite columns and one Chinese fir (Cunninghamia lanceolata) column were fabricated and tested under axial compression load to study the enhancement effect of composite column. The compressive, bending properties of bamboo (Phyllostachys edulis) rod and Chinese fir were tested respectively. The ultimate axial load capacity, midpoint lateral displacement, failure mode of composite column and Chinese fir column were also investigated. The test results indicated that the harmonious coordination between bamboo rods and Chinese fir was shown under the axial load process, and the axial compressive strength 26.21 MPa and compressive modulus of elasticity 9.46 GPa of the composite column were increased significantly meanwhile the lateral displacement at the midpoint of composite columns was reduced by 9.61 mm compared with that of Chinese fir column, and the failure patterns of two types of columns were different. The results will provide a theoretical basis for the popularization and application of bamboo and Chinese fir composite columns.
Reaction beech wood has different anatomical and also chemical characteristics than normal (opposite) wood. The difference in density is conditioned by percentage of G–layer. Fibers cells in reaction beech wood have a different cell wall structure and a different chemical composition, as well. Longitudinal contraction was noticeable in reaction (tension) samples, where it was several times higher, what could be expected considering the physical properties of reaction beech wood. Our measurements confirmed that drying time has remarkable effect on longitudinal contraction. Higher longitudinal contraction was measured in temperature 60°C and 120°C, which had almost identical drying time. The issue of variability initial moistures did not affect the drying process and samples reached approximately equal final moisture content. Reaction beech wood is a very serious problem in nowadays wood production.
In this study, it is aimed to determine both the tensile-shear strengths of plywood that produced by using phenol formaldehyde resin from Uludağ fir (Abies nordmanniana subsp. bornmülleriana Mattf.), alder (Alnus glutinosa L.), scots pine (Pinus sylvestris L.) and Samsun poplar (77/51 Populus deltoides Bartr.) trees rotary cut veneers combinations of poplar-pine, poplarfir, poplar-alder and poplar wood along with the effect of wood types on adhesion quality of glue. According to standards TS 3969 EN 314-1, and TS EN 314-2 adhesion class 3, the test specimens were prepared and tested for the adhesion quality. The obtained data were analyzed statistically by using SPSS 22 statistical program. As a result, the tensile-shear strength values of poplar, pinepoplar, fir- poplar and alder-poplar plywood types were found to be as averages 1.34 N. mm-2, 1.66 N. mm-2, 2.18 N. mm-2 and 2.46 N. mm-2 respectively. Also, it was found that there was no significant difference between the alder poplar and fir-poplar plywood types about tensile-shear strength. Since these all plywood combinations are satisfied the required 1 N. mm-2 strength value according to TS EN 314-2, all plywood types in this study are of suitable quality for outdoor uses.
This study examined the mechanics and temperature during a wood dowel welding process. The test results indicated that the welded depth 40 mm showed the highest pullout resistance. Based on the mechanics and surface morphology, welded depth 30 mm was the optimal parameter. A nonlinear relation existed between pullout resistance and welded depth. The highest temperature of six test points was studied in group of welded depth 30 mm. With the increasing of depth, the highest temperature of six test points showed the decreased trend. A linear relation was found between the highest temperature of welding interface and the depth.
WOOD RESEARCH Volume 64, Number 6
The research performed exhaustive experiments to help better understand how subterranean termite colonies function in their biodegradation activity in wooden structural elements. Specifically, the research had as main objectives to analyse the usefulness of CO2 as a bioindicator of the presence of termites and their wood biodegradation activity. The obtained results have demonstrated that CO2 emissions of termite colonies vary depending on their wood degradation activity. So, the amount of CO2 emitted is closely linked to the population size and activity levels. The obtained relationship between the CO2 concentration and time for different population sizes can predict termite biodegradation severity and help establish predictive models for pest monitoring in wood structures.
Compression wood is an ideal model for exploring the molecular mechanism of wood formation. To supplement the proteome data in compression wood formation, two-dimensional difference gel electrophoresis (2D-DIGE) proteome technology was used to investigate the protein response to bending the stem of Pinus koraiensis seedlings. The results showed that most of the proteins in wood-formation tissues were distributed in pH from 4-8 and the molecular weight was around 30-97 KDa. In total 24 identified proteins were mainly functional on amino acid metabolism, cell wall synthesis, secondary metabolism, and stress response. Proteins related to methionine pathway and lignin biosynthesis were up-regulated in the formation of the compression wood. On the contrary, lipid metabolism-related proteins were down-regulated during the formation of the compression wood. In additional, some proteins involved in energy metabolism and photosystem were also changed in the tissues during the formation of the compression wood. These findings suggested that 2D-DIGE was a feasible and timesaving technology in proteome analysis of wood-forming tissue. Moreover, proteins were not involved in lignin synthesis pathways, but other metabolites were changed as a response to stem bent treatment. The identified proteins in compression wood formation insight to further investigating the molecular mechanism of wood cell…
In this study, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Fouriertransform infrared spectroscopy (FT-IR) methods were used to study the structure and the thermal degradation of the cellulose modified with silver nitrate, silver sulphate and silver borate. The absorption of the nitrate derivative is more intense followed by the borate. All the cellulose derivatives showed two degradation steps, except for bromate derivatives which indicated the third peak that is related to a nature and chemistry of a derivative presence. The modification seems competent for an application for modified fillers in polymer composites.
Samples were vacuum-pressure treated with nano-SiO2 water solutions with BET specific surface area of 60,150, 200, 380 respectively, and then impregnated with copper azole (CuAz) preservatives or emulsified wax modified CuAz preservatives. The effects of emulsified wax and nano-SiO2 on the dimensional stability were investigated according to standard GB/T 1934 (2009) after one year outdoor exposure test. The results showed that the addition of nano-SiO2 or/and emulsified wax could reduce the water absorption rate of treated wood, and the best water repellent was observed in the samples treated with BET specific surface area of 60 m2.g-1. The addition of wax into nano-SiO2 modified wood was essential to improve the radial and tangential swelling and shrinkage stability of nano-SiO2 treated wood. The bigger BET specific surface area of nano-SiO2 would be adversely affected the dimensional stability of the treated wood.
In this study, the changes of the individual constituents of wood, mainly lignin fraction, and carbohydrate fraction of partially delignified wood chips were investigated. The concentration of alkali during kraft cooking of spruce chips were characterized with respect to the time of kraft cooking, consumed alkali and also to the time-temperature variable (H-factor). The observation brought a new fact, that the extraction of lignin and degradation of the carbohydrate fraction as well as the wood residue itself, were realized in two different reaction phases: initial and residual. The power form dependences between the studied constituents of the wood during kraft cooking were interpreted in a logarithmic coordinate system by the straight line relationship.
This study was designed to investigate some surface characteristics such as gloss, color, and surface hardness changes of Scots pine wood preimpregnated with some copper-based chemicals before varnish coating after accelerated weathering. While Adolit KD-5 (AD-KD 5), Wolmanit CX-8 (WCX-8), and Celcure AC-500 (CAC-500) were used as copper-based impregnation chemicals, water-based varnish (WBV) was used as a coating material. Results showed that surface hardness and gloss values of Scots pine were increased after accelerated weathering. Impregnated and WBV coated Scots pine gave better surface characteristics compared to only WBV coated Scots pine. In impregnation chemicals, while AD-KD 5 showed the most appropriate chemical, in terms of surface hardness and total color changes, CAC-500 was found the most valuable chemical in terms of gloss changes after 1000 h accelerated weathering exposure.
The objective of this study was to investigate odor active compounds of polyvinyl chloride (PVC) laminated medium density fiberboard (MDF) and explore the effect of temperature on total volatile organic compound (TVOC) and odor emissions. A micro thermal extractor was used based on the technology of gas chromatography–mass spectroscopy/olfactometry. The results showed that fruity, sweet, fragrant, and aromatic were the dominant odor impressions of PVC laminated MDF and were primarily concentrated in aromatics. Decoration treatment could effectively prevent the release of some odor compounds from MDF, yet these could add new odor substances. In the test period, the total odor intensity of MDF decreased more rapidly than that of PVC because of the characteristic of exposure. The TVOC from PVC increased when the temperature increased, and the effect was more significant early in the test period. Increasing temperature could accelerate the appearance of some odor active substances. The fastest release of odorant compounds occurred at 40°C. At higher temperature (60°C in this experiment), some substances could be enhanced, causing an increase in TVOC and odor. The temperature contrast between 40°C and 60°C contributed greatly to the release of alkanes, alcohols, esters, and ketones.
The objective of this study was to investigate the basic wood density (ρk) of the silver birch (Betula pendula Roth.) trees in relation to the stand structure. This research was conducted in three stands of different structure and ages, located in the region of the lower part of the Jeseníky Mountains in the Czech Republic. In total, 71 healthy dominant silver birch trees were randomly selected. Two samples (cores) were taken per tree for performing the tree-ring width analysis and ρk determination. We found that the average ρk of the three examined stands ranged from 471.8 to 494.6 kg. m-3. The older trees showed a high variation of the ρk. The age of the tree and stem diameter positively influenced the ρk. Nevertheless, it was noted that the slenderness ratio had a negative influence on the ρk. Overall, the prediction of wood density using stand and tree characteristics, even when the management history records are available, remains a complex hypothesis.
This article describes techniques used to study mixed biomass fiberboards based on the simulation of wood composition, in which high-strength bamboo could serve as wood cellulose, low-density poplar could serve as wood hemicelluloses, and lignin-rich walnut shells could serve as wood lignin. The effects of different material mass ratios on board properties were discussed, and the bonding mechanisms of the mixed binderless composites were analyzed through Fourier transform infrared spectroscopy (FTIR) and environmental scanning electron microscopy (ESEM). Experimental results showed that the simulation could identify bio-fiberboard compositions with good performance.
One-layer bark panels were internally reinforced with two different grid sizes fiberglass mesh sheets (M1 and M2). The thermal conductivity, water absorption, thickness swelling, static bending properties and internal bond strength of these panels were tested. The reinforcement doesn’t affect the thermal conductivity, but the physical and mechanical properties of the panel were improved. The thickness swelling was reduced by 7.43% and 12.93%; the water uptake decreased by 4.93% and 16.32% for the M1 and M2 sheets, respectively. MOR increased from 0.54 MPa to 2.44 and 2.1 MPa, and MOE increased from 0.28 GPa to 0.66 and 0.63 GPa, respectively. The internal bond didn’t change. The findings indicate that it is possible to produce internal reinforced bark panels for insulation materials depending on the characteristics and tensile properties of the reinforcing materials, as well as the adhesion properties and interfacial interaction of the composite materials.
Heat-treatment woods of Betula alnoides were prepared by using vapor as the heat-conducting medium. Effects of heat-treatment time and heat-treatment temperature on equilibrium moisture content, density, pH value, contact angle and bonding performance of Betula alnoides were discussed in this paper. The results indicated that: (1) With the increase of heat-treatment temperature, the equilibrium moisture content, density and pH value of Betula alnoides decreased gradually. (2) With the increase of heat-treatment temperature, the contact angle of Betula alnoides increased from 70.08° to about 100°, resulting in the reduction of bonding strength gradually. Bonding strength of Betula alnoides after heat-treatment was related with the used adhesive. Bonding strength of different adhesives decreased to different extents. The bonding strength of Betula alnoides wood with polyvinyl acetate (PVAC) resin was generally higher than that of melamine-urea-formaldehyde (MUF) resin. The former were 6.35-4.56 MPa, and the latter were 5.60-3.00 MPa. (3) Heat-treatment time influenced equilibrium moisture content, density, contact angle, pH value and bonding strength of Betula alnoides less than heat-treatment temperature. (4) Heat-treatment could affect strength and surface performance of Betula alnoides greatly and the processing medium should be extended.
This study conducted to quantify and compare the variation among root, stem, and branch wood of Acacia salicina and Albizia lebbeck. Results of this study revealed that the proportion of wood elements is quite similar. The wood cells decrease in length and width (diameter) in the acropetal direction. These traits indicate the principles of the hydraulic architecture of a tree as a perfect adaptation for maintaining the pressure gradient. A. lebbeck has the higher hydraulic conductivity and non-lumen fraction value. It indicates that A. lebbeck has a higher photosynthetic capacity and specific gravity. Thereafter, all of the vulnerability indexes are greater than 3, so both of examined species categorise as mesomorphy species. However, in arid circumstance, A. salicina is potentially much stronger to withstand drought-prone than A. lebbeck.
In this paper, the warpage of the Taxodium hybrid 'zhongshanshan' veneer was measured by 3D laser scanning technology. The results showed that, the deformation of this veneer was mainly due to the warpage phenomenon along the cross striation of the wood. Air-drying shrinkage clearly enlarged the length in the direction of cross striation compared to the direction of parallel grain. The air-dried veneer would incline 7-12° along the direction of the parallel axis. When peeling the wood of the Taxodium hybrid 'zhong shan shan', the diameter decreased, and the warpage degree of veneer increased. The average veneer warpage degree of sapwood was 21.18%, the intermediate wood was 28.20%, and the heartwood near piths was 40.88%. High resolution 3D laser scanning technology accurately, intuitively, and rapidly obtained the deformation of the veneer.
In this paper, an experimental research on bending behaviour of end-notched glulam beams and their bending behaviour after repairing with glass fibre reinforced polymer (GFRP) bars is presented. Altogether five glulam beams (100 x 220 x 4000 mm) made of spruce timber classified in the strength class C22 were tested. Experiment showed that originally, the beams failed in a brittle manner due to crack opening and its propagation. Cracks in the notch details were a result of excessive tensile stresses perpendicular to grain and shear stresses. Repairing the beams with GFRP bars after their failure completely restored and notably improved their load carrying capacity (average increase of 194%). Failure mechanism after repair changed from the original brittle tensile failure to more ductile failure in bending for most beams, proving the successfulness of the intervention. This study gives an insight in rehabilitation and repair possibilities of existing structures using advanced materials like GFRP bars.
This study was carried out to compare to the effects of glass-fiber fabric, which might be a new alternative edge band, to PVC and wood veneer edge bands which is used commonly in today’s furniture in wood-based materials melamine impregnated paper coated medium-density fiberboard and melamine impregnated paper coated particleboard on strength of corner joints. For this purpose, the 0.4 mm wood veneer, 0.4 mm PVC, 4 mm PVC, and fabric edge band were used as the edge bands. It was prepared 13 different configurations. The prepared test samples were subjected to the tension and compression tests. The data from the experiments was evaluated by means of multiple variance analysis. This study showed that the joint with the fabric edge band was 34% and 30% higher than 2 mm PVC band, 26% and 23% 0.4 mm PVC band, 22% and 22% 0.4 mm wood veneer band, and 16% and 23% higher than control (for tension and compression, respectively). In addition to, it is to be understood that the fabric may be used like as commercially available edge bands.
To characterize the delamination process of Ceiba plywood, an energy approach was used. This approach considers that crack propagation is a phenomenon of energy dissipation. The fundamental parameter of this approach is the energy release rate (G). To determine this parameter in pure mode I (GI), a Double Cantilever Beam test (DCB) was deployed. The critical energy release rate in pure mode I (GIC) is determined using four approaches, namely Beam Theory, Berry compliance law, Modified Beam Theory and the Compliance Calibration method. Then, a resistance curve of Ceiba plywood was determined according to each approach. Finally, a fracture surfaces analysis was discussed to understand the nature and types of fracture.
Volume 63 (2018)
WOOD RESEARCH Volume 63, Number 1
In this study, a wooden Nabataean coffin box from Jordan was examined and investigated for its conservation. The previously neglected coffin box was subject to various problems such as fragility, structural disintegration, and biological degradation. Microscopic examination using transmitted light microscope and scanning electron microscope showed the coffin box to be constructed of Lebanon cedar wood. Microbiological investigations allowed the isolation and identification of the fungal and bacterial species that have contributed to the biological degradation of the object. Non-destructive ultrasonic velocity measurements were carried out on the coffin wood to evaluate its deterioration level and to assess the effectiveness of consolidation treatments. Based on these analyses, several conservation processes were carried out on the object. These include cleaning, sterilization, consolidation, and reconstruction. For the consolidation of the coffin box, four different consolidation products were tested. Using ultrasonic technique, Paraloid B72 proved to be the most effective consolidation material for application on the coffin.
The article presents tests concerning efficiency of combustion process in a layer by defining quantitative evaluation indicators (localization of reaction (flame) front, ignition rate, mass loss rate, thermal load of the grate). Wood wastes of various grain size were subject of tests. Obtained results for pure wood and paper have also been presented for comparison. Experimental tests were carried out on laboratory scale. The advantage of such tests is large saving of costs which would have to be incurred for tests performed on a real object. Received values of the quantitative indexes may be used by shifting them from the devices in laboratory scale into industrial devices. They help in selecting technical parameters for the systems. Furthermore, they help to avoid errors of input data at the stage of realization of the new or modernized project of the incineration plant. The results show that the tested wood waste were similar regarding their physicochemical properties. The differences can be observed in heating values (14.30-19.91 MJ∙kg-1). The rate of ignition for all investigated materials is high (0.021-0.063 kg∙(m-2s-1)). Values of SZ and SUM are similar which suggests that the probability of unburned fraction of waste remaining at the end of grate of…
Using NMMO-cellulose membrane as a matrix, Fe3O4/ cellulose composite membrane were prepared by the in-situ co-precipitation method. The effects of Fe2+ and Fe3+ salts concentration on the structure and properties of composite membranes were studied by scanning electron microscopy(SEM), X-ray diffraction(XRD), Fourier transform infrared spectrometer(FTIR) and vibrating sample magnetometer(VSM). Results showed that the spherical magnetic Fe3O4 nanoparticleswere dispersed uniformly and immobilized in the cellulose membranes, and there were good interactions between cellulose and Fe3O4 in the membranes. With increased iron ion content, the thermal stability of Fe3O4-CMgradually increases, and the complex membrane has a second significant weightlessness peak within 620–700 °C. In addition, it is also found that Fe3O4/cellulose composite membranes showed good superparamagnetic property.
The article describes the method of evaluation and preparation of fluting liners produced from semichemical pulp obtained from waste wood particle boards (PB) and oriented strand boards (OSB). The semichemical pulp was obtained using an alkaline cooking process from a sorted fraction of the 4-8 mm chips. Properties as thickness, bulk density, air resistance of paper sheet, tensile strength, tensile index, breaking length, burst index, CMT30 and SCT were monitored on lab sheets 127 g. m-2 and 170 g. m-2. Values of pH and residual NaOH were determined in the batch leachate.
The preparation, structures and properties of UF resin prepared with concentrated formaldehyde at a low molar ratio F/U=1.1 were studied in this paper. According to the results obtained from 13C-NMR, FT-IR and DMA, UF resin prepared with concentrated formaldehyde showed better mechanical properties and heat resistance and lower formaldehyde emission responsible for its high degree of polycondensation and crosslinking than that of UF prepared with common formaldehyde, but its stability was so bad due to its high content of ether bridges. However, it was stated that adding hydrolyzed soy protein to this UF resin at the first alkali preparation stage of “alkali-acid-alkali”, its stability got improved due to the increase of methylene bridges, which was the key contribution to polycondensation.
The aim of this study was to explore the structure of the basic biometric characteristics of Canadian poplar (Populus x canadensis Moench) growing on former farmland, and the influence of meteorological elements on the variability of tree-ring widths (TRW). The test was performed on stem discs. Measurements of TRW were made with the use of LINTABTM 6. The impact of meteorological conditions on the TRW of the examined poplars was determined using correlation analysis for the dependent variable - residual chronology and independent variables - rainfall and air temperature in the current year and the year preceding the formation of rings. The average TRW of the Canadian poplar was 6.70 mm, with a coefficient of variation of 45.6%. The average TRW in sapwood was 5.37 mm, 2.11 mm less than in heartwood. The site chronology represented the period 1967-2014 (48 years). Our study demonstrated a significant correlation between rainfall and temperature on TRW in Populus x canadensis. The greatest demand for water by the Canadian poplar was observed in April and September of the current year. In contrast, the effect of air temperature most negatively affected TRW in June-July of the previous year (especially July) and April-May of the current…
The purpose of this study was to evaluate adhesion strength of phenol formaldehyde (PF) and melamine urea formaldehyde (MUF) adhesives modified with nano-technological products on the adhesion strength of different wood species. For this purpose, the effect of nano-TiO2 and nano-SiO2 on bonding performance and structural properties of PF and MUF were researced. And also, TiO2 and SiO2 chemicals were chosen as a rate of 2%, 4%, 6%, 8% within the adhesives. The bonding strength tests of the acquired Uludag fir and aspen boards were measured with a Universal Zwick Roell brand testing device in accordance with TS EN 205 standards. The obtained results showed that the highest bonding strength for Uludag fir wood was 8.27 N. mm-2 with PF adhesive mixed as 8% of SiO2 and the lowest was 5.91 N. mm-2 with MUF adhesive mixed as 2% TiO2, respectively. For aspen wood, the highest value was determined as 7.32 N. mm-2 with PF adhesive into which 8% of TiO2 had been added and the lowest was as 5.55 N. mm-2 with MUF adhesive into which % 6 TiO2 had been added. In conclusion it was determined that compared to the control samples the bonding strength of wood materials…
This paper deals with the results of experimental determination of load-bearing capacity of structural timber connections realized by nail metal connector plates, in the function of nail to steel plate connection rigidity. In the first group of test samples, the nails are embedded in pre-drilled holes in the steel plate. In the second group, the nails are embedded in pre-drilled holes and then the head of nail is welded to steel plate by its circumference. The main originality of the study is reflected in the achievement of rigidity of the connection of nails and the sleet plate, that is, in provision of rotation resistance, which leads to the plastic hinge formation at the surface of the steel plate, and thus to the increase of connection ductility. The study showed to what extent the degree of nail-to-plate connection rigidity affects the load-bearing capacity of structural timber member connections. Experimental testing was conducted in accordance with the provisions of Eurocode 5.
This research investigated the potential use of condensate generated during vacuum drying with high frequency of wood in the synthesis of urea-formaldehde (UF) and melamineformaldehyde (MUF) resins. The liquid condensate (5 wt%) of total resin composition) of walnut, beech or oak was replaced with deionized water used in the synthesis of UF and MUF resins. The condensate did not affect the properties of the UF and MUF resins in terms of density, solid content, viscosity, pH, and gel time as compared with the control resins. The control UF and MUF resins did not show a significant difference with the bond strength of UF and MUF resins at dry and wet conditions, except for the oak-UF resin. As for the dry condition, the control resin had the highest bond strength with a value of 12.9 N. mm-2, followed by beech-UF resin (12.6 N. mm-2), walnut-UF resin (12.1 N. mm-2), and oak-UF resin (11.8 N. mm-2), respectively. A similar trend was observed for the wet condition. All the modified UF and MUF resins complied with the minimum requirements of EN 12765 standard at dry and wet conditions. The results of this research can be useful for environmentally friend solution of the waste…
A bending strength test was carried out on the strip-type cross-laminated timber (3 layers) that was combined differently by the cross-sectional annual ring orientation of the laminae under the same modulus of elasticity combination. In addition, the bending modulus of elasticity and the maximum bending moment predicted using the gamma method were compared with the results of the actual test. The result of the bending strength test showed no significant difference in bending strength among the specimens combined according to the annual ring orientation. Furthermore, when the outer tension layer of the cross-laminated timber was strengthened with a glass-fiber-reinforced plastic plate (volume ratio: 1.2%), the modulus of elasticity and the modulus of rupture increased by 4.2% and 16.3%, respectively. The ratios of the prediction results for the bending modulus of elasticity and the maximum bending moment by the gamma method to the actual test values were 1.01 and 0.96 on average, respectively, indicating that the two values were almost identical.
The investigation and application of computer-numeric-control (CNC)-based ultra-high pressure water jet technology used in the field of wood processing have been paid increasing attention. In order to further optimize the technique of processing parameters in wooden crafts processing, medium density fiberboard (MDF) and solid wood of Italian poplar (Populus euramericana cv.) were taken as he experimental materials. The orthogonal experiment method was applied and the influence of several processing parameters including sand regulating speed, air-dry density, water jet pressure, feeding speed and target distance was considered to analyze the surface roughness. The water jet experiments were conducted based on the patterns designed by AutoCAD software with aid of numerical control working system. By the measurement of surface roughness and calculations, the influence of each processing parameter was investigated and the optimal scheme was then proposed. This work could provide optimization of processing parameters to the manufacturing of wooden crafts including fancy wood floors, indoor decorative boards of timber structure and mahogany furniture et al., which has high application value and practical significance.
This article deals with determining the effect of different degrees of thermal modification, different cutting speeds (20, 30, 40 m. s-1), different feed rates (4, 8, 11 m. min-1) and different rake angles (15, 20 and 25°) with a 1 mm layer of removed material, on the quality of the surface of the workpiece using the mean arithmetic variation of the waviness profile „Wa“. The release was secured by setting the ruler and firmly holding it in the desired position. The ruler so configured was all the time to milling all the setting options.The article evaluates the process of planar milling of natural and thermally modified oak wood (Quercus cerris). For the evaluation, the samples were thermally modified by the Thermowood process at a temperature range of 160-210°C. The quality of the treated surface was evaluated after the planar milling process. The results obtained from this research show that by increasing the cutting speed during the machining of thermally modified and natural oak wood, we achieve better values of the mean arithmetic deviation of the waviness profile. The values of the monitored characteristic can also be improved by lowering the feed rate and selecting an appropriate rake angle. Thermal modification…
At room temperature, on condition that the die be within temperatures of 200 - 300°C biomass briquette production made from sawdust (S) and bamboo powder (B) was conducted by a briquette extruder using post-heating method, fibre with steam explosion poplar fibres used as additive. As observed through the microscope, fibres as additive has the micro-mechanism of promoting mechanical properties of biomass briquette during densification. For verifying the feasibility and effect of fibre as additive, BBD experimental design was macroscopically adopted to compare the indicators of surface quality, relaxation density, maximum radial compression pressure, and hydrophobicity. Response surface model was used to deduce the reasonable heating temperature range for exploring the suitable condition of fibre as additive. The result showed that fibre as additive has apparent effect on briquette densification of sawdust and bamboo powder within a given temperature range. Through microscopic observation, it was found that fibres acted as solid bridges which played a positive role in densification in the heating temperature of 200∼250°C. At the temperature of 240°C, the fibres started to be carbonized. And within the temperature range of 250-300°C, the carbonized fibre mainly acts as lubricant between the briquette and the channel surface of the die.
The aim of this paper was to compare the tree-ring width measurement results obtained using standard medical CT scanner Light Speed VCT 64 with the results obtained from industrial CT scanner GE phoenix v|tome|x 240 during dendrochronological dating of a historical wooden sculpture. The examined object was a polychrome wooden sculpture of Madonna, which was of historical value – that is why equipment enabling non-destructive measurement of tree-ring width for dendrochronological dating had to be used. The sculpture was made of ring porous English oak wood (Quercus robur), which is very easy to measure. There are also standard chronologies available for this material for the area of the Czech Republic to be used for absolute dendrochronological dating. During the first stage of the research, an available CT scanner designed for medical examination of human tissue was used; then the object was measured again using an industrial CT scanner where better results could be expected thanks to higher image resolution. This paper compares the quality of images from both scanners and the results of tree-ring width measurement from the output of the two CT scanners. The re-sults successfully document the possibility of obtaining images of sufficient quality to measure the grow…
Consumers’ visual perception towards the product’s appearance can largely affect their preference and purchase intention of the product. Recently, the cardboard product, as a kind of environmentally friendly product, is becoming more and more popular in the market. Therefore, understanding the perception of consumers’ visual evaluation toward different cardboard products is crucial for cardboard product design. This study used eye-tracking technology and subjective evaluation together to investigate people’s visual perception evoked by different cardboard products. Nine different cardboard products’ pictures chosen from the internet were divided into three different types and three different assembly structures. Participants were then asked to observe those pictures when their eye movement behaviors were recorded by an eye tracker. Additionally, a questionnaire about the participant’s fondness and purchase of those cardboard products were filled out after the eye-tracking test. Consumers spent less average fixation duration on the cardboard product with more usability and more familiar form to evaluate their appearances. And stronger fondness and purchase intention of those kinds of cardboard products were showed in consumers’ visual perception. The exploring of the eye movement measurement on the visual perception can provide an accurate method for designers to better understanding the consumer’s fondness and purchase intention…
WOOD RESEARCH Volume 63, Number 2
Wood is a natural composite material with a complex structure. Its mechanical properties are mainly due to the cell walls. In order to investigate the relationship between mechanical properties and chemical composition of wood cell wall. Nanoindentation and Raman imaging were used to characterize the longitudinal mechanical properties and chemical composition distribution of wood fibers of three years old fast-growing poplar (Populus×euramericana cv. ‘74 /76’) during the growing season at different times. The results were showed that the content and distribution of cellulose and lignin are closely related to the mechanical properties of wood fiber cell walls, especially the cellulose for the longitudinal elastic modulus and the lignin for the hardness of cell walls. It was also demonstrated that the longitudinal elastic modulus and hardness of the secondary wall 2 layer (S2) were strongly correlated to the micro fibril angle (MFA) and crystallinity of cellulose during the active phase.
Eucalyptus pellita has been posited as a primary raw material in Indonesia due to its fast growth. In some areas, however, trees with heart rot were found. Thus, the wood with heart rot was analysed chemically both in sound (sapwood, outer heartwood, inner heartwood) and degraded parts (heart rot-affected wood/HRAW). The results revealed that there was a different trend in the wood chemical composition between bottom and centre parts. In bottom parts, wood with bigger diameter of heart rot, the slight changes in polysaccharides and lignin amounts was observed in HRAW compared to sound wood parts. On the contrary, comparatively high lignin and low polysaccharide levels in HRAW were measured in centre parts. HRAW was also characterized with high content of inorganic materials and high pH values but low in extractive content, mostly ethanol soluble extractives or its polar fraction. Increasing of phenolic contents was more pronounced in HRAW of lower part than that of upper of the stem. The difference trend of chemical composition between bottom and centre parts suggesting the cause of heart rot could be several wood degraders.
The wood-destroying fungi traditionally were separated from one another primarily on a basis of their sporocarp and/or strain morphology. Their diversity and simple macro- and micromorphology of fungal structures have been major obstacles for more rapid progress in this regard. However, over the past two decades, there has been substantial progress in our understanding of genetic variability within traditionally recognized morphospecies. In this study we have overviewed genetic variation and phylogeography of macrofungi, which are important destroyers of wooden materials indoor of buildings. Several morphologically defined species of these fungal destroyers (Coniophora puteana, C. olivacea, C. arida, Serpula himantioides) have been shown to actually encompass several genetically isolated lineages (cryptic species). The protective efficacy against cryptic species within traditionally recognized morphospecies through laboratory tests (EN 113) and field trials (EN 252) might be sufficient to better prognosis of decay development in wooden materials for hazard assessment and for proper conservation and management plans.
The dynamic and damping properties of nine different wood-based bio-composites at varying volume fraction of Corn starch (CS), methylene diphenyl diisocyanate (MDI), microcrystalline cellulose (MCC), processing time and pressure have been studied. The samples used for the study consisted of southern yellow pine particles with 2% Corn starch (CS), 4% methylene diphenyl diisocyanate (MDI); 4% CS 4%MDI; - 4% MDI; - 2% CS 2% MDI; - 4% CS 4% MDI; - 2% microcrystalline cellulose (MCC) 4% MDI; - 4%CS2% MDI; - and 1% MCC 4% MDI; - (all on a solids basis). The panels were manufactured using a Dieffenbacher hot press at a temperature of 185oC. The dynamic and damping properties were determined using hammer excitation vibration technique. The responses were obtained from frequency and time domain for the fundamental natural frequency (fn), and the results obtained were consistent. The panel manufactured with 4% MDI and formed at relatively high pressure (10.5 MPa) had the highest average storage modulus (E'), and this shows that increasing manufacturing pressure and density of material contributed to the high elasticity of the material. The panel produced with 2% CS and 2% MDI had the highest damping ratio (ξ) and Loss factor (η) when compared…
Rolling shear modulus (GR) and strength (fR) of the cross layers are decisive mechanical properties in cross-laminated timber (CLT) plates. The influences of macro characteristics, such as annual ring orientation, distance to pith, and presence of pith on the rolling shear properties of fast-growing poplar boards were evaluated throughout this study. It were found the presence of pith had significant influence on the rolling shear properties of poplar board. Distance to pith and annual ring orientation both had effects on the rolling shear properties jointly. The rolling shear properties increase with the increase of distance to pith. The mean rolling shear modulus and characteristic rolling shear strength values of the poplar wood were determined to be 177 MPa and 2.24 MPa, respectively, which indicates a great potential of using poplar wood as the cross-layers in CLT.
The paper presents the results of the research of the bending modulus of elasticity of some 700 year old subfossil elm wood (Ulmus minor) retrieved from the Sava riverbed (Bosnia and Herzegovina). The subfossil elm wood is very rare to find and is highly appreciated in this form for its beautiful appearance and specific mechanical properties. Adult elm trees are nowadays also very scarce in natural forest stands of SE Europe, due to the invasion of the Dutch elm disease (Ophiostoma novo-ulmi Brasier) some fifty years ago. The bending MOE was determined in the longitudinal direction and the angles between the direction of load and the annual growth ring orientation were 0°, 45°, and 90°. The obtained values of the bending modulus of elasticity are within the range of those obtained for a recent elm, which shows that numerous centuries spent in anoxic aquatic conditions have not affected the investigated property of subfossil elm. The study showed that the annual growth ring orientation significantly affects the MOE of subfossil elm wood in the longitudinal direction. The highest values were obtained at the angle of 45° (L45°), and the values for L0° and L90° are very similar. The variability and heterogeneity…
Steady-state heat transfer performance of wood frame wall is an important index to assess its energy efficiency. In order to study the factors that affect the heat transfer coefficient of wood frame wall, the method of improving the thermal insulation property of the wall was studied. In this paper, 12 wall specimens with different structures were manufactured, and the effective heat transfer coefficient was measured by the hot box-heat flow meter test method. The reliability of the theoretical calculation value of thermal resistance was verified by the experimental value. The results showed that the moisture content of Spruce-pine-fir (SPF), insulation materials, spacing and thickness of studs had influence on the heat transfer coefficient of walls. The effective heat transfer coefficient values of three walls ranged from 0.325 to 0.398 W•m-2•K-1, which met the thermal level It of the severe cold area. The linear correlation between the theoretical calculation value and the test value was up to 0.9587, effective thermal resistance value of wood frame wall can be estimated by calculating without extra experiment.
The aim of this study was to determine the drying time of firewood under the climatic conditions of the Czech Republic to decrease the moisture content to an acceptable level for combustion (under 20%). The effects of log size, outdoor/indoor trying and wood species were evaluated.
The aim of this work is the probabilistic modeling of the failure of Lovoa trichilioides and Triplochiton scleroxylonspecies. A general presentation of the wood while focusing on the Weibull distributions was carry out. Parameters of the Weibull distribution for each of the materials were determined. We remark that when the Weibull shape parameter is small, the failure stresses dispersion is greater and the Weibull scale parameter increase or decrease depending on the stress. It is also shown that Lovoa trichilioides exhibits a high dispersion of breaking stress in contrast to Triplochiton scleroxylon. A comparison of the experimental data with the statistical laws allowed us to show that the three-parameter Weibull distribution better models the failure than the normal and the two-parameter Weibull distributions. The studies of variance prove that the failure stresses of Triplochiton scleroxylon vary less in comparison with that of Lovoa trichilioides.
In this research, the influence of various factors on the performance of the melamine bamboo cellulose gum is investigated by orthogonal test method, with the pressing temperature, pressing time, the added amount of cellulose gum, melamine dosage as factors. And analyze the samples by Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA), DTG, etc. The amount of melamine is the main factor affecting the quality of bamboo composite material and its physical and mechanical properties, it has a significant impact on MOR board, internal bond strength, elastic modulus and other properties; cellulose gum is a secondary factor affecting performance. The results showed that cellulose gum ratio of 5 %, ratio of melamine of 2.5 % and the hot press time of 9 min provided the optimum conditions for hot press.
Wood chips used for chemical pulp must be of relatively uniform size. The penetration of the pulping chemicals and thus the cooking time, is considerably determined by chip length. The clearance angle (pull-in angle) is a significant parameter of the knife positioning in the disc chipper, that affects the length of the chips." In many production plants, this angle is wrong set depending on the diameter of the chipped wood. This causes problems in obtaining the appropriate length of the chips. The disc chipper in one of the industrial plants in Poland was investigated because it produced chips with smaller lengths from the assumed. This also included the numerical calculations to optimize the clearance angle. In the disc chipper, the variability of the clearance angle (α) along the cutting edge of the knife (helical knives) gives the possibility of improving the quality of the wood chips. Simulations to determine the variability of the clearance angle on the radius of the disc of chipper assuming the continuity of cutting wood in the chipper was also performed.
Wood flour-polyurethane composites (WPC) with ammonium polyphosphate (APP) and ferric oxide (Fe2O3) were prepared to research the cooperative influence of smoke suppression and fire resistance. By the methods of cone calorimeter test (CCT), smoke density test (SDT), thermogravimetric analysis (TG), limiting oxygen index (LOI), field emission scanning electron microscope (FE-SEM) and Fourier transform infrared spectroscopy (FTIR). Remarkably, Fe2O3 has significant improvement on heat release rate (HRR), total heat release (THR), smoke factor (SF), and total smoke release (TSR) of the APP/WPC.SDT implied that Fe2O3 played a positive role during burning and there is a synergistic effect of smoke suppressing for Fe2O3 on APP/WPC. The LOI results showed that compared with samples without flame retardant, adding Fe2O3 improved the LOI value of WPC. TG indicated that Fe2O3 and APP played an effective role in the course of thermal degradation of WPC. And the SEM and FTIR showed that Fe2O3 and APP played a role in ameliorating the residual carbon structure.
In the presented study the injection mold equipped with the test apparatus were used to determine the viscosity curve of wood – polymer – composite (WPC). During the test the polymer temperatures, flow rates and pressure data measured inside of mold cavity were recorded. In addition the pressure – volume – temperature (PVT) characteristic of this composite was determined using the capillary rheometer. The determined properties were used in numerical simulations of injection molding process of WPC. The results were verified on the basis of pressure profiles measured in the mold cavity during experiment. The simulation was performed using the Autodesk Moldflow Insight 2013 commercial code. The calculated and measured pressure profiles were compared.
The effects of process parameters (adhesive spread, press time, and applied pressure) on the gluing performance of engineered wood flooring bonded with emulsion-polymer-isocyanate (EPI) adhesive were studied. The results showed (shear strength and aging test) that the major factors were adhesive spread and press time. The optimized parameters for best gluing performance of engineered wood flooring were 160 g. m-2, 14 s, and 60 s for adhesive spread, heat time, and press time, respectively, within certain ranges.
In this study, the samples obtained from European hop-horn beam (Ostrya carpinifolia Scop.) wood has been subject to cutting with circular saw, planing with a thickness machine and sanding with a caliber sanding machine (with no: 80 sand). After the specimens were processed in the machines in radial and tangential surfaces, their surface roughness values (Ra, Ry, Rz) have been determined in accordance with the ISO 4288 standard. According to the statistical results, the lowest roughness values have been achieved with the thickness machine. Similarly, the roughness values of tangentially cut surfaces have been found to be lower than the radially cut surfaces.
The superhydrophobic wood surface was fabricated in this study by impregnating oven-dry poplar (Populus cathayana Rehd.) samples with a silica/silicone oil complex emulsion (SSOCE), mainly composed of two silicone oils(hydroxy silicone oil and hydrogen silicone oil) and two different sized silica particles (micron and nano scaled, respectively). Different concentrations of the complex emulsion (5%, 10%, 20%, 30% and 40%) were used and their effect on static contact angles (CAs) and surface free energy (SFE) of wood were investigated. The chemical and morphological changes of modified wood surface were characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS). The superhydrophobic wood surfaces were manifested by the water CA of about 154.8° on the transverse section, 151.3 °on the tangential section and 150.2° on the radial section, respectively. It was confirmed that silicone oilsin the complex emulsion formed a silicon resin filmand uniformly attached on the wood surface, with silica particles in micron and nano scales helped to make the surface rougher.
WOOD RESEARCH Volume 63, Number 3
The paper deals with antibacterial effect of silver and zinc-oxide nanoparticles in acrylic coatings applied at treatment of commercial wooden composites - particleboard and medium density fibreboard. The silver nanoparticles usually better suppressed the activity of the Gramnegative bacterium Escherichia coli and the Gram-positive bacterium Staphylococcus aureus already at lower concentrations (0.04 – 0.2 mg Ag/100 g of coating) as the zinc-oxide nanoparticles used in 100-times higher concentrations (4 – 20 mg ZnO/100 g of coating). Both types of applied nanoparticles at higher concentrations had a more apparent efficiency against E. coli comparing to S. aureus.
This paper presents a study on the effect of hygroscopicity of fire retardant on the hygroscopicity of fire retardant materials (bamboo chips). The results showed that the hygroscopicity of fire retardant and fire retardant bamboo chips increased with increasing fire retardant concentration, and the suitable range of fire retardant concentration is 20- 30 %; the hygroscopicity of fire retardant and fire retardant bamboo chips increased with the increasing of drug loading rate of fire retardant bamboo chips, and the suitable drug loading rate is 10.2 %; the hygroscopicity of fire retardant bamboo chips increased with the increase of the hygroscopicity of fire retardant, and the hygroscopicity of fire retardant bamboo chips is smaller when treated with the fire retardant whose water absorption rate less than 18 %.
Longitudinal compression makes natural wood easier to bend. The relaxation after compression results in much improved bending properties. During a bending test, the maximum deflection increases with the relaxation time, while the needed force to reach the same deflection decreases, similarly to the modulus of elasticity (MoE). The modulus of rupture (MoR) of the compressed wood does not change considerably compared to the untreated wood, except at the long-time relaxed samples. The ideal relaxation time is 1 minute. After that the change of the important properties slows down. Of course with special demands, the relaxation time can be also very long. In this case the process leads to a wood sample with pronounced flexible properties. Samples were left to rest between normal circumstances for 1 day, but this resting period did not have a significant effect on its mechanical properties.
This study describes the dynamic accumulation of xylem cells of the fast-growing Populus×euramericana cv. ‘74 /76’ during the growth phase by the methods of microscopy analysis and computer simulation technology. In order to show a more intuitive accumulation and dynamic variation process of cells in different periods, the computer simulation software was used to simulate the accumulation process of cambium and xylem cells according to the data of the accumulation and anatomical characteristics. The dynamic accumulation process of the xylem cells was visually displayed by the computational simulation technology during the active period.
This study investigated the physical, chemical, and termite resistance characteristics of fiberboard made from the trunk fiber of five bamboo species (Giganto chloaapus, Gigantochloa atroviolacea, Giganto chloaatter, Dendrocalamus asper, and Bambusa vulgaris) and its suitability as a construction material. Five types of fiberboard with a target density of 0.8 g. cm-3 were prepared by using a hot-pressing system at a temperature of 180°C for 15 minutes. Fiberboards were examined for the bonding strength, lignin content, and morphological characteristics. Termite resistance characteristic of fiberboards was performed by three-week laboratory feeding trials against Coptotermes formosanus Shiraki and Incistermes minor Hagenas described in Japanese International Standard (JIS) K. 1571. The results showed that the strongest bonding characteristic was B. vulgarisfiberboard, followed by G. apus, G. atroviolacea, and G. atter. The highest lignin content presented in G. atter (29.23%), followed by G. atroviolacea (28.78%), D. asper (26.60%), G. apus (26.48%), and B. vulgaris (23.87%). The lowest weight loss of bamboo fiberboard after termites’ assay was D.asper (7%). In conclusion, the fiberboard made from the fiber of bamboo trunk waste hasthepotency as a promising building material. However, alltypes of bamboo fiberboard would require additional protection for applicationin the area with a high number of termite…
Although researches have been carried on the bio-chemical deterioration of archaeological wood, still the degradation of archaeological wood is so complicated to fully understand. One essential question is how archaeological wood of large volume would degrade from surface to deep inside and why. The recently unearthed outer coffin of Marquis of Haihun, buried for over 1800 years, gave us a great opportunity to investigate this question. The degradation features were analyzed with methods of optical microscopy, Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), viscosimetry, and determination of physical properties of wood. The results, including the microstructures of wood fibers, wood components, degree of polymerization and crystallinity of cellulose, and shrinkage of wood, unanimously show that the sapwood of the board is worst degraded, the surface layer of the heartwood is degraded to a higher extent than the inner part, and it tends to degrade more easily along the axial direction.
The paper describes a process for the preparation of fibre from waste wood particleboards (PB), oriented strand chipboard (OSB) and medium density fibreboard (MDF). The purpose of recycling of agglomerated wood materials is to reuse them for the production of fibrous materials. The agglomerated materials disintegrated after the initial destruction were further processed under the specified conditions with respect to the moisture content, their type, adhesive used, and properties of final particles - wood chips. The obtained wood particles were characterized by the fractional composition of chips. The resulting chips were mechanically defibred with subsequent characterization of fiber obtained for its reuse in the manufacture of MDF. A quantity of formaldehyde released into the water when cooking waste MDF and PB was set up depending on the cooking time. Residual level of formaldehyde is the main chemical load that determines the amount of waste material that can be reused for production of new panels based on ureaformaldehyde adhesives.
The aim of this study to develop an eco-friendly wood stain and to determine the adsorption and desorption on surfaces. In this context; plant dyestuff was extracted from the red beetroot by using ultrasonic assisted method and applied to wood blocks of Turkish oriental beech, Scots pine, oak, and walnut with immersion (classic) and ultrasonic-assisted immersion methods. As mordants, ferrous sulphate, aluminum sulphate, copper sulphate, and vinegar were chosen. In the study, the effect of such parameters as the medium pH (3, 7 and 9), temperature (22°C and 40°C), velocity of agitation (10 and 30 rpm) in leaching was investigated. As a result of experiments; red beetroot extracts performed good desorption, vinegar and copper sulphate were reduced the best desorption on surfaces. Ultrasonic-assisted method was not affect the leaching performance positively, but general leaching results showed that red beetroot can be used for wood surface stain and they can be alternative to chemical dyes.
In order to study the cutting performance of TiC reinforced Al2O3 ceramic cutting tools in milling high density fiberboard, the effects of cutting parameter on the cutting forces, tool wear and cutting quality were investigated. Under the condition of same average chip thickness, feed per tooth and geometry angles, firstly, the change rate of maximum cutting forces were higher than that of average cutting forces at two different cutting speeds, and the cutting forces at high speed cutting was less than that at low speed cutting. Secondly, the flank wear at high speed cutting was more pronounced than that at low speed cutting, whose abnormal wear were pull-out of grain, cracking, chipping and flanking. Thirdly, the machining quality at high speed cutting was better than that at low speed cutting. Fourthly, the tendencies of cutting forces, tool wear and surface roughness relative to cutting length were similar, but the change rates were different, especially at the initial stage. Finally, high speed cuttingare plausible to use in HDF processing, which not only improves machining quality, but also promotes production efficiency.
In this study, usage of mono ethanol amine (MEA) as an organic reagent was considered in pulping of Milkweed compared with alkaline non-friendly pulping methods including Kraft and Kraft-AQ and soda-AQ. In this case, monoethanolamine was added in various ratios i.e. 100, 75, 50, 37.5 and 25% in replacement with water (MEA-water pulping). Besides, anthraquinone was added in parallel with MEA-water treatments (MEA-water -AQ ) and its effect on pulp properties has been considered. The results indicated that replacement ratio of 75/25, 240 minutes of retention time and with0.1% usage of anthraquinone showed the optimum conditions based as yield and kappa number of the pulp samples. Moreover, at the same degree of delignification, the MEA pulps showed about 15-20% higher yield based on raw material. Total unbleached MEA pulp yield is very high, ranging between 48 to 54% with kappa number of 58. For Kraft, the yield varied between 38 to 43%.
The development of wood use as a renewable raw material for construction caused that can be also seen as the construction of bridge structures, which have to withstand the environment. It is a modern construction using LLD or replicas of historical buildings using RD. Many of these constructions, despite impregnation, are struggling with biological pests that greatly reduce their durability. Revealing of the most dangerous ones is complex and usually cost such amount of money. Diagnostic methods and their results are different. The article deals with the comparison of the diagnosis methods of wood decaying fungi from the family of Gloeophyllaceae to the real construction.
A technique to improve paint utilizing efficiency of wooden board during electrostatic spraying process was proposed. An experiment was carried out for verification of its feasibility. A finite element model for electric field between spray gun and wooden board was built by ANSYS software. Experimental results show that paint weight per square meter of wooden board surface after electrostatic spraying is increased significantly when the technique is used. Simulation results show that the electric field intensity between spray gun and wooden board is increased obviously when the technique is used.
Paraserianthes falcataria is fast growing species that considered being potential lumber for construction application. The aim was to evaluate the effect of year rotation of harvesting on quality of Paraserianthes falcataria wood for construction application. Nine trees of Paraserianthes falcataria with harvesting rotation of 5, 7, and 9 years, were harvested from the private forest. Moisture content, specific gravity, shrinkage, MOE, MOR, and compressive strength parallel to grain were measured for wood quality parameters in accordance to JIS Z 2101. Durability test were conducted against dry wood termite (Criptotermes cynocephalus Light). The results showed that year harvesting of Paraserianthes falcataria influence significantly on specific gravity, and compressive strength parallels to grain. Paraserianthes falcataria wood is classified into strength class III-IV, which is properly used for light construction. To obtain optimum quality for construction purposes, Paraserianthes falcataria tree is recommended to be harvested in minimum harvesting rotation of 7 years.
The chair joined by oval mortise-and-tenon was taken as a case. Then influences of two adjacent sides (side A and side B) stretcher positions on mechanical properties of chairs, including ultimate loading capacity, stiffness and strain distributions, were investigated through using experimental and numerical methods. Firstly, two factors and three levels experiments were conducted and analyzed by Finite Element Method (FEM) . The results showed that ultimate loading capacity of chairs decreased firstly and then increased with the growth of the height of stretchers positions. In addition, the stress concentration occurred at middle of side rails and joints of side rails, especially at the side B, while the stress at the middle of the leg was minimum. Besides, the higher the stretcher position of the side A was, the more harmonious the stress distributions of chair was, and the higher ultimate loading capacity and stiffness were. Moreover, the results of FEM were well consistence with those of experiments, and the errors were within 10%. Secondly, two factors and five levels numerical analysis was conducted to optimize the stretcher positions of chair by the FEM, and the results showed more boadly that the best stretchers positions of chair owning the highest…
The study presents results of hydrophobic properties examination of Scots pine wood treated with a propolis extract and two propolis-silane formulations determined by contact angle analysis and water uptake test. From contact angles data the surface free energy and its shares as well as the work of adhesion were calculated and described in this paper. Treatment with the ethanolic extracts of propolis (EEP) and the propolis-silane formulations a water repellent property of treated wood when compared to control wood. Addition of silicon compounds to the propolis extract caused decreased of the water uptake and increased of the contact angle value of treated wood. The most effective hydrophobic effect was obtained using the impregnation with the formulation based on EEP and organosilanes: vinyltrimethoxysilane (VTMOS) and tetraethyl orthosilicate (TEOS).
First, this article introduces the natural properties of wood. Wood not only has the unique wood texture, rich colours, but also has changeful shape and unique cultural attributes, what is why wood can be widely used in many fields. Secondly, the article briefly describes natural and cultural attributes, and analyzes the cultural connotation embodied in product design. The dual properties of wood meet the material and spiritual needs of people. Finally, by introducing the two cultural and creative products of writer designs to indicate the development of cultural products is a traditional material as well as the new era of the spiritual needs of the perfect combination of the way. It also plays a decisive role in reflect the wood for promoting cultural and creative product design.
WOOD RESEARCH Volume 63, Number 4
China is rich in bamboo resources. But there has been a huge gap in timber supply. The most effective solution to eliminate the existing timber supply gap is to carry out the industrialization of bamboo so that the bamboo resources can be fully used. Bamboo is full of nutriments, but it is perishable and difficult to store. Usually bamboo is vulnerable to mildew and insects. Therefore, it is of great significance to research bamboo mold corrosion protection technology for the high-efficient development of bamboo resources. The antifungal activity of different solvent extracting tests were conducted from Pinus elliottii needles (hexane extract(W1), ethyl acetate extract (W2), anhydrous ethanol extract (W3) and water extract (W4)) in white-rot fungus Coriolus versicolor and brown-rot fungi Gloeophyllum trabeum, Polyporus vaporaria Fr. The tests concequence verified that Pinus elliottii needles extracts W1 and W2 have better inhibitory effect on white-rot fungus Coriolus versicolor and brown-rot fungi Gloeophyllum trabeum, Polyporus vaporaria Fr, which indicated that W1 and W2 had possibility to develop as natural fungicide. Further analysis of indoor anti-corrosion of bamboo indicated that W1 and W2 played the best role in bamboo antiseptic effect. The latest research manifested that W1 and W2 have potential to be…
The aim of the research was to perform the medium-scale fire tests of two alternate samples of the log wall, using the radiant heat source. The radiant heat source consisted of a ceramic radiation panel with a maximum power of 50.5 kW.m-2 and a maximum temperature of 935°C. The samples varied by their geometric shape and the different design of the groove, which was sealed with glass mineral wool. A better result was achieved by a round wood sample with the circular section, which also resisted to high temperatures in the place of the groove and did not start burning with flame. The sample of the squared log elements started to burn with a flame. Temperature measured in the groove was much higher than in the first case.
Wooden perforated plates are used to control noise and optimize the indoor sound environment. In the paper, the effects of structure factors on the sound absorption properties, such as the absorption peak, resonant frequencies, and frequency bandwidth, were analyzed using the impedance tube transfer function method and SAS (Data analysis software) significant analysis. Experimental results showed that with the thickness of the medium density fiberboard (MDF) perforated plate increasing from 10 to 20 mm, the resonance absorption frequency shifts to the lower frequency. The depth of hole increased, the absorption peak reinforced. With the pore size increased, the resonance absorption frequency reduced and meanwhile the resonance peak absorption coefficient shrunk. The resonance frequency moves toward the high frequency direction and the sound absorption coefficient decreased when the perforation rate was increased from 3.14% to 7.07%. After increasing the air gap thickness from 25 to 100 mm, the resonance absorption frequency reduced and the sound absorption bandwidth remained relatively constant as the acoustic impedance of the MDF perforated plate did not vary in spite of the variation in the air gap thickness. But the absorption coefficient decreased. This paper may provide a certain theoretical basis for wooden perforated plate design and…
In this study, investigation of the thermal properties of Oriental beech (Fagus orientalis L.) wood samples treated with 1.50 and 3.00% aqueous solutions of SiO2 and Al2O3 nanoparticles were performed by using thermogravimetric analysis (TGA), differential-thermogravimetric (DTG), and differential-thermal analysis (DTA) under argon atmosphere. Thermal degradation of SiO2 and Al2O3 nanoparticles treated Oriental beech wood could be separated in three district regions. These regions could be called as drying, pyrolysis, and charring. Our results showed that Al2O3 and SiO2 nanoparticle treatment increased residual char yield of Oriental beech wood samples. The highest residual char yield was obtained for wood samples treated with 3.00% Al2O3 nanoparticles. Moreover, higher concentration levels resulted in lower Tmax values, higher Ti values and higher char yield of Oriental beech wood.
There are simplified and advanced design methods for the determination of the mechanical resistance of timber structures in fire. The simplified methods have some limitations and in case it is not possible to use the simplified methods, it is necessary to use the advanced ones. These advanced design methods can be analytical or numerical. This contribution deals with the determination of the one-dimensional charring rate depending on time by advanced calculations, focusing on the influence of different input parameters, with the results of an experiment being presented for comparison. The aim of this paper is to show that despite the suitability and conservativeness of the method according to Eurocode 5, there are various cases (different moisture, wood species etc.) when it is necessary to perform numerical or analytical analyses without the possibility to apply standard input parameters. Therefore, this contribution compares individual methods for finding of the most appropriate one.
The tensile and bending strength of double wood dowels in medium density fiberboard components was tested by using experimental method which was conducted to define the influence of dowel diameter and curing time on tensile and bending strength of T-shaped and L-shaped double wood joints. The results showed that the dowel diameter and curing time have a great effect on the tensile and bending strength of T-shaped and L-shaped double wood joints. The obtained optimum technical parameters were respectively as follow: dowel diameter was 10.00 mm for tensile strength of T-shaped joints, dowel diameter was 10.00 mm for bending strength of T-shaped and L-shaped joints, and curing time was 168 h for bending strength of T-shaped and L-shaped joints. The relational expression between dowel diameter R and the tensile strength P was obtained in P= 159.7R+11.05, the relational expressions between dowel diameter R and the bending strength P were obtained in P= 30.7R-58.21 and P= 25.48R-41.04 for T-shaped and L-shaped double wood joints, respectively. Moreover, the relational expression between curing time T and the bending strength P in the P= -0.003T2+0.683T+164.1 and P= -0.003T2+0.746T+132.0 for T-shaped and L-shaped double wood joints, respectively.
This work investigates how wood modification with silicon dioxide affects its selected physical and mechanical properties and resistance to moulds. Silicon mineralization can improve some of the technical properties of wood and extend the service-life of wooden structures. Silicon, which is contained in inorganic and organic-inorganic substances that are used for artificial wood mineralization or is the main component at natural wood mineralization, was used in the form of colloidal silicon dioxide and its various concentrations for pressure impregnation of beech (Fagus sylvatica) and Silver fir (Abies alba) wood samples. Following, physical, mechanical and biological properties of such modified woodswere tested together with waterlogged fir wood stored in water over a long period. Silicon-dioxide did not significantly improve properties of beech and fir woods, probably due to the hypothesis, that none covalent bonds between the silicon and the OH- groups of cellulose, hemicelluloses or lignin could be created in the cell-walls of the silicon-modified woods.
Magnesia-bonded Wood-Wool Panel is a kind of environmentally friendly inorganic material with wood-wool as matrix materials, and magnesium oxychloride cement (MOC) as binder which is also a kind of porous material with nice sound absorption property. In this study, through single factor experiments, it was found that The thickness of the panel, molar ratio of MgO/MgCl2/H2O, wood-wool length influenced material sound absorption performance of the panel significantly. The thickness of the panel was the most significant factor affecting the panell’s sound absoption property, while the effects of density of the panel and weight ratio of magnesia to wood were not significant. The optimal factors were obtained through orthogonal experiments: Thickness of the panel 25 mm, molar ratio of MgO to MgCl2 to H2O 5: 1: 10, density of the panel 0.65 g.cm-3, weight ratio of magnesia to wood 1.25, wood-wool length 200 mm.
Three properties of dissolving pulp namely lignin, viscosity and the α-cellulose were investigated. A laboratory experiment for the dissolving wood pulping process was conducted on nine Eucalyptus genotypes: Edunnii, Esmithii, Egrandis, Macarthurii, Emearnsii, Enitens, GCG438, GUA380 and GUW962. Repeated measurements were taken at each of the six processing stages for the changes in lignin, viscosity and the α-cellulose. A response surface approach was used to select the best genotype for each property and further application of desirability analysis to identify the genotype that simultaneously gives the best results for the three properties. The predictive models and associated statistical tests proved that all the nine genotypes were capable of producing the optimal results (>95.55% α-cellulose) although a few were at the thresholds of the feasible region. The optimisation process also revealed that the genotype Emearnsii possesses the most desirable properties for the α-96 cellulose product output and Enitens consistently produces results within the desired range. The use of simultaneous desirability functions indicated that the overall product quality characteristics for lignin, viscosity and the α-cellulose can be improved by steadily excluding the most resistant genotypes to lignin reduction, especially Edunnii and Esmithii.
Deinked pulps for hygienic paper production were bleached with hydrogen peroxide and sodium dithionite in single and two-stage bleaching. The brightness gain of high brightness deinked pulp in the peroxide stage was 5.7% ISO and of low brightness 4.4% ISO. In sodium dithionite stage, the brightness gain of high brightness deinked pulp was 4.0% ISO and of low brightness deinked pulp 3.8% ISO. The two-stage oxidative-reductive bleaching sequence resulted in an increase of brightness by 9.7% ISO for high brightness deinked pulp and by 9.1% ISO for low brightness deinked pulp. Brightness gain in the two-stage reductive-oxidative bleaching sequence was 6.7% ISO for high brightness deinked pulp and 5.6% ISO for low brightness deinked pulp. The coordinate b* value and yellowness of deinked pulps decreased in sodium dithionite bleaching stage more than in hydrogen peroxide stage. The two-stage oxidative-reductive bleaching sequence is more preferred than reductive-oxidative sequence regardless of the fibre composition. The tensile index and the tensile energy absorption index of deinked pulps slightly decreased after single-stage and two-stage bleaching sequences, their reduction in the peroxide stage was greater than in the dithionite stage. The fibre strength and fibre length characteristics of deinked pulps decreased after bleaching, while fibre…
Residues of agriculture and forestry are usually exploited as feedstock within pellet production for energy producing applications. Some variables such as moisture content and die temperature strongly influence this process. Bamboo powder was used as the experimental material to produce high quality pellet fuel in this paper. A series of experiments involving pellet production were conducted in different die temperatures and at different moisture contents by a newly-developed pellet extruder using a die heating production method. Unit density and densification pressure were tested with four levels of moisture contents (5, 10, 15 and 20%) at five levels of temperatures (40, 80, 120, 160 and 200°C). The surface quality of the pellets was investigated 6 months after the pellets had been produced. The optimum moisture content is around 10% and a suitable die temperature is 160°C to 200°C when producing bamboo pellets.
In this study, construction conditions of homogenous particleboard manufactured from mixing of poplar wood (Populus alba) slab, citrus branches and beech (Fagus orientalis) twigs have been investigated. The density of particleboard at three levels of 0.65, 0.7 and 0.75 g.cm-3, the amounts of resin at two levels of 9 and 11% and the amounts of pressing temperature at two levels of 160 and 170° C were considered. Increasing the density from 0.65 to 0.75 led to an increase in MOR, MOE and IB. By increasing the density, water absorption of particleboard decreased but its thickness swelling increased. By increasing the resin percentage the mechanical properties of particleboard improved, although this improvement was not statistically significant. Furthermore, by increasing the resin percentage the dimensional stability of particleboard improved partially. Not only did increasing the pressing temperature have any significant effect on the improving of mechanical properties of the particleboard, but also it has even led to a decrease in IB. Increasing the pressing temperature reduced the water absorption of particleboard in the short term (2 hours) while this increase led to a further increase in the thickness swelling of particleboard.
This article deals with the quality of the milled surface of board edges. The quality is evaluated using the Wa (mean arithmetic deviation of the surface waviness). The Wa was measured by two methods (contact and contactless). Form Talysurf 50 Intra was used for the contact method, and the LEXT 3D measuring laser microscope OLS4100 was used for the contactless method. The variable factors whose effect on the resulting waviness was determined were the machined material, milling cutters, cutting speed and feed rate. The boards used were medium-density fiberboard, medium-density fiberboard with single-sided lamination and spruce edge-glued panel. Three different cutters were used for the milling, all of which were made of sintered carbide, and one of them was coated (CrTiN). The cutting speeds were 20, 30, 40 and 60 m.s-1, and the feed rates were 4, 8 and 11 m.min-1. All the above-mentioned factors as well as their mutual interaction had an effect on the waviness. There was no significant difference between the two methods for determining the waviness. In terms of waviness, both methods are interchangeable.
Chemical composition, anatomical characteristics and cell wall structure of Ampelodesmos mauritanicus (Diss) and Stipa tenacissima (Esparto grass) fibers were analyzed. The results reveal the % (W/W) holocellulose content of Diss and Esparto grass was found to be 54.39 % and 51.8 %, respectively. Esparto grass had the greatest % (W/W) lignin content of 32.2 % while Diss had the last lignin content of 24.95 %. Estimation of %( W/W) extractives contents in Diss and Esparto-grass were observed to be 12.03 % and 13.5 % in that order. According to XRD data, Diss showed, as expected, a lower crystallinity index (CI) 52.5 % when compared to Esparto grass samples 55.2 %. The results of the thermal decomposition of natural fibers are shifted to higher temperatures with increasing the cellulose crystallinity. Based on the results of the chemical composition of Diss and Esparto grass, it was confirmed that straw is rich in cellulosic fibers and, therefore, a valuable raw material for the paper and manufacture industry.
Microfibrillar cellulose (MFC) samples from different agricultural resources and their wastes were characterized and compared in this study. MFCs were prepared from corn stalk, sunflower stalk, reed and sesame husk by two different methods. Hydrochloric acid (HCl) was used in Method 1, while formic acid (CH2O2) and sulphuric acid (H2SO4) were used in Method 2. SEM, FTIR, XRD and TGA analyses were conducted to determine the morphological, physical and thermal properties of the MFCs. The widths of the MFCs varied between 2.35 μm – 7.96 μm depending on the treatment methods and the raw materials. The crystallinity index of the lignocellulose increased after the chemical treatment, and the highest crystallinity index was found to be 82.0% for the sesame husk treated by Method 2. FTIR results indicate the presence of cellulose (~1640 cm-1), hemicellulose (1740 cm-1), lignin (1510 cm-1) and the other components in the MFCs. The TGA results show that the decomposition temperatures for the treated samples were higher than those for the untreated samples, indicating that the chemical treatments increased the thermal stability of the MFCs. As a consequence, it was seen that agricultural resources and their wastes can be an effective raw material in production of MFCs.
Eye-tracking technology was shown to have the ability to indicate human’s cognitive preferences toward objects. Using eye-tracking technology to study the cognitive preferences on different Chinese furniture style may have the potential to promote the furniture design from a novel perspective. Experiment was designed to test the differences of eye movement index (total fixation time, average fixation counts and average pupil diameter) within variables of gender, major and furniture styles. Participants were asked to observe two sets of different styles of Chinese furniture pictures on computer screen. Significant differences of total fixation time and average fixation counts were found between different furniture styles (p
WOOD RESEARCH Volume 63, Number 5
Chosen metals contents were analyzed in Norway maple (Acer platanoides L.) in bark, roots and wood samples collected from the polluted environment. Samples were gained from three cca. 40-year old trunks, which were grown on Krakowskie Przedmieście st., next to the St. Anna church in Warsaw, Poland. Wood of trunk and the main roots, as well as bark from butt-end section were also sampled. Contents of Ca, Mg, Mn, Zn, Fe, Al, K, Na and Sr were examined with the application of spectrometric methods. The results show that environmental pollution significantly influences the content of examined elements. The change of Na content is the most spectacular. Its content is hundred times higher, in wood and bark, as well as in the main roots, in relation tree from non-polluted environment, what is probably caused by urban environment salinity.
This study was conducted to investigate the properties of Persian oak (Quercus brantii Lindl.) wood, the most abundant tree species, harvested in the west and southwest regions of Iran. To the best our knowledge, there were no reported studies investigating the physical, chemical and biometrical features of Persian oak wood. For this purpose, 12 healthy trees in three diameter classes including 10-20, 20-30 and 30-40 cm were selected randomly and a disk was cut from each one at breast height. Results indicated that the highest basic densities are related to the diameter class 20-30cm (0.98 g.cm-3) and the lowest one at diameter class 10-20 cm (0.88 g.cm-3). The highest shrinkage was determined at oak wood samples from the diameter classes 10-20 cm (14.15%). Fiber length varied between 0.82 g.cm-3 (Dia. Class 10-20 cm, middle part) to 1.01 (Dia. Class 20-30 cm, bark). With increasing diameter, the cellulose content increased and the lignin content decreased while ash and extractive content was quite constant.
Southern yellow pine (Pinus sp.) wood cubes were vacuum-pressure treated with nano-SiO2 solution and different concentrations of ACQ/polyethylene glycol (0.5%, 2.5% and 5.0%) modified solutions. The effects of polyethylene glycol concentrations and nano-SiO2 addition on the water absorption, air drying shrinkage and moisture swelling stability of treated wood were investigated. The results showed that during the whole process of water absorption and air drying shrinkage, the better stability of nano-SiO2 modified ACQ treated wood could only be obtained with the ratio of 2.5% polyethylene glycol addition. However, nano-SiO2 and polyethylene glycol modification could take little effect on the moisture and water swelling resistance of treated wood with different treatments.
This study was designed to investigate color changes of heat treated and varnished Scots pine (Pinus sylvestris L.) and Oriental beech (Fagus orientalis L.) after 3 months of weathering. Heat treatment of Oriental beech and Scots pine wood was carried out by hot air in an oven for 1, 2, and 3 hours at 205, 215, and 225°C. After heat treatment, wood specimens were varnished using a polyurethane varnish (PV) and cellulosic varnish (CV). The results of study showed that heat treatment generally caused decrease of lightness of both wood specimens before weathering. In general, while heated and PV coated Scots pine and Oriental beech wood surfaces turned to reddish and yellowish, heated and CV coated Scots pine and Oriental beech wood surfaces turned to reddish and bluish after weathering. The total color changes of heated and varnished both wood specimens were lower than only varnished both wood specimens after weathering.
This work optimizes the parameters of ultrahigh-pressure water jet, with or without abrasives, for the cutting of Pterocarpus macarocarpus Kurz wood, a precious species. Parametric factors of cutting pressure, target distance and feed rate were analyzed with respect to the resultant surface roughness of the cuts on specimens using an orthogonal experiment. The optimal machining schemes were elected for water jets either with or without added abrasives based on microscopic evidences. The results showed that the impacts on the resultant surface-roughness of the factors with a given water jet, i.e. either with or without added abrasives, from the most to the least, are both in the order of water jet pressure>feed rate>target distance. Water jets with no added abrasives have lower cutting capacity, which was evidenced by the worse surface roughness of cuts resulted from rebound jet. Raising their kinetic energy, the probabilities of fracture from tearing would also rise, thus, inducing corrugation in the bottom with exacerbated overall surface roughness of cuts. Abrasive water jet has the feature of many ripples, decreasing the surface integrity of specimens. Therefore, to improve product quality of Pterocarpusma carocarpus Kurz wood, is to increase the portion that is smooth in the sections from…
The biomass generated from tree pruning or derived from the forest exploitations could be susceptible to chemical use and studies on chemical composition in tree branches are scarce. Therefore, in this investigation the biomass of the branches of six hardwood species (Alnus acuminata, A. jorullensis, Quercus candicans, Q. laurina, Q. rugosa and Symplocos citrea), derived from the forest use by the indigenous community of Nuevo San Juan Parangaricutiro from Michoacan State, Mexico, were used. The chemical composition in wood and bark was determined and the tannin content was evaluated by two methods of extraction: aqueous extraction and ethanolic extraction. In general, the results obtained varied as follows: pH (4.25-5.19), ash (0.08-10.23%), total extractives (6.9-49.5%), solubility to soda (25.36-70.9%), Runkel lignin (17.64-47.33 %), holocellulose (32.74-86.51%), alpha-cellulose (30.58-61.20%), tannins (0.26-10.67% by aqueous extraction, 0.23-12.21% by ethanolic extraction). No heavy metals were detected in the ash. The bark of Quercus candicans and Q. laurina, could be used for the extraction of tannins.
In the xylem of growing trees water fills both free spaces in the cell walls and capillary spaces. For this reason its share in the tree mass is very high. As a result transport of logs obtained from fresh-felled trees is mainly equivalent to the transport of contained water. The primary aim of this study was to determine wood moisture content in growing trees in the selected season of the year. Absolute moisture content of tested wood was established at 62.4%. Average moisture content in heartwood was 60.6% and it was lower by approx. 6% from moisture content in sapwood. Moisture content of the oak heartwood is high, similar to central part of the trunk of non – heartwood species. It is an exceptional situation in comparison to heartwood species, particularly conifers.
This study investigated the mechanically treated sugarcane bagasse cellulose / natural rubber composites. The novelty of this work is based on sugarcane bagasse treated by supermass colloider and an acidification. Properties such as morphology, solvent uptake, diffusion coefficient, transport mechanism, and thermal stability of vulcanised natural rubber (RB) and its composites were investigated. The acid and mechanical treatment showed less aggregates in the composites than bagasse cellulose composite. The transportation mechanism of solvent diffusion suggested that irregular particles are responsible for solvent absorptions. The composites generally showed reduction in swelling rate which was attributed to tortuosity of the path and reduced transport area in the composites compared to neat natural rubber. There was a decrease in the thermal properties of natural rubber with the addition of the reinforcing fillers.
This study examined the creep performance of self-tapping screw connection in wood members and wood-plastic composite (WPC) members that had been subjected to changes in moisture and stress levels. It was found that the self-tapping screw’s joint strength depended on interlocking and friction force between wood and screw threads, between WPC and screw threads. The pine (Pinus spp.) and the WPC had almost the same creep properties. In wet condition, the pine’s creep was higher than the WPC’s. Burgers mode was able to precisely simulate the short-term creep performance of screw connection in the pine members and in the WPC members. In the wet condition, the creep was apparently higher than that in dry condition. Temperature and relative humidity were two important factors that influenced creep. The higher stress level was, the larger amount of creep would be. Creep rate was the largest in both wet condition and high stress level. It is recommended that the maximum tensile stress level should be limited to 40 % for screw connection in the wood members and the WPC members.
The purpose of this study was to develop durable natural colorant modified with liquid glass (SiO2) to be used on wooden materials and determine their desorption performance using the leaching method. For this purpose, the natural colorant was extracted from the smoke tree (Cotinus coggygria) performing boiling method. Then, mordants; oak ash (3% by weight), and vinegar (10% by weight) (CH3COOH) were added to mixture. As the last, liquid glass (20% by weight) were added to mixture. The obtained mixture was applied to the Scots pine (Pinus sylvestris L.) and beech (Fagus orientalis) wood samples by using classic dipping and vacuum method. Leaching test was performed at pH3-22°C, at pH7-10°C, 22°C, 40°C and at pH 11-22°C. The results showed that the liquid glass did not protect wood materials in leaching as planned. The effective results can be obtained by changing the application method and amount of the liquid glass. The nature-based colorants can be an eco-friendly alternative to synthetics.
This paper aims at investigating the influence of constitution and sound insulation materials on the sound insulation of wood-frame walls. The effects of stud sizes, stud spacing, layers of sheathing and sound insulation materials on the sound insulation were analyzed and discussed. The results showed that the sound insulation property was influenced by layers of sheathing, stud sizes and spacing, density and thickness of sound insulation materials. The regression model was established with six sets of data and five sets of data were used to verify it. The recommended design scheme of wood-frame wall was determined according to the frequency of daily noise.
The oil and grease resistance of paper after surface sizing with aqueous dispersions composed of film forming polymers, their mixtures with fluorinated polymer or fluorinated polymer and silver nanoparticles was compared. The oil and grease resistance of paper was regulated by changing the composition and intake of aqueous dispersions and paper grade, and it was evaluated by the content of fine surface pores, contact angle, oil absorptiveness, grease resistance, oil repellency on the inclined surface and oil penetration time. The aqueous dispersions were applied on one side and on both sides of paper surface in the size press. The film forming polymer has created a physical barrier against oil and grease, while combination with the fluorinated polymer developed a physical and chemical barrier. The papers sized with aqueous dispersions containing a mixture of film forming and fluorinated polymer with the addition of silver nanoparticles, achieved high oil and grease resistance even with lower consumption of the fluorinated polymer, and also achieved an antimicrobial surface. The more porous paper has achieved the required oil and grease resistance at higher polymers intake.
Nowadays there are no reasoned scientific data on inter relation of resonant properties of spruce-tree wood and its chemical composition. Thus the purpose of the study was to reveal the features of sonorous spruce in view of the content of basic organic substances in their timber. 20 model trees at the age of 180-190 years were selected as material for studies in taiga woods in the north of Kirov region of Russia. Special 0.5 m long blocks were made from each model tree at height of 1.3 m. Standard 20×20×300 mm samples were made from those blocks. Test samples were kept at room dry conditions for 2 years. After that dendro acoustic studies were carried out on them to define acoustic constant in different directions with respect to timber fibers. Further the percentage of cellulose, lignin, extractives and ashes in them was defined applying standard techniques. As a whole the chemical composition of spruce tree resonant wood lies approximately within the same limits as in common wood of the breed given. However significant influence of cellulose on a longitudinal acoustic constant and lignin on a radial constant is revealed. Joint influence of lignin and cellulose on a tangential constant is…
This study investigated the effects of board thicknesses and temperature on formaldehyde emission (FE) for different wood based boards, sampled from standard particleboard (PB) and medium density fiberboard (MDF). Test samples with the thicknesses of 8, 12, and 18 mm analyzed for formaldehyde emission at temperatures of 10, 20, 25, and 30°C and 65% relative moisture conent for 60, 120, and 180 minutes after production. The highest value of FE was found at 1.2922 ppm for PB and 0.3800 ppm for MDF of 18 mm, treated at the temperature of 30°C. The lowest emission was found to be 0.0611 ppm in the PB of 8 mm, and 0.0444 ppm for 18 mm MDF, treated at a temperature of 10°C. A significant increase for FE was detected in all board types at the temperatures of 20, 25, and 30°C. However, a significant decrease was also detected at 10°C for all types of boards. Accordingly, an increase from 101% to 1,192% and a decrease from 39% to 9% was observed for PBs. MDF samples yielded better results as an increase from 4% to 280% and a decrease from 55% to 31%. Regarding distance to E1 (0.10 ppm), all values were above the…
The thermal treatment of wood leads to chemical, structural and natural changes in the wood components which can significantly affect the adhesive bond performance of the wood in various ways depending on the type of adhesive that is used. In the present research, fir wood (Abies borrissiregis) was undergone thermal treatment at 180°C, and 200°C for 3, 5 and 7 hours. Two different types of adhesives were used for the adhesive bond: polyurethane (PUR) and polyvinyl acetate PVAc. During all the wood treatment conditions, higher endurance in the bonding shear strength was noticed for the non-modified samples and the shearing strength by compression load was decreased while the thermal treatment was becoming more intense. Generally, while the PVAc bond shows better performance during the adhesion and higher modulus of rupture in comparison with the polyurethane PU after the thermal treatment of the wood.
Filaments from a mixture of wood powder and polylactic acid (PLA) polymer were made and used for 3D printing. Different wood ratios were used: 10 %, 20 %, 30 %, 40 %, and 50 %. Specimens were 3D-printed with fused deposition modelling (FDM) printer and conditioned in climates with different levels of relative moisture (RH): 33 %, 65 %, and 87 %. Moisture content (MC), dimensional swelling, and bending properties of printed specimens were measured after conditioning. The results showed that specimens made from filaments with higher wood content had higher moisture content, larger dimensional swelling, and lower modulus of elasticity (MOE).
WOOD RESEARCH Volume 63, Number 6
This study analyses beech wood surface discolouration induced through UV radiation during an accelerated ageing process and with radiation emitted from a CO2 laser beam operating under specific settings. The results show that the extent of beech wood surface discolouration was dependent on the amount and the type of the energy delivered and on the absorption performance of the main wood components. It was observed that increasing irradiation dose caused decreasing wood surface lightness in both UV radiation and CO2 laser-produced radiation scenarios. In most cases, the values of colour coordinates a* and b* increased, and the wood surface was gradually turning dark brown. At high irradiation doses from the CO2 laser, there were recorded decreasing trends in a* and b*, and the beech surface darkened substantially (up to black). To attain purpose-oriented wood surface discolouration under specific modification modes, there is necessary to carry out thorough chemical analyses of the treated wood surface and to express quantitatively the dependence between the energy supplied, colour, adsorption capacity of the main wood components and the ongoing chemical changes.
Spruce samples (Picea abies Karst.) were irradiated by strong ultraviolet (UV) light emitter mercury lamp and another series of specimens were treated with the combination of UV radiation and water leaching. The total duration of UV radiation for both series of specimens was 50 days. The colour parameters (CIE L*, a*, b*) were measured and evaluated after both UV radiation and water leaching. The increase of redness value was two times greater than the yellowness increase based on the initial value at the end of 50 days treatment. The leaching partly removed the yellow and red chromophore molecules generated by the UV radiation. The samples become slightly lighter after water leaching. The leached samples increased slightly more in yellowness and redness during the first 4-6 days of UV radiation than those of the dry series. The change of surface roughness of the specimens was monitored by diffuse reflectance infrared spectroscopy, because the change of roughness alters the light scattering properties of the surface. The roughness of the samples increased during the UV irradiation, and the tendency of roughness change mirrored that of yellowness change. The leaching reduced the roughness value in all examined cases. Good correlation was found between the…
The energy properties and physicochemical structure of torrefied Quercus variabilis cork were investigated with torrefaction between 150°C and 300°C in a tubular furnace. The mass yield, energy yield, and physicochemical properties of torrefied cork were characterized via proximate analysis, elemental analysis, colour analysis, and scanning electron microscope. The results showed that volatiles, moisture content, and the ratios of oxygen to carbon and hydrogen to carbon decreased with increasing torrefaction temperature. Ash content and fixed carbon content increased with increasing temperature, and the enhanced fixed carbon content resulted in the increase of high heating value (HHV) of cork. The HHV compared to untreated cork increased by around 16% after torrefaction at 300°C for 1h. With increasing torrefaction temperature, the cell cavity increased in size, the corrugation was less deformed, and less sediment appeared on cell walls. In conclusion, torrefaction improved both the energy and physicochemical properties of cork. In addition, FTIR and CP/MAS 13C NMR spectra analysis showed that polysaccharide degraded at 200°C, and lignin degraded between 250 and 300°C. Although suberin had better thermal resistance, its NMR signal intensity decreased after torrefaction at 300°C.
Our research about wood physical properties of Quercus robur L., Q. petraea (Matts) Liebl., and Q. pyrenaica Willd., for cooperage was founded on the calculate of wood grain to estimate the change of this property in the Galician oaks. Overall, 45 trees were selected in 15 oak forests of the provinces of Lugo and Ourense (Galicia, NW Spain), of which we obtained 45 thin slices of wood at 60 cm tall on the trunk, and 194 wood samples parallelepipeds of 2 × 2 × 4 cm ± 1mm. The grain of Quercus pyrenaica and Q. robur are similar to oaks Limousin region, France. Quercus petraea is comparable to the Vosges oaks. Now, both regions are among the most important sources in quality oaks for manufacturing barrels. Our global objective was to realize a detailed description on the physical properties of wood of these species for its possible use in industry cooperage. For this, the aim of this second work was to continue with the study of wood grain.
The hydraulic conductance as estimated by Hagen Poiseuille equation was tested on five Nigerian timber species: Brachystegia nigerica, Afzelia africana, Periscopsis elata, Erythrophleum suaveolens, and Daniella oliveri using spent-engine oil (SAE 40), diesel, kerosene and solignum. The wood of Brachystegia nigerica and Afzelia africana gave more conductance (penetrability) to kerosene, diesel, solignum and spent-engine oil than the other three. The wood of Brachystegia nigerica and Afzelia africana gave the highest vessel lumen radius of 0.18±0.06 mm and 0.12±0.01 mm respectively, while Daniella oliveri, Erythrophleum suaveolens and Pericopsis elata gave the lowest vessel lumen radius 0.09 ± 0.01 mm, 0.07±0.01 mm and 0.05±0.002 mm respectively. The less viscous oils: kerosene, solignum and diesel with viscosities 0.015, 0.019, and 0.043 centipoises respectively at 28°C showed more penetrability than the more viscous spent-engine oil of 2.92 centipoises. There is a positive correlation between the vessel lumen radius and hydraulic conductivities of the four treatment fluids (P ≥ 0.05).
This paper presents a concept for a seismic evaluation method for wood frame construction based on analyzing the nail connection performance status. An empirical nail model adjusted using an energy equivalence principle is proposed and experimentally validated. Then, a pushover analysis is conducted on a finite element model of a wood frame construction with a practical configuration, and the structural performances under different seismic hazard levels are evaluated based on the indicators given by FEMA 273. With the methodology proposed in this paper, engineers are able to directly perform an effective seismic evaluation by analyzing the nail connection performance status, from which the main nonlinearity of the wood frame construction originates.
This contribution deals with the resistance of various materials and coatings used in wood constructions to mould growth and in the case of wood and varnishes also to bacterial growth. For testing the resistance to mould growth, the standard EN 14119, method A2 (without agar medium) and method B1 (with agar medium) were used. Tests were performed with Aspergillus niger, Chaetomium globosum, Penicillium funiculosum, Gliocladium virens and Paecilomyces variotii. Resistance to bacterial growth was tested according to the standard JIS Z 2801 with bacteria Staphylococcus aureus and Escherichia coli. Most of materials tested without agar medium were resistant to mould growth. However, the addition of the agar medium (simulation of real conditions; high dampness and presence of nourishment) predictably caused worse results. Cement bonded particleboard, extruded polystyrene and water-borne varnish were very resistant to moulds. Moreover, the water-borne varnish showed a heavy resistance to microbial growth, while a two solvent-borne polyurethane varnish showed no resistance to microorganisms.
Two types of pine wood were used to produce activated carbon (AC) by chemical activation with phosphoric acid. The yield of the activated carbon (CAs) obtained by considering the following factors in the process: species, activation temperature and impregnation ratio (R = wood mass/dissolution mass), the variables of such factors being the species Pinus pseudostrobus (Pp) and Pinus leiophylla (Pl), temperature values 400 and 500°C, and values of R (1:1, 1:2, 1:3), respectively, thus having 12 combinations. The results indicate that the best performance was in the treatment with Pp 400°C and with R = 1:1. A surface area of 790 and 801 m2.g-1 and a total pore volume of 0.312 and 0.316 cm3.g-1 were obtained for the Pp 500-2 and Pl 500-2 carbons, respectively. Likewise, the adsorption capacity of ammonia and gasoline vapors of the carbon obtained was determined.
This paper present the results of application of inorganic minerals and organic polymers for elimination of sticky impurities "macrostickies" in the processing of recovered paper. The impact of individual agents has been monitored on different species of suspensions. On the dark suspension of recycled fibres VL5 with a brightness 53% ISO and an ash content of 17.6%, and the suspension VL1 with a brightness 64% ISO and an ash content of 29.4%. From inorganic minerals, the highest efficiency was achieved in the elimination of macrostickies using bentonite Hydrocol OT. At a dose of 5 kg bentonite.t-1 b.d. recycled fibres efficiency of 65.1% for suspension VL5 and 58.7% for VL1 was achieved. The highest performance of the Acefloc 2550 was achieved from the polymers. When applied to the VL5 suspension, the macrostickies were reduced by 57.1%, and when applied to the VL1 suspension, the macrostickies content dropped by 56.5%.
For the shortage of timber resources and the sake of the formaldehyde emissions, people desire to use non-adhesive bonding technology. This paper studies the chemical composites of black liquor, at different contents ranging from 20 to 40 wt%, into fiberboards made from wheat straw pulp. Adding a little black liquor has positive effect on qualities of boards, contributing to presence of proteins and lignin in black liquor, but adding too much liquor would decrease properties of them for the ash content. The FT-IR measurements indicated that there are more low-molecular substance and hydrogen bonds producing after fining and thermopressing processes. The thermo analysis were conducted to better understand these results. The physical and mechanical properties of the resulting fiberboard were evaluated. The results showed that binderless fiberboards by adding 30 wt% have good mechanical and water resistance properties which can partly satisfy the requirements of the relevant standards specifications.
As the industrialisation and technological developments increase; the search for functional material which is environment-friendly, non-toxic, flame resistant, with a broad applicability and with high-temperature endurance also increases. Even though the wood material corresponds most of these features, its possession of an organic structure causes it to be affected negatively by damages occurring under proper conditions in the outdoor environment. Due to this reason, this study is conducted to prevent damages (biotic, abiotic pests, fire, etc.) caused by the environment to the wooden material, and to determine some physical and mechanical properties of wooden material impregnated with quechua, borax and boric acid, which are used to extend the usage life. Those features are needed in an outdoor environment. The Scotch pine (Pinus sylvestris L.) test specimens are prepared with borax, boric acid, borax+boric acid, from borax compounds, which have a great potential in Turkey, and with quechua, one of the natural impregnation substances. Then these samples are impregnated with three different (1%, 3%, 5%) solution concentrations according to ASTM 1413-76 standards and some physical-mechanical property changes are investigated. After impregnation, samples are tested and compared with control samples. According to the test results; the lowest oven dried density change is…
The article focuses on processing of Reynoutria japonica an invasive alien species that is generally extirpated with major costs for its negative impact on biodiversity. It is the biodegradable waste that could be effectively used in energy industry. By examining first energy data (ash content, low melting temperature, nitrogen content etc.) it was found that Reynoutria japonica is not possible to be used separately for energy purposes. Therefore, the alternative of pelletizing six mixtures containing Reynoutria japonica and spruce sawdust in various content ratio was examined with the aim to produce alternative fuel pellets for automated boilers. The pelletization conditions were determined and the pellets quality was evaluated (durability, density etc.). Ash melting temperature was also evaluated. It was found none of the prepared mixtures needed an additional binder for a pelletizing process. It was assessed that the Reynoutria japonica input sample did not need to be dried after collection, since its moisture was sufficient for the pelletization. All samples met the parameters of the calorific value, which is greater than 10 MJ.
Elastic constants of particleboard layers were investigated using by means of ultrasonic waves and compression tests under different humidity regimes. Three Young’s modulus, three shear modulus and six Poisson ratios were determined. Three longitudinal and six shear wave velocities propagating along the principal axes of anisotropy, and additionally, three quasi-shear wave velocities at 45° angle with respect to the main axes of anisotropy were measured. Compression tests were also conducted in order to measure the accuracy of ultrasonic method. Comparing with calculated values, the predicted Young’s modulus values in the principle directions are acceptable. The shear values calculated using ultrasonic method are higher than those determined from compression tests, particularly in the perpendicular directions. Some of the Poisson’s ratios predicted by ultrasound seem to be extreme. The influence of moisture content on Poisson’s ratios is variable. It can be concluded that ultrasonic method can be used as alternative in determination of elastic modulus for particleboard layers at different moisture conditions. The accuracy of ultrasound for determining the Poisson’s ratios of particleboard layers is questionable.
Effects of screw diameter, pilot hole diameter, and material’s anisotropy on the withdrawal resistance of bamboo oriented strand board (BOSB) has been evaluated and the results has been compared with conventional particleboard (CPB). Results indicate that the effects of screw diameter on the face withdrawal resistance in BOSB have significant differences, whereas the edge withdrawal resistance was not. In contrast, the effect of screw diameter on face and edge withdrawal resistance in CPB has been statistically significant difference. The effect of pilot hole diameter on the face and edge withdrawal resistance both in BOSB and CPB has significant difference, the withdrawal resistance decreased as related to increasing pilot hole diameter. Furthermore, the withdrawal resistance in BOSB is anisotropic, whereas the relative superiority is sorted by the face, edge and end in turn. In addition, the withdrawal resistance in BOSB was much higher than CPB in all directions.
As a new kind of pulp that can protect the environment by conserving wood resources, ultrasonic wheat straw pulp has received increasing attention. It is prepared by the mechanical effect of ultrasound, the effect of cavitation, and thermal effect, and it does not require a large amount of chemical additives. Different pulp methods yield differences in performance. The conventional method of sizing is difficult to achieve the ideal of wheat straw pulp ultrasonic sizing effect. This work examined the effects of additives and surface charge on sizing by studying ultrasonic wheat straw pulp with 0.25% alkyl ketene dimer (AKD) added in the form of a commercial emulsion without separate retention aids. As a retention aid cationic polyacrylamide (CPAM) contents were prepared and added to fiber suspensions at the wet end of the papermaking process. The relationship between CPAM and the zeta potential of papermaking furnish and sizing degree, the strength properties of the paper sheet, and the factors that affected measuring the zeta potential were investigated. As the CPAM content increased, the surface morphology, the zeta potential and the strength properties of the paper sheet presents a curve.
In the presented paper composite actions of various mass timber panels with concrete layer are compared. The composite action of timber and concrete by grooves in wood and by adhesive was realized. In the frame of experimental investigation bending test of real scale composite panels with cross-laminated and nailed/glued vertical planks mass timber was performed. In the analysis, vertical mid-span deflection of tested panels was compared and also some technological aspects of their production were taken into account.
Volume 62 (2017)
WOOD RESEARCH Volume 62, Number 1
Salix psammophila can grow rapidly in desert and grassland areas. As an abundant bioresource, it is useful to understand its cell morphology, chemical compositions and mechanical properties. In this study, Anatomical properties of Salix psammophila in different annual rings were measured and compared. Fourier transform infrared spectroscopy and chemical titration were used to estimate cell wall chemical compositions. Moreover, mechanical properties in different annual rings were measured through nanoindentation. Fiber cell lumen diameter, fiber cell wall thickness, vessel cell lumen diameter and vessel cell wall thickness of Salix psammophila were measured to be 7.371, 2.285, 32.541 and 1.926 μm, respectively. Fiber cell lumen diameter, fiber cell wall thickness, vessel cell lumen diameter differs among the annual rings. The cellulose, hemicellulose and lignin contents of Salix psammophila were 44.43, 34.99 and 17.93 %, respectively. Both hemicellulose and lignin contents varied among the annual rings with more hemicellulose but less lignin at the annual ring closer to the pith. The modulus of elasticity (MOE) of fiber cell wall of Salix psammophila decreases from pith to bark.
The botanical family Fabaceae is the most representative in terms of diversity in Brazil, and it contains species of great importance to the domestic and international timber trade. In spite of numerous attempts to combat illegal logging, this practice is still common in Brazil, making it necessary to seek more accurate techniques for identifying wood species. This study aimed to test different protocols for extracting DNA from dried heartwood of Amburana cearensis (Fr. Allem) A. C. Smith (Cerejeira), Dypterix odorata and Peltogyne confertiflora. Additionally, these species were characterised through visual inspection and scanning electron microscopy. Five DNA extraction protocols were evaluated with six replicates. DNA amplification was conducted for the rbcL gene, a molecular marker of conserved regions in plants. It was possible to extract and amplify DNA from the dried heartwood of the tested species, with Protocol 2 (QIAGEN kit) being the most efficient.
Ureaformaldehyde adhesive requires hardener and about 4-6.5 pH to be cured. In this study, boric acid, boron oxide, borax, sodium perborate tetrahydrate, sodium chloride, sodium chlorite and control samples containing ammonium chloride was used as an hardener to investigate cureability of urea formaldehyde adhesive. Chemicals used as an hardener tested to demonstrate the effect on gelation time, swelling properties, MOR and MOE. Ammonium chloride, boric acid and boron oxide improved to properties when used as an hardener in single use or in mixture.
The paper deals about an anti-mould efficiency of nano-zinc oxide applied into wood alone (0.1%, 0.33%, 1% and 3% ZnO) or in combination with polyacrylate (5% Paraloid B-72) and essential oils (1% and 3% clove, oregano or thyme oil). Treatment of lime tree and maple samples 50×10×5 mm (L×R×T) with these chemicals was performed by one-step or two-step dipping at 20 °C/1 h. The anti-mould efficiency of used chemicals was determined by the standard STN 49 0604 – evaluating effect of chemicals against growth of four moulds (mixture of Alternaria alternata, Aspergillus niger, Penicillium brevicompactum and Chaetomium globosum) in the 7th 14th, 21st and 28th day. The anti-mould efficiency of ZnO nanoparticles was relatively poor, however, it was evidently improved in presence of clove and oregano oils, mainly in the first 7 days of the mould test.
The article describes a method of preparing particles from waste particle boards (chipboards) and oriented strand boards (OSBs). Their reuse is the main target of recycling. Method of their destruction was determined in this work. Agglomerated materials disintegrated after an initial destruction were further processed under specified conditions with regard to the material humidity, type of materials, contained adhesives and given characteristics of final particles - wood chips. Wood particles obtained were characterized by a fractional composition and amount of residual formaldehyde as an important parameter for the reuse of waste materials in production of furniture boards. New chipboards and pulp for production of middle density fiberboards (MDFs) will be provided from such defined particles.
To endow wood materials with a thermochromic function, an organic thermochromic agent consisting of thermochromic dye, bisphenol A (BPA) and long-chain alcohols (1-tetradecanol (TD), or 1-hexadecanol (HD)) was used as a dye to prepare reversible thermochromic wood (RTCW). The colorimetric properties, including total color difference (ΔE*ab), lightness index (L*), red-green index (a*), and yellow-blue index (b*), were investigated at different temperatures. The color change temperature range and color hysteresis of RTCW were also analyzed. The color difference unit of National Bureau of Standards (NBS) was used to determine the color change temperature range and the achromic (chromic) temperature. In the decolorization process, with the temperature increasing, the values of ΔE*ab, L* and b* of the RTCW samples increased, and the values of a* decreased, but the values of ΔE*ab, L*, a*, and b* were just opposite in the colorization process. Meanwhile, the color of the RTCW with TD or HD could repeatedly change between red and light brown (wood colore) within a color temperature range of 25-35°C or 37-49°C respectively, presenting a “color hysteresis” phenomenon over a heating (decolorization) and cooling (colorization) cycle. The achromic and chromic temperature of the RTCW samples with TD was 31°C and 25°C respectively while…
The present study investigates anatomical structure of secondary thickening parts (rootstem- branch) of endemic monocot Dracaena cinnabari. The measurement of microscopic structure parameters was carried out using analytical imaging. The differences between vascular bundles were determined. The results show presence of concentric vascular bundles in all investigated plant organs. In general, the parenchyma cells cover majority of the total area (an average of 77%), much less covers xylem (an average of 19%) and phloem (an average of 4%). The results indicate that the plant body is well adapted to sub-tropical climate regimes and specific environmental conditions prevailing on the island such as limited access to soil moisture and sufficient nocturnal dew which is essential for plant growth and survival.
The aim of the research was to evaluate the potential of wood anatomy parameters as stress indicators on base of changing cell characteristics and proportion of latewood in Picea abies stands damaged by extreme climatic conditions in combination with high air pollution load during the winter 1995/96. The research was carried out in the Ore Mountains (Czech Republic), where sites were located along the gradient of forest damage. Preliminary analyses showed the decrease of lumen width, cell wall thickness and the number of tracheid in the tree rings of spruce at heavily damaged site. Significant difference was shown between sites with different damage level. Moreover the difference in reaction dynamics of earlywood and latewood parameters was recorded. The length of stands regeneration was shown to be around 3 years depending on the assessed parameter and the damage rate.
It was aimed to investigate thermogravimetric analysis (TGA), differential-thermogravimetric (DTG), and differential-thermal analysis (DTA) of Oriental beech (Fagus orientalis L.) wood treated with some leaching resistant borates such as sodium tetraphenylborate (STPB) and phenylboronic acid (PBA). In this study; 0.25, 1.00, and 4.70 % aqueous solutions of borates were prepared. Results of the study indicated that pyrolysis occurred in three stages for STPB and PBA treated Oriental beech wood. Generally, while concentrations of the STPB and PBA increased, Ti and Tmax values of STPB and PBA treated wood specimens decreased. Residual char contents of STPB and PBA treated wood specimens for all concentrations were higher than untreated control specimen.
In this work, the effect of decorative veneer type, wood structure and wood shape on the dimensional stability was studied in a laboratory with a simulated heating system. Poplar/seven layer plywood engineered hardwood (structure C) or a 9 mm thick poplar substrate layer wood which contained the two veneer surface layers, structure A and structure B were used. The results indicated that whatever the structure and decorative veneer of flooring were, the dimensional stability of engineered wood flooring had a better performance in length; In width, with the same structure and decorative veneer, the dimension stability of engineered wood flooring with the veneer shape of mono-block was better than the shape of three splice; With the same decorative veneer, the dimensional stability of structure C was best, the second was structure B, and structure A was the worst; With the same structure, the dimensional stability of engineered wood flooring decorated with birch was best, the second was eastern black walnut, the third was eucalyptus, and maple was the worst. Thus, the engineered wood flooring of structure C decorated with birch with mono-block veneer was judged to be better for the dimensional stability.
The aim of the paper was to compare the results of different methods of measuring the tree rings curve performed using different images of a reference sample made from a historical wooden con-struction of silver fir wood. The tree-ring curves were measured using two measurement methods: firstly manually on the traversing table using a stereo microscope with TSAPWin dendrochronolog-ical software and secondly in the LignoVision software (LV) from uploaded image files (scans, modified monographic scans and X-ray scans). Automatic image analysis was also tested in this software. Results showed that the tree-ring curves based on manual determination of printed-out photographs and scans using a stereo microscope on a traversing table and on manual determination of identical digital images in LignoVision matched to a large extent the data obtained by measuring the physical sample. The results were worse when tree-ring curves were measured from an X-ray scan, both using stereo microscope on a printed image, and using LignoVision. The automatic anal-ysis of the LignoVision software showed a high error rate. Finally, the results of measurements of individual image types and the possibilities of practical use of individual image records of dendro-chronological samples are discussed.
The effect of cutting parameters and tool parameters on cutting forces and tool wear were investigated in high density fiberboard (HDF) peripheral up-milling using toughened ceramic cutting tools. The results showed that whether at low speed cutting or high speed cutting, the tangential forces Ft and normal forces Fr increased slowly with the increase of cutting length. The tangential forces Ft and normal forces Fr at low speed cutting were higher than that at high speed cutting. The tangential forces Ft and normal forces Fr decreased with the decrease of wedge angle in the same rake angle. Then, the effect of high cutting speed on the flank wear was greater than that at low cutting speed. The bigger wedge angle tools led to the serious flank wear. The main wear pattern in milling HDF consisted of pull-out of the grain, flaking, chipping and cracking, the main wear mechanism were adhesive and abrasive wear.
The objective of the present study is to determine the behaviour of two typical types of fastener (nails and screws) used in trusses made of Gmelina arborea and Hieronyma alchorneoides timber. Wood joints with metal fasteners (nails and screws) and five angles (0°, 30°, 45°, 60° and 90°) were subjected to tension and compression loads in order to establish values of displacement in relation to applied loads, strength, stiffness values, mode of failure and a model for prediction of stiffness for intermediate orientations. Results indicate that the differences in loads and displacements appear among species in the compression test, whereas those differences appear among fasteners in the tension test. The results obtained for stiffness indicate that jointsofH. alchorneoides wood present the highest values. Models for prediction of stiffness for truss joints of intermediate orientations were: in compression, while for tension the model was.
The work deals with the monitoring of selected parameters in the model of terrestrial forest fire, which originated in forest litter (natural challenged material). A needle of black pine (Pinus nigra) was used as a fuel. For the model there was developed forest fire apparatus - wind tunnel, which simulates terrestrial forest fire on the basic model Superior Técnico in Lisbon (Portugal). In the apparatus, there is possibility to placing a sample on the basis of changes of coniferous litter and regulate the speed of the airflow over the layer of litter. The work reviews the effects of air velocity depending on time and temperature of coniferous leaf litter on the wind tunnel and the speed of flame propagation along the coniferous litter layer. In the article, there are original work results which show a significant effect of air flow over the surface of coniferous litter on a fire and the flame propagation speed after layer of litter. Threshold limits of the flow rate of air are in the range , in which there is an increase in linear speed of the spread of fire of 2 to 2.5 times. Subsequently, the linear speed of spread for models of terrestrial…
This paper is an attempt to evaluate the lignin formation in tracheid walls within the stem circumferential area in mature Scots pine (Pinus sylvestris L.), and establish the correlation between lignin content, and diameter at breast height and hydraulic conductivity in mature pine. The independent variables included lignin content (Lc) in tracheid walls within the stem circumferential area, and pine diameter at breast height (DBH), and the dependent variable was the relative conducting surface of stems (Sa/Nmass, Eas/Nmass). Research material came from the 89-91 year old pine stand in the north of Poland. Chemical analysis included mature wood area, i.e. last ten annual rings at 1.30 m (DBH). The results show clear interdependence between the relative conductive surface (stem hydraulic conductivity), and tree diameter at breast height and lignin content in tracheid walls within the stem circumferential area. Biometric features of pines grown in fresh coniferous forest (FC) and in fresh mixed coniferous forest (FMC) conditions were functionally linked. The link between these values was clear, although it varied, and could be approximated using the linear function.
WOOD RESEARCH Volume 62, Number 2
The reason for the excellent natural durability of Sweet chestnut wood can be primarily explained with the extractives incrusted in the wood cell wall. These compounds basically involve tannins, which protect the heartwood against wood decaying microorganisms. Research carried out on the wood of ring-porous broadleaved species revealed that there is a significant radial variation in the concentration of phenolic extractives. The present research focused on the radial distribution of total phenol and ellagitannin content in the heartwood of Sweet chestnut stems, originating from different forest stands. It was also investigated if there was a significant correlation between water supply of the treesand the distribution of phenolic compounds. Total phenol and ellagitannin contents generally increased from juvenile wood towards the sapwood/heartwood boundary, lowest values were determined in sapwood tissues. Respecting water supply it was established that the heartwood of trees growing in a dryer foreststand, contained significantly higher phenolic extractives compared to trees in well water-supplied, fresh forest sites. However, ellagitannin contents didn’t significantly differ between sites. The utilization of the wood of naturally durable European species, including Sweet chestnut, will gain in importance in the future basing on the growing common ecological awareness of the population.
The present study describes the possibility to polymerize functional composite modifier within wood cell walls to obtain functional wood composites (FWCs) with poplar wood acting as the base template. The physical and mechanical properties of the composites, including density, bending strength, compressive strength parallel to grain, surface hardness and water uptake, were evaluated. The FWCs were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD). According to the results, the functional composite modifiers were successfully in situ deposited into the wood structure by kiln drying. The chemical treatment not only significantly improved the physical and mechanical properties of wood, but also provided the wood with better hydrophobic properties. The abbreviations for substances used in this study are: N-wood (natural wood), MD-wood (methylolurea/DMDHEU copolymerization treated wood), FCM-wood (functional composite modifier treated wood).
The variability of black locust wood hardiness along the stem determines potential uses for this type of material. Characterization of this parameter was conducted based on samples taken from black locust stands in the western of Poland. Study material drawn from each sample tree was divided into three groups (lower stem part, center of the stem and base of live crown) and measuring was performed in three directions (radial, longitudinal and tangential). Due to bimodal distribution of the data, longitudinal direction was analyzed separately from radial and tangential directions. For the longitudinal direction, significance of differences between various stem parts was confirmed (p
The disposable chopsticks caused a large amount resources waste of bamboo and wood. Thus, it has a significant resources and environmental benefits using wormwood stem as raw materials to make disposable chopsticks. In this paper, the radial compression and bending performances of wormwood stem were tested with different moisture content, which provide a reference for reasonably design the grinding device of wormwood stem and the feasibility of wormwood stem instead of bamboo chopsticks. The test results show that: the mechanical properties decrease with the increase of moisture content. In the actual grinding process, the moisture content of wormwood stem is controlled about 20%, it can withstand the radial force of 600N and the bending force of 41N, which meet the load requirements of the grinding processing and use. This study provides a theoretical basis for reasonably design grinding device of wormwood stem, producing and storing high quality herbal chopsticks.
This study deals with non-destructive measurement of wood, i.e. physico-acoustic characteristics (density, dynamic modulus of elasticity, acoustical constant, speed of sound propagation in material and logarithmic dumping decrement). We used two species spruce and larch for measurements. We took wood from two main areas: from Slovakian higher latitudes and from Russia - Siberian areas. Spruce is the main species for the boards of musical instruments and we tried to find another species to replace this one. We measured physico-acoustic properties by two devices: The ultra-sonic tester and device "MEARFA" based on searching correct frequency for each sample. The results show that spruce for top instruments has acoustic constant approx. 12 m4∙kg-1∙s-1 and the "best” value for larch was approx. 10 m4∙kg-1∙s-1. If we compare the methods of measurement of the sound velocity through samples the results for ultrasonic testing are much higher than those provided by resonance-dynamic method. The article also describes differences between physico-acoustical characteristics of sap wood and heart wood, and differences between species.
This article deals with the influence of selected factors (wood species, used adhesive type, carbon reinforcement) on tensile-shear strength of glued layered wood. Tensile-shear strength was investigated on samples of European beech (Fagus sylvatica L.) and European spruce (Picea abies L.). The laminated wood was modified with carbon polymer or carbon fabric, and the tensile-shear strength values were compared with non-reinforced wood. Polyurethane and epoxide adhesives were used for the experiment. The highest tensile-shear strength values were found on non-reinforced beech wood glued by epoxide adhesive. As far as the tensile-shear strength concerns, each monitored factor as well as their mutual interactions were proven to be statistically significant.
Flame retardant treatment is a common method of wood preservation. However, the factory usually uses the same approach to all the wood, but lack of targeted so as to cause waste. This study used poplar and Chinese fir as the species investigated. These species were dipped with boron-nitrogen-phosphorus (B-P) fire retardant. The influences on material loading of processing method, concentration of fire retardant, and drying method were investigated. The contents of B and P were tested by inductively coupled plasma optical emission spectrometry (ICP-OES), after distilled water washing and ultrasonic washing. The results showed that the volume loading increased with the concentration of fire retardant. Freeze-drying can noticeably improve the volume loading, and the impact of the drying method was more notable on poplar than on Chinese fir. The fixation effect of the B and P in poplar was lower by ultrasonic washing than that was by distilled water washing. The fixation effect was opposite in the Chinese fir. Vacuum process was more suitable for the poplar (hardwood), and vacuum-pressure process was more suitable for the Chinese fir (soft wood).
The adsorption of 4-chlorophenol (4-CP) from aqueous solution on activated carbons prepared from hornbeam wood was studied. The adsorption kinetic data were analyzed using pseudo-first order and pseudo-second order models. The adsorption kinetics of 4-CP was better represented by the pseudo-second order equation. The equilibrium adsorption data were described by Langmuir and Freundlich isotherms and the results showed that both models fitted well the 4-CP adsorption; nevertheless, a slightly higher R2 values were observed for the Langmuir model. The effects of solution pH and ionic strength on the adsorption were so investigated. The high 4-CP adsorption capacity (2.71–4.37 mmol.g-1) shows that hornbeam wood is a good precursor for the preparation of activated carbons for the adsorptive removal of organic contaminants.
Methods, processes and equipments currently used for heat recovery systems are very diverse in different branches of industry including paper industry. A very important process applied in heat recovery units is condensate removal from the heat recovery units because of optimization of the heat recovery process and extending the working life of heat recovery units. Using of heat recovery units with condensate removal in paper industry fits the innovation trends and means heat energy saving that can be realized by increase of heat recovery efficiency. Heat recovery system with condensate removal should be installed near a drying cover of a paper machine due to reduction of heat loss and pipeline length. Integration of designed spiral heat recovery unit with condensate removal into the existing dryer section of paper machine in a paper mill will lead to decrease of heat consumption and increase heat recovery efficiency up to 91.7 %.
Investigate the wood modifilers effect on the physical properties of fast-growing poplar wood. Wood modifier was applied to impregnation drying operation on fast-growing poplar, and the characteristics of poplar wood before and after modification were observed with X-ray diffractometer (XRD), scanning electron microscope (SEM), energy-dispersive spectrometer and Fourier transform infrared (FTIR) spectrophotometer to analyze the physical properties of the wood. The modification could significantly improve physical properties of the poplar wood. XRD data illustrated that wood modifier could reduce crystallinity of wood from 39.65% to 36.89%. The findings of energy-dispersive spectrometer indicated that nitrogen (N), oxygen (O) and carbon (C) were evenly distributed in the wood. SEM spectrum analyzed the distribution of wood modifier in the wood pores. The FTIR spectra proved that there was cross-linking reaction between the modifier and the internal parts of the wood, and the amount of hydroxyl decreased sharply.
The aim of investigations was to determine whether the tested models for calculating forces in wood cutting, set up under strictly controlled laboratory conditions, can yield sufficiently accurate results for predicting wood behavior in real cutting conditions. Tests were carried out on oak wood (Quercus robur). On the basis of measured values for the required cutting power, cutting forces were calculated and used for comparison by applying the method of coefficient (Kršljak’s model) and Axelsson’s model. The analysis indicated that there is not a result, but there is similarity in the curve shape, i.e. changes in measured values are followed by corresponding changes in calculated values. It can be inferred that analyzed models are not suitable for the cutting forces quantification, but could serve for comparing different cutting modes. More accurate modeling of the cutting process requires, besides physical, wood mechanical properties as well.
An analysis of the cutting process and tool wear during machining from metal materials has been the subject of many studies. On the other hand, the tool life when machining from wood materials has not received much attention. Optimisation of the cutting process consists of the appropriate selection of major processing parameters as the cutting depth, feed rate and cutting speed in order to ensure adequate machining accuracy at minimum cost, and appropriate process efficiency. Here, we present the results of experimental tests of wearing drills with carbide blades during processing of melamine faced chipboard (MFC). To evaluate the surface quality of the chipboard the maximum radius and area of delamination around the chipboard blind hole are adopted. These parameters are determined independently at the hole entry and exit. Statistical analysis of results using multifactor analysis of variance was carried out. The tool life of drills depends on many combinations of cutting parameters and the wear of the drill blade. In the drilling process, the value of the thrust force mainly depended on wear of tool flank and the feed rate. The cutting speed has little effect on the amount of thrust force and cutting torque.
This paper is focused on the torrefaction of lamellar panels made of wooden species of spruce and beech, with a view to noticing the influences of the torrefaction on the physical and mechanical properties. The working method highlights the special character of the lamellar panel torrefaction as compared to other torrefied products. The obtained results emphasize that the mass losses increase with the severity of the thermal-treatment condition, where as the hygroscopicity and mechanical properties of the material simultaneously decrease. The analysis of the obtained results recommends the use of these panels in humid/moist environment.
Rubberwood particleboard were produced using urea formaldehyde (UF) resin admixed with propylamine as formaldehyde scavenger. 1 % propylamine were incorporated into 8 %, 10 %, 12 %, 14 % and 16 % UF resins, respectively. The effectiveness of propylamine addition to reduce formaldehyde emission from particleboard was examined. Physical and mechanical properties were evaluated according to Japanese Industrial Standard (JIS). The results showed that addition of propylamine had reduced 33 to 65 % formaldehyde emission from particleboard made with different dosages of UF resin. However, the properties of the particleboard were adversely influenced by the addition of propylamine. Higher resin dosage (≥14 %) had counterbalanced the loss of strength and dimensional stability but accompanied by increased formaldehyde emission. As a conclusion, UF dosage of 14 % admixed with 1 % propylamine is the most ideal formulation to produce particleboard with low formaldehyde emission while maintaining the desired properties.
The Paulownia tree (or to its well-known name Chinese empress tree; Paulownia tomentosa) is classified among the most variable wood species of the world concerning usability. Its cultivation in Hungary in form of research plantations has just started in the last decade, first of all for the investigation of energetic properties. Due to this the information related to the physicalmechanical properties of the wood was still not determined, from which aspect this study is essential. The investigated wood with an air-dry density of 0.3 g.cm-3 has shown low bending (42 MPa), compressive (22 MPa), shear (7 MPa), tensile (33 MPa) and impact strength (1.6 J.cm-2) values, based on which its wooden material properties can be compared to poplars considering tree species in the region.
WOOD RESEARCH Volume 62, Number 3
In this work, we drew the experimental or the true creep-recovery curves of Entandrophragma cylindricum known as sapelli from the values obtained during many four points flexural tests carried out on several samples of this hardwood. Thereafter, the experimental values have been perturbed by the white Gaussian noise of the gauges and this allowed us to draw the noisy curves of deformations. The creep test lasted ten hours and the recovery forty hours. Our main target in this work was to implement the recursive discrete Kalman filter, in order to predict or to estimate the deformation of this species undergoing a constant stress. From the simulation, since our estimate and our state have the same expected value, then our estimate is not biased. The true deformation and the estimated deformation curves are almost too close to distinguish from one another. Once the Kalman filter applied to our system satisfied these two preceding criteria, we are able to mention that our estimator has a good response therefore, it is an optimal filter.
Studies on the content and distribution of mineral substances including calcium (Ca), potassium (K), magnesium (Mg), manganese (Mn), iron (Fe), sodium (Na), zinc (Zn), aluminum (Al), lead (Pb) and strontium (Sr) were performed. Samples of Scots pine were gained from stems with Ist degradation degree of tree (considered to grow in the area with weak environmental pollution), IInd degradation degree (strong pollution) and IIIrd degradation degree (very strong pollution). Nitrogen industrial plant was acknowledged as the source of pollution. Samples were collected from butt-end, middle- and top sections of the stem in following zones: sapwood, heartwood adjacent sapwood, heartwood and bark. Results indicate that nitrogen industrial plant causes the decrease of mineral substances content in bark from butt-end section of stems with IInd and IIIrd degradation degree in relation to stems with Ist degradation degree. Calcium content is the highest in heartwood and decreases in the direction to stem perimeter, regardless of stem section and environmental pollution degree. Very strong pollution decreases potassium content in wood in comparison to samples collected in areas with strong and weak pollution. Environmental pollution also decreases sodium content in wood, and increases content of manganese, aluminum, lead and strontium.
The manufacture process, specification and mechanical properties of arc bamboo were studied to support the biomaterial “arc-bamboo recombined in original status (A-BROS)” manufactured by bionic technology. The results indicated that the iso-curvature processed with milling technology is the key technology for arc bamboo, and arc bamboo monomer increases utilization rate of bamboo by 30% and the monomer width (≥40 mm) by more than 90%, as well as excellent bending resistance, these confirm relatively greater thickness of monolayer A-BROS material with slighter glue spread and superior mechanical property. The novel recombinant made by arc bamboo with elegant texture and original status could be used as board and timber, and form new structure, furniture and building materials.
Pine (Pinus pinaster Ait.) wood samples were subjected to a combined treatment by densification and heat treatment. Samples were densified before and after heat treatment. The heat treatment was made inside an oven at 190ºC during 2 to 6 h and wood densification was made in a hot press at around 48 bar pressure and temperatures between 160ºC and 200ºC for 30 min. Compression-set, compression-set recovery after three cycles of water soaking followed by oven drying, density, hardness, bending strength and stiffness and durability against subterranean termites were determined after the treatment. Results show that densification increases density, hardness, bending strength, stiffness and durability against termites. Heat treatment applied after the densification is more effective in reducing compression-set recovery than if applied before.
The advent of lean (waste reduction), six sigma (process variation minimisation) and proper raw material selection are the essential challenges to achieve the required quality on the overall industrial processes. Accordingly a laboratory experiment for the dissolving wood pulping process was conducted on nine Eucalyptus genotypes to measure the change in lignin, viscosity and α-cellulose at each of the six pulp processing stages. The changes to these properties were modelled using the Generalised Additive Models (GAM) and Fractional Polynomial (FP) models. These models proved to be equally important in their unique ways and produced complementary results. The results revealed that Emearnsii genotype produced the best results for both α-cellulose and viscosity, while Enitens genotype was selected for the optimal lignin reduction. Egrandis genotype is the only genotype that proved to have adverse effects on the viscosity property.
In this study, wood modification (thermo-processing and impregnation) and outdoor conditions of storage (natural aging) the effects on the mechanical performance of industrial woodwork was investigated. For this purpose, naturally grown in Turkey and the commercial value of high Scots pine (Pinus sylvestris L.) and chestnut (Castanea sativa Mill) wood was used. Experimental examples are specifically woodwork has been applied in actual size. Considering the previously conducted research literature only diagonal L-type samples used, not on the actual size samples of woodwork. In addition, there is no study that the combination of the heat-treatment and impregnation. This reveals the original values of this study. For preparing of samples is used the double tenon-mortise corner joint from constructions method and as glue polyurethane based Desmodur VTKA and Polyvinyl acetate based two-component D4. Diagonal woodwork test samples prepared by Thermo S class (185°C temperature with a thermo-vapor process protections) applying. After application of the heat treatment, the test samples impregnated with a solution of 95 % natural pine cone resin and %5 pine tannin by dip method (2 hours). Then, the untreated samples (control), only heat-treated samples and heat treatment + impregnated samples kept for 1 year with outdoor conditions (aging). At…
In this study, Moment resistance performance of column-beam joints using cylindrical laminated veneer lumber (LVL) column and glulam beam were evaluated. Two types of jointing methods - Type-A, in which the beam is put on the end side of column and Type-B, in which the beam is inserted into column - were applied. As a result of Type A, Moment resistance of the cylindrical-LVL column jointed with drift pins was shown to be 67 % higher than that of the larch log column jointed with drift pins. The larch log column jointed with GFRP Plate reinforced wooden pins was shown to be 14 % higher than that jointed with drift pins. In Type-B joint, the rotational stiffness of two specimens were 139.4 kN•m/rad. (Non-reinforced specimen) and 272.2 kN•m/rad. (reinforced specimen), respectively, and reinforced specimen was 95 % higher than Non-reinforced specimen. Based on this result it was assured that glass fiber reinforcement is able to reinforce the column.
The paper presents the experimental results of a research aimed at the distribution of the temperature on thecircular saw blade body. The temperature was measured at four distances from the centre of the circular saw blade body (60 mm, 70 mm, 80 mm, 90 mm) by means of an infrared thermometer. Three circular saw blades with the diameter of 350 mm and a variable adjustment of the body (without slots and coating, with slots and without the coating, with both slots and coating) were used for the longitudinal sawing of the spruce wood (Picea excelsa) with the thickness of h = 25 mm. Feed speed vf = 12 m•min-1 and cutting revolutions n = 4000 min-1 were constant. The measured temperature was in the range from 22°C to 30°C. The highest measured temperatures were recorded on the circular saw blade with the slots and coating.
Water borne wood preservatives have been widely used for a long time in the protection of wood either in ground contact or above ground. Copper is still major biocide component used today in treatment plant for wood protection despite the environmental concerns over copper-rich preservative systems. On the other hand, water repellents are considered to be potential additives for biocides, resulting in the decreased moisture content, reduced biocide leaching and increased dimensional stabilization. In the present study, copper azole (CA) was used as wood preservatives to the natural weathering for 6, 12 and 24 months respectively. In addition, semitransparent wood stain was used as post treatment with CA, and paraffin and silicon additives were incorporated in to biocide to be water repellent. Paraffin additives reduced the retention values as compared to other formulations. The highest color change and gloss loss were obtained with Scots pine control samples within the six months. CA pretreatment before wood stain was promising by indicating the lowest color change. Color change was reduced by the increasing ratio in paraffin and silicone additives. Combination of CA with wood stain and silicon additive could reduce the copper leaching to some extent.
The variations in number and method of applied joints within storage furniture gave idea for this investigation. Importance of joint selection and its geometrical characteristic is clear if we bear in mind that the joints are critical points in the structure, and the rigidity and durability of storage furniture are in direct correlation with the type of the applied joint. Results presented in scientific papers provide little useful information to the engineer for the safe selection of the optimal joint. Number of joints along the connecting line (depth of the box type element) engineers determined empirically. In order to define stress state in the storage furniture, data on size of the load, that the box element has to with stand during its use, should be determined. The aim of this study was to determine the size and character of the loads in corner joints in storage furniture. Based on this data, as well as on the basis of information about the strength of the corner joints it is possible to calculate the required number of appropriate joining elements for each separate case.
This article deal with investigation of mean arithmetic deviation of the waviness profile (Wa) on edge surface after edge milling of medium-density fiberboard, medium-density fiberboard with single-sided lamination and spruce edge-glued panel. Edge milling afftected feed rate 4, 8, and 11 m.min-1 and cutting speed 20, 30, 40 a 60 m.s-1. There were used for milling 3 types of tungsteen carbide blades with different composition and treatment (HW1, HW2 and HW1 + CrTiN coating). Working results show that the lowest values of waviness were found with a spruce glulam. Considering the machined surface quality the most suitable blade is HW1, then HW1 + CrTiN coating and the worst one is HW2. The lowest measured values of Wa were found with the feed rate of 4 m.min-1 and cutting speed of 60 m.s-1. The increase in cutting speed resulted in the drop in the values of average Wa, while the increase in feed rate had the opposite effect.
Buried wood samples of gold “Phoebe sp.” (Samples #1, #2 and #3) were identified based on their microstructures and on the comparison of their characteristics with relevant specimen types. The result showed all the samples belong to the family Lauraceae. Samples #1 and #3 of the Machilus Nees were identified as Phoebe sheareri and P. zhennan, respectively, they are also known as “Nanmu”. Meanwhile #2 was also referred to as Machilus Nees, but named as “Nanmu with black bark”. Significant differences in anatomical characteristics were determined amongst the three samples; thus, they could not be classified as gold Phoebe sp. Moreover, the practical densities of the samples showed no marked increase relative to the species in literature. Microscopy also exhibited no rare mineral enrichment in the cell lumen or the intercellular space. Results of this study indicated that the three samples do not belong to the category of buried wood or ebony.
This paper concentrated on the production of torrefied without an additional binder from different raw wood materials. The torrefaction and pelletizing was carried out at the Torrec Ltd. pilot plant located in Eastern Finland and its effective capacity was 2,200 tonnes per year. Six different woodchips lots were tested in the pilot runs. The test was to identify whether the pelletizing process requires an additional sealant as a binder. The pelletizing process only exploited condensation water that came about from the torrefaction process. The temperature control range and the holding time were varied, regarding the driving parameters. Finally, quality factors were analysed from torrefied pellets and its raw wood materials after each pilot run. The maximum temperature of the reactor, 260°C, was perhaps too low to manufacture pellets of high energy content. Based on the study, the pelletizing process will not require an additional binder in the future.
The aim of this work is to study the effects of different ages and damage of the oak wood (Quercus petraea Mattusch) in relation to its flash point temperature and ignition temperature, as well as on determination of the ratio of changes in extractives, cellulose and lignin, in the heat loaded samples of 5 - years old oak wood, 160 - years old oak wood, and also 160 - years old oak wood degraded by wood-destroying insects and fungi. The results of the analyses showed that the flash point temperatures were in the range of 357.52°C - 360.63°C.The ignition temperatures were at interval of 398.93°C - 414.92°C. The time to reach the ignition point was at the interval between 344 and 365 seconds. Under the thermal loading of oak wood, there comes to the significant changes, especially in the surface layers. These are, in addition to colour changes, demonstrated the chemical changes of the main components of wood and extractives. Increasing the temperature, there increases also the content of the substances extractable with ethanol and toluene. Increase in their amount is mainly due to the lignin, but partially also due to the polysaccharides decomposition products.
The aim of this present study was to promote the quality of living environment, and create a healthy living environment through advocating for low carbon and green buildings. An additional aim is gaining recognition for wood structured housing, thus gaining recognition in customers and consumption to further promote the green ecological and sustainable development of wood structured houses. This work examined the physical environment indexes and physiological indexes of the participants in three different structure types of housing environment with behavioral analysis (CAPTIV) and environmental data (BAPPU) synchronous test system. The results of the MANOVA revealed a significant main effect for the housing environment indexes with temperature, moisture content, noise, illumination, air flow rate and skin temperature, ECG, and respiration of three different structure types (log, glulam, reinforced concrete). In comparison, the influence of the physical environment factors in both the log structure and the glulam structure housing were better than the reinforced concrete structure housing. It indicated that woody housing environment was benefit to the health of habitants. Participants were interested in the log structure and glulam structure housing environment with joy and comfortable feelings. Different proportion of building environment and interior wooden decoration proportion can influence different cognitive…
WOOD RESEARCH Volume 62, Number 4
This article investigates the material thickness of the individual layer composition influence on the stresses under tension loading. The SolidWorks application was used for tension stress simulations. This simulated course of tensions was carried out for soft and hard materials as a function of their thicknesses. Hard material was represented by beech wood and soft material by aspen wood. Subsequently, the tensile stress and deformation of various two- and three-layered compositions of these materials were analyzed. Based on our results, the soft material was the weakest link; therefore, the ultimate tensile strength of the entire layered material is directly dependent on it. Hard material can withstand greater tensile stress and deformation without breaking, as soft material does.
Utilizing waste decayed wood is an effective method of conservation woodresourceand protection environment.In this paper, the sound absorption property of decayed poplar wood (Populus tomentosa) was investigated by analyzed the changes of microscopic structure, pore characteristics and sound absorption properties. Experimental results indicated that the sound absorption coefficientof decayed poplar woodwas significantly improved compared with the health wood. The components of cell wall were decomposed after decayed resulting in the pit membrane being disappeared, even the cell wall are decomposed and formed new pores. In addition, the pore size and connectivity increased, flow resistivity and sound impedance decreasing for the decayed poplar wood. Those results revealed that propagation path and internal friction between sound wave and cell wall increased, resulting in the acoustic attenuation increasing. The decayed waste woods as a sound absorption material would become possible.
A comparative analysis was performed to determine the density, moisture content, shrinkage, pH, and concentration of potassium and calcium in samples of false heartwood and sapwood from two commercial poplar hybrids. The results showed that the calcium concentration is on average three times higher in false heartwood than in sapwood. In turn, the potassium concentration is on average five times higher in false heartwood than in sapwood. The pH increased from slightly acidic in sapwood to slightly basic in false heartwood. The moisture content is markedly higher in false heartwood than in sapwood. However, density and shrinkage do not differ between the two types of wood. A chemometric model analysis was used to differentiate between the two types of wood by using near infrared reflectance spectroscopy (NIRS) with multivariate analysis. The NIRS-implemented method demonstrated efficiency to discriminate between both types of wood.
The objective of this study was to investigate effects of artificial weathering on color stability of six tropical wood species: Apuleia leiocarpa (Vog.) Macbride, Bagassa guianensis Aubl., Dipteryx odorata (Aubl.) Wild., Hymenea courbaril/Linn., Manilkara bidentata A. Chev., Tabebuia sp. Chemical composition of weathered wood was also studied by FT-IR spectra. With the progressive artificial weathering color of wood changed gradually. Hymenea courbaril Linn. wood occurred the greatest range of the total color change. The largest changes in intensity of the wood color took place at the beginning of artificial weathering process. FT-IR analysis indicated the occurrence of lignin and hemicellulose oxidative changes resulting in formation of carbonyl and carboxyl compounds during weathering. Oxidation products are the main cause of wood surface discoloration. Additionally, changes suggesting depolymerisation of cellulose were identified as well.
The main chemical composition content of Picea jezoensis (holocellulose, lignin, and extractive content) was measured using the traditional chemical experiment method, and the vibrational parameters including of dynamic elastic modulus E, specific dynamic elastic modulus E/ρ, acoustic impedance Z(ω) and sound radiation coefficient R, of the spruce samples were measured using the multi-channel fast Fourier transform analyzer. The relationship between the different components and wood acoustic vibration properties were analyzed by simple linear regression analysis and bivariate regression models. The results showed that the holocellulose content significantly affected on the acoustic properties of the wood. The vibrational properties first increase and then decrease with the increase in holocellulose content. The best vibration properties is achieved when the holocellulose content is 62% to 65%. Lower lignin content and benzyl alcohol extractive content are beneficial in improving the acoustic properties of wood.
The paper deals with the effect of heat treatment of spruce wood (Picea abies (L) Karst.) at the temperatures of 160°C, 180°C and 210°C - on the change of properties that characterize its relation to fire and burning,in particular in the phase called flameless combustion. A test method, which is sufficiently sensitive to monitor these changes, has been used for the evaluation of these changes. The results show that thermally modified spruce wood has positive assessment even in this regard.
In this study, the withdrawal strength of T-shaped joint was investigated through using Finite Element Method (FEM) and Analytic Method (AM). Firstly, the mechanical properties of wood were measured by conducting the experiment. In addition, the influence of friction coefficient between wood interfaces was studied with various size of contact area, direction of grain and pressure. Then, a mathematical model of oval mortise and tenon joint withdrawal strength was established based on linear elastic mechanics. Subsequently, the withdrawal strength of T-shaped joint was analyzed on the basis of numerical method with Finite Element Method (FEM) software. Finally, with the application of the experimental method, comparison and analysis were made between numerical method and analytic method. The results demonstrated that the consistency level between the numerical method and experiment was 83 %, which is more accurate than that between analytic method and experiment 80 %. As a results, the mathematical model was applicable to calculate the withdrawal strength of mortise and tenon joint which can also meet the engineering requirements of wood construction and wooden products structure design. In addition, the FEM applied in the study was more precise than analytic method while the latter was comparatively simple and convenient. These…
Capillary flow porometry and mercury intrusion porosimetry achieved a good agreement in determining the pore size distribution in papers for the top layers of corrugated board. Differences in the papers composition as well as structure can be easily detected by changes in the measured parameters, thus allowing a better understanding their behaviour at processing and use. Water absorption is mainly dependent on the diameter of the large pore and to a lesser extent from the diameter of medium pore, surface free energy of paper and the swelling ability of recycled and bleached pulp fibres.
This paper researches fiber in-situ synthesis of calcium silicate that is made from sodium silicate solution extracted from fly ash, lime milk and fiber and its usage in fine paper. The in-situ synthesis technique was used to prepare man-made calcium silicate loaded in paper. The paper is in line with the copy paper standards. The experiments determined the optimum conditions for papermaking as follows, the pre-processing time of fiber immersed in the silicon solution 6h, pulp freeness 42°SR, the SiO2 concentration of the silicon solution 65.5g/L, the effective calcium concentration milk of lime 175g/L, stirring speed 550r/min, the reaction temperature 95°C, the reaction time 90min. Under these conditions, the filler retention rate in fine paper can reach more than 80%. A scanning electron Microscope-Spectroscopy (SEM-EDX), X-ray diffraction (XRD), infrared spectroscopy (FT-IR) was used to analyze paper products and structure. The results showed that the calcium silicate generated within the cell lumen, cell wall, and other open spaces of the fibers, and good bonding was demonstrated between the filler and fibers.
Resonant method of determining modulus of elasticity and shift and decrement of fluctuations’ operates in Russia to determine elastic-viscous properties of wood (GOST 16483.31-197474). The method is destroying and demanding much time and expenses for manufacturing pre-production models in the form of rectangular bar sized 20×20×300 mm, which requires tree cutting down, severing, sawing, etc.; as a consequence, it has not found wide implementation in the practice of research and, especially, selection of qualitative material for musical instruments manufacturing. The work objective is to conduct basic research on revealing a more effective and precise non-destructive method for identifying Young’s dynamic modulus of elasticity as a basic criterion of standing spruce-tree resonant wood quality with the aim of its selection at an early age and creation of perspective object for woodworking with reference to musical instruments manufacture.
Lignocellulosics fibers and commercially-manufactured-chip (Pinus sylvestris L., Fagus orientalis and Quercus robur L.) with 11% moisture conten twere used for the experiment. The mixingratios of lignocellulosics fibers was 20% which is from okra and tobaccos talks, hazelnut and walnuts hell, and pinecone for each mixture in preformed panel and commercially-manufactured-chip was 100 % for the control sample. A commercial ureaformaldehyde (UF) adhesive was used as a binder. The physical and mechanical properties such as density, thickness swelling (TS), bending strength (BS), modulus elasticity (MOE), internalbond (IB), screw holding ability (SHA) perpendicular to the plane of panel, Janka hardness perpendicular to the plane of panel properties of MDF were measured.The results indicated that all the panels met the general purpose-use requirements of TS-EN. Thus, our results suggest that biomass from different sources can be an alternative raw material for MDF manufacturing process.
In this paper, wood pretreatments were carried out at an ultrasound intensity of 300 W and a frequency of 40 kHz for 60 min, and the ensuing drying process used a temperature of 60 °C. The study analyzed the pretreated wood before and after ultrasonic pretreatment via drying dynamics, electron microscope scanning, and Fourier transform infrared spectroscopy. The results showed that ultrasonic pretreatment successfully improved the effective water diffusivity, decrease the drying time, reduce the amount of extractives on the inner wood pores, and create microchannels in the wood, resulting in improved heat and mass transfer rates. These results indicate that ultrasonic pretreatment is an effective method for the drying of eucalyptus.
The present study was aiming at measuring cutting forces for wood of lesser used species from Mozambique such as Acacia nigrescens Oliv (namuno), Pericopsis angolensis Meeweven (muanga), Pseudolachnostylis maprounaefolia Pax (ntholo) and Sterculia appendiculata K. Schum (metil). Another aim was to use an expeditious method to compare performance of the species when cut. A machinability index calculated using Digraph and Matrix Methods was used for ranking the performance of the species when cut. Two different cutting tools 20o and 30o rake angle were used. Main cutting force in 90°-90° and 90°-0°cutting directions were measured by piezoelectric gauge. The results of the experiments showed that cutting forces followed normal trends to increase with density and decrease with increasing rake angle. The ratio between wood density and cutting forces in cutting directions 90°-90° and 90°-0° were 7 s2m-4 and 17.3 s2m-4, respectively. The most difficult species to be machined was Namuno, whereas the easiest species to be machined was Metil.
The research advances of laser cutting technology were first stated. Then to study the performance of bamboo laser cutting and obtain the optimum technological parameters, we used a laser cutting machine with 60 W power laser tube and observed the magnified kerf shape. We found laser cutting perpendicular to the fiber direction was more difficult than other cutting directions under the same conditions. The notch depth was the deepest by parallel cutting and the notch width was the widest by oblique cutting. When the thickness of laser-cut bamboos was 3 mm, we obtained moderate kerf width, thinner carburization zone and better kerf quality under laser nozzle height 20 mm, cutting speed 30 m.min-1 and laser output power 48 W, which were the optimum technological parameters of bamboo laser cutting.
The paper is focused on area of investment measurement and management in manufacturing enterprises in Slovakia and especially analyses wood processing industry. The aim of this study was to investigate using of certain methods and groups of indicators in investment effectiveness valuation and their possible impact in better business performance. Discounted cash flow valuation is one of several ways of approaching valuation, however, it is a foundation of all other valuation approaches, so we are mainly interested in indicators such as Net Present Value or Internal Rate of Return. We used in the research two-dimensional inductive statistics between categorical variables, the dependence we examined with contingency and we also applied analysis of variance. Our research statistically confirmed that better business performance is significantly dependent on use of certain investment effectiveness valuation methods.
WOOD RESEARCH Volume 62, Number 5
The anatomical structures of both untreated and thermo-vacuum treated (the temperature of 200°C, the duration of 4h and the relative pressure of -0.08 MPa) Szemao pine wood (Pinus kesiya var. langbianensis) and alder birch wood (Betula alnoides) were observated and analysed by light microscopy. The obtained results were as follows. (1) Szemao pine wood with thiner earlywood cell walls and thicker latewood cell walls, which was an abrupt transition from earlywood to latewood, was not susceptible to the thermo-vacuum treatment (TVT) in this test. Only smaller radial cracks were observed in the cross section, and ray parenchyma cells which they were non-lignified cells were partially destroyed. Longitudinal tracheids walls remained intact and were not destroyed. (2) No destruction was also observed except part of the scalarform perforations plates in alder birch wood under the TVT. The results indicated that effects of the TVT on the anatomical structures of woods were slight. In addition, the extractives of both szemao pine wood and alder birch wood were removed, playing an important roles in improving the permeability of wood after the TVT.
Gaharu or agarwood is produced by certain trees in response to fungal infections and wounds. The response is a pathological process that alters the physiological and chemical compounds produced in tree wood, yielding a fragrant resinous material. We investigated the density and hardness properties of agarwood using the drilling resistance method in 25 disks of Aquilaria malaccensis that had previously been inoculated with Fusarium solani. A micro drilling technique was applied in two directions across the diameter of the disks to measure resistance, starting in the part containing agarwood. In addition, hardness properties were determined based on the Janka test and density was measured based on the gravimetric method. We found that hardness properties varied greatly in disks containing agarwood. A low correlation was found between the amplitude of resistance and hardness and density, indicating that other variables beyond density are also involved in the changes of wood properties in agarwood. A strong correlation was observed between hardness and wood density.
The structure of both cambium and the last-differentiated cells from cambium influence the adhesion of bark on wood. In the submitted paper, the bark/wood adhesion is evaluated by means of measuring the shear strength in longitudinal and tangential direction of the wood/bark interface on woody plant beech (Fagus sylvatica L.) during one year. The growing period and dormant period and moisture of the wood/bark interface proved to be important factors influencing the shear strength. The shear strength measured during the dormant period in the greenstate showed values approximately 100% higher than those measured during the growing period. Considering the 12%-moisture, the values of shear strength proved to be circa 300% higher in comparison to the green state. The shear area during the dormant period was led through the zone of the last-created sieve tubes of non-collapsed late phloem, whereas during the growing period the shear area passed through the cambium zone. The structure of shear areas is also significantly influenced by diverse structure of narrow and wide phloem rays.
Dynamic thermo-gravimetric analysis under nitrogen was applied to investigate the thermal decomposition process of wood/HDPE composites (WPC) modified with different amount of ground tire rubber (GTR). Degradation models, including the Friedman and Flynn-Wall-Ozawa (F-W-O) were used to determine the apparent activation energy (Ea) of various materials. Composites with various GTR contents exhibited a similar two-stage degradation process. Initial decomposition temperature (T0) of the composites gradually decreased from 250.1°C to 238.2°C with the increasing GTR concentration, while the peak temperature (Tp) values remained about the same. Kinetic analysis demonstrated an average activation energy decreasing with the incorporation of 5 % GTR within the composites through both methods, but no big difference was observed with further increasing the GTR content from 5 % to 15 %. The established thermal decomposition kinetic parameters allow developing the reutilization of waste tire rubber in composite materials with appropriate loading level.
The article describes the method of evaluation and preparation of fluting liners produced from semichemical pulp of waste wood particle boards (PB) and oriented strand boards (OSB) and after the combination with old corrugated cardboards (OCC) to improve strength properties. The semichemical pulp was obtained by a mildly alkaline boiling process from two fractions of waste PB and OSB. Properties as thickness, bulk density, gurley, tensile strength, tensile index, breaking length, burst index, CMT30 and SCT were monitored on lab sheets 127 g.m-2 and 170 g.m-2. Values of pH and residual NaOH and Na2CO3 were determined in batch leachate.
The dielectric properties of seven wood species from Poland were measured as a function of frequency and grain orientation of wood. Measurements were conducted parallel and perpendicular with respect to the visible grain for specimen cut from sapwood and heartwood, at frequencies ranging from 1 kHz to 1 MHz. Both, relative permittivity and loss coefficient were affected by frequency and anisotropic direction. The most significant influence of wood species on dielectric wood properties was observed below 5 kHz for relative permittivity and below 200 kHz for loss coefficient. The relative permittivity decreases with increasing frequency and loss coefficient increases with increasing frequency (at frequencies above 200 kHz) for all wood species and fiber orientation. Understanding the dependencies between dielectric parameters of wood and other wood parameters at frequency range from 1 kHz to 1 MHz is important when wood is used for electrical insulation or in high-frequency drying.
This study was aimed to investigate the gloss, surface hardness, surface roughness, and color changes of Scots pine that was treated with some chemicals after six months of weathering exposure. Chromated copper boron (CCB), vacsol aqua, and imersol aqua were used as the impregnation chemicals. Scots pine wood specimens were impregnated with 3% aqueous solutions of the chemicals according to ASTM standards.The results showed that while chemical treatment caused a decrease in surface hardness, gloss, and lightness of wood specimens, it increased the surface roughness of the wood before weathering. While the gloss values of all treated Scots pine specimens increased after weathering, the gloss loss was observed for the untreated specimen after weathering. All of the treated and untreated Scots pine wood surfaces were softened after weathering. The chemical treatment caused a decrease of surface roughness of wood after weathering. While in terms of the gloss, surface hardness, and surface roughness changes, the vacsol aqua-treated pine specimens gave the best results. The CCB-treated Scots pine showed the best color stability after weathering.
This paper deals with changes in roughness and crack formation after surface embossing of aspen wood. Embossing was based on pushing a wedge with 45° angle into three embossing depths, i.e. 2, 4 and 6 mm. The surface roughness before and after embossing was evaluated on the basis of the arithmetical mean deviation of the roughness profile, Ra. Surface quality measurements were carried out in perpendicular (transversal), parallel (parallel) and perpendicular/parallel to the wood grain. (Embossment area quality was evaluated by the mean of portion of cracks in embossment). This evaluation was based on a digital image of the embossed area and a subsequent calculation of the portion of the cracked area in relation to the total evaluated area. Increasing the embossing depth has a positive impact on the quality of the embossed surface, i.e. the highest quality was generally achieved with an embossing depth of 6 mm. The worst surface quality was achieved with the perpendicular orientation of the wedge regardless of the direction of the roughness measurement.
Our work on the physical properties of wood in hardwood species, Quercus robur L., Q. petraea (Matts) Liebl., and Q. pyrenaica Willd., for study its use in cooperage, began with the proportion appraisal of bark, sapwood, and heartwood, and its relationship with age, to know and assess the variation thereof in the Galician oaks. To properly perform our study, it was necessary to fell several Quercus trees within the study area (Galicia, NW Spain). In total, 45 trees were selected in 15 different stands located in the Galician provinces of Lugo and Ourense, from which we obtained 45 slices of wood at 60 cm height on the tree trunk. There are many anatomical differences between hardwood and softwood species; however wood parts of a tree system are common to both. The analysis of different proportions of bark, sapwood, and heartwood made it possible to reveal: i) the rapid growth of Quercus pyrenaica gives rise to the formation of large proportion of heartwood in a few years; ii) Quercus petraea has the largest proportion of heartwood, but the studied trees are older and their growth is slower than the other species; iii) Quercus robur has an intermediate growth between the other…
The aim of this study was to investigate the components of volatile by-products released at different treatment temperatures. For this objective, the aldehydes and ketone were trapped in DNPH solution and the aldehyde and ketone derivatives were analyzed by HPLC. The acids and alcohols were trapped in deionized water and analyzed by HPLC and GC. The other volatile organic compounds were trapped on Tenax TA tubes and analyzed by GC-MS. The results showed that there was an increasing trend in the concentrations of aldehydes, acids, and alcohols with the increasing treatment temperature. The heat treatment at higher temperature resulted in more kinds of volatile organic compounds.
In this study, Turkish fir wood (Abies nordmanniana subsp. bornmulleriana) was subjected to two heat treatment process with varying temperatures (150, 180 and 200°C) and durations (2, 4 and 6 h). Some properties of the heat treated Turkish fir wood; mass change, water absorption, volumetric swelling, bending strength, modulus of elasticity (MOE), compression strength parallel to grain, color change and surface roughness have been tested and evaluated by statistical analysis. Consequently, volumetric swelling and water absorption values of the heat treated wood samples reducing. Bending strength, modulus of elasticity and compression strength parallel to grain values were decreased by heat treatment at high temperatures. Additionally, color change and surface roughness values of heat treated wood decreased with weathering compared to those of control samples.
To promote the environmentally friendly properties of wood plastic composites (WPC) fabricated via a polyvinyl chloride resin matrix, the effects of different amounts (0, 5, 15, 25, and 35 phr) of expoxidized soybean oil (ESO) on mechanical strengths, thermal stability, melting processing properties, and water absorption of the composite samples were studied. The results show that the tensile strength of WPC decreased. However, the elongation at break, water absorption and thickness swelling rates increased, especially for ESO addition amounts beyond 15 phr. The flexural strength and modulus of WPC followed an upward trend initially (at 5 phr ESO), then switching to a downward trend. The initial thermal stability at the first thermal decomposition stage and the melting processing temperature of the composites ewere effectively improved with the increase of ESO level. Compared to the samples without added ESO, the maximum thermal decomposition temperature (Tmax1 and Tmax2) values of the composites increased by 31°C and 8°C, respectively, while the melting processing temperature of the composites significantly decreased by 24°C corresponding to an added level of 35 phr. In summary, the WPC samples with 5-15 phr ESO addition not only effectively retained their the mechanical strengths and water absorption stability, but also…
The paper deals with the calculation and analysis of cutting force and input power when crosscut sawing with a chainsaw. For obtaining and evaluating the results, we have used empirical relationships and the values of appropriate coefficients given by the literature. After the evaluation we have gained the theoretical knowledge of the impact of a tree species and its moisture on cutting force intensity and input power. Tree species have a strong influence on cutting force; the harder the tree species is, the greater cutting force is required. Input cutting power is calculated from the cutting force that is why the impact of a tree species on input power is as big as on cutting force. It has been confirmed that the cutting force and cutting input power are affected by wood moisture content, as well.
The article presents calculation methods for flat-crush resistance (FCT) of honeycomb paperboard. The calculations were made on the bases of mechanical properties of the material that is, paper used for core production and shape of its cells. The methods presented in the article allow to calculate the FCT for the cores with the cells of the theoretical hexagon shape as well as of the real shape. The correctness of the methods proposed was verified by the comparison of calculation results with the results of FCT measurements for boards of different core height.
The relevant standards for glueline shear strength testing were summarized and analyzed in this paper. Depending on these existing test standards, the resulting stress in glueline is not pure shear stress, but a combination of shear and normal stresses. In order to overcome this deficiency, a symmetrical structure was proposed for making samples. Some comparative testing was accomplished by using these symmetrical samples, the results showed that the normal stress could be avoided during testing. These results were also confirmed by finite element method (FEM), the simulation results showed that the shear stress in glueline was uniform.
WOOD RESEARCH Volume 62, Number 6
The derived model describes equilibrium in wood as it is placed it water. The model expresses the equality of density of water and coupled term of basic density and moisture content on the other side. The other part of the model is its extension to water in wood. The maximum moisture content is derived from the view point of density definition. Then Archimedes’ principle enables to measure bound water maximum moisture content. The model is applicable to wood of arbitrary wood species and also for different kind of materials as it is documented in the embedded table.
This study describes the accumulation of secondary wall layers of the fast-growing Populus×euramericana cv. ‘74 /76’ during the active phase by the methods of polarized light microscopy analysis and computer simulation technology. The results showed that the secondary wall layers of Populus×euramericana cv.‘74/76’ appeared light and shade stratification during the differentiating phase, and the wall layers corresponded to S1, S2 and S3 layer from outside to inside respectively. The S1 and S2 layer of wood fibers were differentiated in May, and the S3 layer was appeared until the July. In addition, the thickness of the three layers all showed a gradual increasing trend. The accumulation process of the secondary wall layers was visually displayed by the computational simulation technology during the active period.
This paper describes the chemical and physical properties of Pinus leiophylla, P. montezumae and P. Pseudostrobus timber by-products (wood chips, bark and wood-bark). The physical features determined were the initial moisture content, bulk density and calorific value whereas the determined chemical characteristics were pH, inorganic compounds, inorganic compounds microanalysis, extractives, lignin, and holocellulose. Such by-products were collected in the industrial complex at the Indigenous Community of Nuevo San Juan Parangaricutiro, located in Michoacán, México. The initial moisture content of the samples varied from 33.6 to 56%, while their bulk density ranged from 0.19 to 0.31 g.cm-3. The calorific value for the wood residues of the three different species of pines varied from 17.95 to 18.93 MJ.kg-1. Regarding their chemical characteristics, barks were more acid than woods, and in general, the inorganic content was lower in woods than in barks. According to the X-ray microanalysis, the major inorganic compounds found in ash were calcium, magnesium, and potassium. No heavy metals were detected at all. For the three pine species, extractives levels in barks were higher than in woods. Also, barks contained a higher concentration of lignin than woods. The highest holocellulose content was found in wood residues rather than in barks.…
Wood preservatives are typically chemicals that granted antimicrobial properties to timber, while leachate is the liquid that percolated through accumulation of waste materials. Clostridium butyricum NCIMB 7423 was used to ferment leachate with 1.15 L working volume under anaerobic condition at 37°C and pH 6.5.This research focuses on preserving rubber wood by acids and salts derived from the fermented leachate. First and second set of treatment were performed to study fungal resistance of wood treated by acids and salts respectively. Biological decay test was conducted using Phanerochaete chrysosporium to determine the percentage of mass loss for different preservatives. The salt concentration of 0.5 M sodium acetate and sodium butyrate shows satisfactory result to preserve rubber wood. Thus, the salts derivative could be converted into rubber wood preservative. This research will reflect to material from waste to wealth and support sustainable technology.
The properties of cork are strongly dependent on its cell wall properties. Thus, it is very important to characterize the cork cell walls in order to understand structure-property relationships. The reproduction cork tissue from Quercus variabilis Blume was examined with field-emission scanning electron microscopy to detect the structural characteristics of the cell walls. Several noteworthy anatomical features were present in the cells of Quercus variabilis cork. In most instances, the inner wall of cork cells was not smooth and showed an irregular surface. Solid deposits of various shapes were observed in the inner surfaces of the cell walls. Cell walls of cork tissue had severe corrugations in transverse and radial sections. Trabeculae were found for the first time in the cork tissue of Quercus variabilis Blume. They extended across a few cells, with a rod-like form. Nanoindentation techniques provide a new view of the mechanical properties of the cork cell walls. The hardness of cell walls of untreated and boiled reproduction cork from Quercus variabilis was 0.54 GPa and 0.51 GPa. The elastic modulus was 11.47 GPa and 11.81 GPa, respectively. Boiling treatment of cork could improve mechanical properties of cell walls.
Horizontal lap-joint trials were set up using eleven different wood species representing a wide range of natural durability. Coated and uncoated lap-joint specimens as well as non-jointed reference specimens were exposed for up to 20 years and evaluated with respect to decay, formation of cracks and performance of the coating. The tropical wood species Tatajuba, Cedrorana, and Dark Red Meranti performed still very well and also some Europe-grown softwoods with coloured heardwood were still in good shape. The lap-joint set up turned out to be a method that can be used also for determining the durability and performance of untreated naturally durable wood, but suffered from several drawbacks such as time-consuming and costly specimen preparation, difficult to detect onset of decay, and generally long exposure times needed for a reliable durability assessment. Cracks were often the starting point for internal decay, but did not exclusively occur in the lap area.
There are notable differences between the 2-D standardized surface roughness parameters depending on the position of the profil of the surface roughness eavluation of natural wood.Therefore it is fundamental to determine which parameters are the least dependent on the position of the measured profil. The dependence of the standardized roughness parameters on the different measuring positions varies. We observed the smallest average dependence at the arithmetic average roughness (Pa) parameter of the P-premary profile, and at the Mr1 (threshold as the minimal Asperities’ height distribution AHD )and Mr2 (threshold as the maximal AHD) parameters and "reduced" height peak amplitude (Ppk) was more dependent. The greatest deviation occurs in the mean roughness depth (Pz), maximum height of the profile (Pt), and the maximum roughness depth (Pmax) values. These three parameters whoed the highest differences in function of the measuring positiions.
This study was conducted to investigate some surface properties of wood specimens of heat treated Scots pine (Pinus sylvestris L.) after weathering such as surface hardness, surface roughness, gloss, and color changes. Heat treatment of Scots pine wood was carried out by hot air in an oven for 1, 2, and 3 hours at 210, 220, and 230°C. The results showed that generally surface hardness losses of heat treated Scots pine wood were lower than that of un-heated Scots pine wood after weathering. Heat treated Scots pine wood gave smooth surface after weathering. Except for heat treatment at 230°C for 1 and 2 hours, heat treatment resulted in better glossiness compared to un-heated Scots pine wood after weathering. According to the test results, while heat treated Scots pine wood become lighter after weathering, un-heated wood become darken after weathering. In general, heat treated wood surface to become reddish and yellowish after weathering.
Enzymatic hydrolysis of extruded wheat straw with addition of sodium hydroxide and calcium hydroxide
Extrusion pretreatment of wheat straw in a single screw extruder was investigated in terms of effectiveness of enzymatic hydrolysis and the formation of fermentation inhibitors. The effect of sodium hydroxide in extrusion pretreatment was compared with calcium hydroxide. The accessibility of wheat straw structure to hydrolytic enzymes increased with NaOH and Ca(OH)2 loadings, whereby more with the addition of NaOH. With 6% w/w of NaOH loading, the conversion of polysaccharides was 76.1% and with the same Ca(OH)2 loading it was 47.3%. The conversion of polysaccharides with 12% w/w of Ca(OH)2 loading was 66.6%. Without alkali in extrusion pretreatment, the conversion of polysaccharides was only 36.7%. The polysaccharides conversion of original extruded wheat straw was about 1.5 to 3.3% higher in comparison to washed extruded wheat straw. Fermentation inhibitors such as lignin, acetic and formic acid are primarily formed in the presence of alkali during extrusion pretreatment, most of which was lignin. Alkaline extrusion is a suitable method for pretreatment of lignocellulosic biomass.
This work evaluates the extraction of sugarcane bagasse (SCB) and soft wood (SW) celluloses with alkali treatment followed by bleaching process using sodium chlorite at different time. The influence of extraction time (2 hrs and 4 hrs) on the thermal, crystallinity and morphological properties was investigated. The extracted celluloses were analysed by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The aromatic skeletal vibrations of lignin and hemicellulose confirmed the extraction of cellulose which varied extraction time. TGA analysis shows that the untreated SCB degrade earlier than their respective celluloses and the prolonged treatment affects the onset of main degradation. XRD results showed that extracted celluloses had greater crystallinity index, and was affected at prolonged time due to long range destruction of cellulose crystals. The SW revealed a complex behaviour due to the dominated lignin content as revealed from chemical composition analyses.
Wood preservation technology has been using a lot of synthetic preservatives for a long time. However, some disadvantages have been recorded such as environment quality degradation and killing more untargeted wood destroying organism than targeted one. Recently environment quality maintenance has been required causing a significant change in general wood processing technology and wood preservation paradigm. In terms of wood preservatives has changed from synthetic to natural wood preservatives application. Sengon is the fast growing wood species chosen in Indonesia to fulfill national and international wood demand. Unfortunately this wood species is class V of wood durability and has to be treated with preservatives. Glued wood products such as plywood, lamination, particleboard and fiberboard use low durability wood such as sengon. The objective of this research is to know the adhesion strength of sengon wood after treatment with the natural preservatives. This research was conducted by wood adhesion block method. The fast growing sengon plantation wood was chosen since this type of sengon wood was classified as low grade of wood quality (Class V). This type of wood had high portion of sapwood which was susceptible to wood destroying organism and absence of natural preservatives. The sources of natural wood…
This study was performed to investigate some surface characteristics such as surface hardness, surface roughness, and color changes of heated and varnished Oriental beech (Fagus orientalis Lipsky) after accelerated weathering. Heat treatment of Oriental beech wood was carried out by hot air in an oven for 0.5, 1, and 1.5 h at 210, 220, and 230°C. After heat treatment, Oriental beech wood specimens were varnished using a polyurethane varnish. The results showed that accelerated weathering generally caused increase of surface hardness of Oriental beech. Surface roughness and total color changes of heated and varnished Oriental beech were lower than only varnished (control) Oriental beech after accelerated weathering. Heated and varnished Oriental beech wood gave better surface characteristics than only varnished oriental beech after accelerated weathering.
The paper deals with the possibility of floating flooring ignition due to radiant heat. Samples of floating flooring with dimensions of 100 ± 1 mm x 100 ± 1 mm and thickness of 6 mm were thermally loaded by different densities of external heat flux. The flaming combustion was initiated either solely by means of radiant heat, or in combination with electric spark igniter. Cone calorimeter was used for the determination of the critical heat flux. Time to ignition for each sample was recorded and the obtained data were used for the calculation of the critical heat flux density.
Recombinant bamboo is a new kind of bamboo-based panel material that has been widely used as a structural material. However, there are many problems in the sanding process of this material. This study analyzes the impacts of sanding parameters on sanding force, sanding active power and sanding efficiency in sanding recombinant bamboo, which is meaningful for improving the sanding quality, reducing power consumption and collocating the sanding parameters more reasonably. Granularity, feed speed, sanding speed and setting sanding thickness have different influences on sanding force, sanding active power and sanding efficiency, and the grey relevancy results show that feed speed has the most significant effect on sanding force, sanding active power and sanding efficiency. The actual sanding thickness is smaller than setting sanding thickness, and the difference between actual and setting values (ΔTs) is influenced by sanding parameters. Taking a comprehensive consideration of ΔTs and standard deviation of actual sanding thickness, determine the optimum schemes according to the method of fuzzy comprehensive evaluation.
Recombinant Bamboo is a newly bamboo material which breaks through the traditional processing mode, and its excellent physical properties can fully replace the wood widely used in furniture manufacturing. In this paper, take the classic back chair for example, in order to research the application of recombinant bamboo material in the furniture, using ANSYS finite element analysis software to compare the stress and deformation of recombinant bamboo, rosewood and elm under stress states. Meanwhile, in order to find out which leg shape is most suitable for the back chair of recombinant bamboo, the impact of the current mainstream three legs on the mechanical properties of the back chair is analyzed. Moreover, the parametric design method can work out the optimum size of legs and seat which are the most important design elements of back chair. This provides an evidence-based and effective method for furniture design.
Volume 61 (2016)
WOOD RESEARCH Volume 61, Number 1
Beech wood (Fagus sylvatica L.) was modified with aqueous solutions of methylated N-methylol melamine (NMM) and a metal-complex dye and the water related properties were determined. Wood blocks, treated to the highest weight percent gain (WPG), attained approximately 5 % cell wall bulking and 30 % anti-swelling efficiency (ASE) after ten cycles of water saturation and drying. The metal-complex dye was stably fixed in the resin matrix and was hardly washed out. The equilibrium moisture content of the modified samples related to the dry mass of untreated beech wood (EMCR) was not considerably reduced compared to the EMC of the control. The maximum swelling of the modified samples as a result of vapour sorption was only reduced above 65 % relative humidity compared to the control. Capillary water uptake of wood was significantly reduced by the resin modification. The results indicate the potential of the combined modification to improve the water related properties of wood.
Electrical and dielectric wood properties are used in many applications. Wood parameters such as resistance, conductivity, complex impedance can be used e.g. for determination fungal decay, moisture content and density or for defects detection. In this work, the complex impedance of seven wood species was measured for frequency range 10 Hz - 1 MHz. The specimens were cut from sapwood and heartwood and measurements were conducted with parallel and perpendicular orientation of the electrical field with respect to the visible grain. The impedance of various wood types differs significantly for frequencies below 2 kHz. Therefore, for wood samples classification, the complex impedance values measured in frequency 1.1 kHz were used. Three different classification methods were used for clustering. Results show that the impedance can be a useful parameter for wood differentiation and membership of each group depends on number of clusters.
In this work, we are interested to incorporating acoustic comfort in buildings by using bio-based materials. More specifically, this work aims to determinate experimentally the sound absorption coefficient (α) and the sound reduction index (R) in three different samples. The first sample consists of Aleppo pine wood (Pinus halepensis) with two different configurations (solid wood and laminated timber wood). The second sample consists of a black agglomerated cork (suber) with two different thicknesses. The third sample consists of sandwich assemblies obtained by superimposing two wooden layers (solid or laminated timber wood) bonded with an inter layer cork. In this experimentation, we have used Kundt tube to determine sound absorption coefficient and AcouSYS V2.0 software to predict the sound reduction index. The obtained results showed that the first parameter (α) is influenced by the thickness of material. The second parameter (R) of symmetrical and asymmetrical sandwich assemblies of solid laminated timber wood with an interlayer of black agglomerated cork even shows good performances.
Test methods evaluating wood flame retardant efficiency are comprised of a parameter which is often considered to be an evaluation criterion and its calculation includes the weight of the test specimen or takes into account the change of its weight during the test. In this case, the overall result may be affected not only by the weight of the test specimens, but also by their density. Our aim is to observe the influence of density while evaluating the efficiency of wood flame retardants.
Heat-treated of Oriental beech (Fagus orientalis L.) and Scots pine (Pinus sylvestris L.) woods were carried out by hot air in an oven for 1, 3, and 5 hours at 205, 220, and 235°C. After heat treatments, some surface properties such as color and gloss changes of both wood specimens were evaluated. Our results showed that heat treatment caused decrease in gloss values of Oriental beech and Scots pine wood specimens. Higher treatment temperature and duration resulted in higher gloss loss of wood specimens after heat treatments. Heat-treated wood became darker tonality, especially; it became more darkening after 3 and 5 hours heat treatments. Generally according to our results, Δa* and Δb* decreased after heat treatments. Oriental beech wood tended to become less reddish than Scots pine after heat treatments. Δa*, Δb* and ΔE* of heat-treated Oriental beech and Scots pine decreased with increasing treatment temperature and duration.
The aim of this research was to determine radial variations of some wood properties from natural and plantation trees of Alnus glutinosa. Oven-dried wood density (WD), fiber cell features, and annual ring width (ARW) were determined in radial positions of stem at breast height of tree. The results showed that the cultivation methods had significant influence on the fiber length (FL), fiber diameter (FD) and ARW. The effect of interaction between radial position and cultivation methods on anatomical features was not significant, except for cell wall thickeness (CWT). Fiber cell features and WD increased with distance from pith for both cultivations trees. The ARW decreased with increasing the cambial age in both cultivation methods. The average of FL and ARW in plantation trees was higher than those in natural trees. Widest FD was found in natural forest. There were significant relationships between ARW-WD and WD-FD for natural forest and between ARW-WD, ARW-CWT and WD-FL for plantation forest. About 67 % of WD variation in natural and plantation trees were related to FD and ARW, respectively. Due to high FL and ARW, wood from planted trees could be suitable for paper production than wood from natural trees.
Wheat straw is an abundant and readily available lignocellulosic material potentially suitable for the second generation bioethanol production. Steam explosion was investigated as a suitable pretreatment method. Effect of steam explosion temperature on wheat straw enzymatic hydrolysis was investigated. Optimum steam explosion temperature at around 200°C was determined based on concentration of monosaccharides in hydrolysates, conversion of cellulose and xylan and yield of monosaccharides from wheat straw. This corresponds to creating conditions resulting in sufficient damage to the lignocellulose structure which leads to higher enzyme accessibility. Lower temperature does not enable sufficient enzyme accessibility while excessively high temperature results in significant breakdown of monosaccharides and lignin and creation of inhibitors. The amount of originated inhibitors was also determined for each studied steam explosion temperature.
The objective of this study was to determine prehydrolysis process on kraft and soda pulping process. Optimum cooking conditions were determined by different alkali concentration and cooking period. Oxalicacid was used to hydrolyzechip before cooking. Prehydrolysis proces increased the yield and viscosity of pulp. Incontrast, mechanical properties of paper were not changed significantly. Optical properties were decreased due to lignin content.
In this case, [Amim]Cl, [Bmim]Cl and [Emim]Ac were used to dissolve ball-milled triploid poplar, and the cellulose-rich preparations were subsequently recovered via incubation in 5 % NaOH aqueous solution and filtration. After the stepwise pretreatments, the carbohydrate content in the cellulosic residues increased to 73.3, 73.6 and 79.0 %, respectively, from 66.1 % in that with sole alkali fractionation. In comparison, the treatment with [Emim]Ac incurred transformation of cellulose I to II, which was favorable to enhance the alkaline fractionation for lignin extraction and disruption of biomass intact structure. After reconstitution, the digestibility of the three cellulosic preparations was all improved, yielding 1.3-fold higher fermentable sugars than that without IL pretreatment (67.2 %). These results indicated that the stepwise pretreatment with ionic liquid and alkali was effective for disrupting the intact structure of plant cell wall, and improving the productivity of bioethanol from lignocellulose biomass.
The aim of this study was to investigate the influence of moisture content on some orthotropic elastic properties of Oriental beech (Fagus orientalis). The elastic properties investigated include EL, ER, ET, νLR, νLT, νRL, νRT, νTL and νTR under compression. Compression strength in all orthotropic directions was also studied. Specimens were cut from sapwood of beech logs and sorted into four matched MC groups. Clear wood samples were conditioned at 20°C and 50, 65, 85, 95 % RH and subjected to compression tests. A digital image correlation technique was used to capture the strains during testing. Young modulus, Poisson ratios, and compression strength were calculated and compared for all orthotropic directions. Results indicated that Young modulus and compression strength of the samples tested were strongly affected by moisture content. Poisson rations seem to less sensitive to the MC changes.
In order to improve the quality of human being's living and working environment, different types of wood structure building, ecological architecture and green building are advocated due to their lots of advantages. This study compared three types of houses in different weather conditions on people's psychological and physiological indexes. The results showed that the temperature, electrocardiograph, heart rate and respiratory rate of people in different types of housing environment are different. Most of the physiological indexes in structural glued laminated and wood structure environment were better than those in steel and concrete structure environment, and most of the physiological indexes in structural glued laminated environment were better than those in the timber structure environment. It means that subjects of the test are easy to had comfortable and relaxed feeling in the glued laminated and timber structure environment. This provided theoretical support for the use of the product by scientific and efficient ways, and guidance for design and application of the construction of the wooden structure environment in the future.
Acoustic is a fundamental topic in large environments often characterized by poor sound quality such as dining rooms or open space offices. The paper reports the development and testing of sound absorbing poplar plywood for the acoustic improvement of such spaces; prototypes were designed aiming at acoustic performance and lightness, as an alternative to other acoustic woodbased panels currently on the market. The experimentation ranged from the testing of small specimens to the validation of prototypes in end-use dimensions. Developed panels achieved high sound absorption peaks in the low frequency range (sound absorption coefficient α = 0.80 at frequency of 315 Hz). Prototypes installed on the walls of a dining room reduced significantly its reverberation time (RT60); room users, investigated by a questionnaire, perceived a high acoustic improvement. On the whole the designed products resulted effective sound absorbers; their industrialization can represent a valuable niche for poplar plywood producers.
The aim of this paper is to compare the results of evaluation of mechanical properties of timber by visual assessment, two grading machines, three devices for measuring in-situ and destructive tests. The most important result is the comparison of static and dynamic modulus of elasticity of timber, and further comparison of strength classes obtained by different measuring methods.
An experimental program was undertaken to investigate the effectiveness of carbon fiber reinforced polymer (CFRP) plates as flexural reinforcement of glued laminated timber (glulam) beams. Beams with and without reinforcement were tested up to failure in a four-point bending configuration. A comparison between the flexural behaviuor of control unreinforced beams with reinforced beams is shown and discussed. The results demonstrated increase in strength, stiffness and ductility when CFRP plate is bonded at tension side of cross section. Research findings indicated that the use of proposed reinforcing solution improves utilization of the compression characteristics of timber. Based on the experimental observations, a theoretical model is developed to predict the ultimate moment capacity and bending stiffness of CFRP-reinforced glulam beams.
The present paper describes results of recent research aimed to make high wear resistance cutter for machining of wood-based materials. Medium density fibreboard (MDF) was chosen for wear test because it is quite abrasive, ease blunts edges of cutters, is inhomogeneous material: contains glue and different mineral particles. It is well known that cutting particleboard results wearing out of cutter faster than machining of natural wood. Because of this, experimental cutters made by surfacing using submerged arc welding (SAW) technique and prepared material powder mixture spread on the surface of cutters blank, were introduced in this research. Suggested material powder mixture ensured obtaining the high alloyed and wear resistant surface layer on the cutting edge of cutter. The wear performance of experimental and commercial cutter was accomplished on the typical industrial thickness planer with a face milling cutterhead using MDF as workpiece. Wear of experimental cutters showed very similar performance as commercial cutter made of high speed steel HSS18.
This paper deals with roughness change and crack formation after surface embossing of aspen wood. Embossing was carried out with three various shapes of embossing wedges (convex, concave and with 45° angle). The embossing was realized with two temperatures, 20 and 160°C. The surface roughness before and after embossing was evaluated on the basis of the arithmetical mean deviation of the roughness profile, Ra. Surface quality measurements were carried out in perpendicular (transversal) and parallel (longitudinal) direction in relation to wood fibers. Embossment area quality was evaluated by the mean of portion of cracks in embossment. This evaluation was based on digital image of embossed area and subsequently calculation of portion of cracks area in relation to total evaluated area. Elevated temperature has a positive effect on the quality of the surface, because of roughness decrease. However, the increase in temperature causes a growth in the proportion of cracks on the embossed surface.
WOOD RESEARCH Volume 61, Number 2
Wood fiber is a porous biomass material, which has a strong adsorption ability for the PM (particulate matter) emitted by diesel engines. Through the SEM experiments, the fact that the pits of micron wood fiber after heat-treated can adsorb lots of ultrafine particles (aerodynamic diameter is less than 1μm) is shown clearly. In simulation, the particle concentration equations and fibrous filtration theory are applied. The collection media around pits is assumed as a cylinder. The simulation results show that the pits have relatively lower collection efficiency for the particles within the diameter from 0.4 to 0.6 μm. Out of the range of 0.4 to 0.6 μm, the collection efficiency increases rapidly, which implies that the pits have higher collection efficiency to filter the particles with the diameter out of 0.4 to 0.6 μm. Among all the affecting factors on collection efficiency, the reduction of permeate flow rate and the addition of tracheid wall thickness improve the collection efficiency. However, exhaust temperature has negligible influence on the collection efficiency.
The aim of presented work was to verify a possible application of nanofibre polyvinyl alcohol (PVA) textiles doped with commercially available biocides for chemical preservation of wooden materials. Fungicide efficacy of biocides based on Propiconazole, Tebuconazole, IPBC was evaluated on Norway spruce samples (Picea abies Karst. L.) 25 x 25 x 4 mm covered by the nanofibre textiles, against the wood destroying fungus Coniophora puteana during 28 days. Decay resistance of spruce samples with the fungicidally treated layer was valued on the base of weight loss (Δm) criteria. The durability of spruce samples significantly increased after incorporation of fungicides into the nanofibre textiles (Δm from 0.2 to 3.7 %), but the influence of the stabilization process was also reflected.
Wood preservation technology has been using synthetic preservatives for a long time. However, some disadvantages have been recorded such as quality degradation of environment, killing more non target wood destroying organism. Since environment quality requirement has been up lifted, then general wood processing and wood preservation paradigm has to change from utilization of synthetic to natural wood preservatives. The new natural wood preservatives have their own properties and influence differently on wood adhesion. Wood adhesive based products such as plywood, lamination, particleboard and fiberboard use wood waste consisting of all kind of processes wood such as naturally preserved wood. The objective of this research is to know the effect of naturally wood preservatives on wood adhesion properties. This research was conducted by wood adhesion block method. The fast growing teak plantation wood was chosen since this type of teak wood was claimed as low grade of wood quality. This type of wood has high portion of sapwood which is susceptible to wood destroying organism. The source of natural, local wood preservatives are gadung tubers, pulai bark and kumis kucing leaves. The wood adhesive used was bio-industrial PVAc in the form of glue paste. Extraction procedure of natural wood preservatives followed…
This study investigated the bonding strength development of furfurylated, N-methylol melamine (NMM) modified and thermally treated birch veneers glued with hot curing phenol formaldehyde (PF) adhesive in different pressing (20, 160 s) and open assembly times (20 s, 10 min). For testing, the automated bonding evaluation system ABES was used with 2 N.mm-2 applied pressure at 130°C. The bonding strength of both modified and unmodified samples increased significantly by prolongation of the pressing time from 20 to 160 s in all cases and for both open assembly times. A deviation was observed for the samples treated at 220°C and at 20 s open assembly time. With the exception of NMM modified veneers, bonding strength did not change significantly by increasing the assembly time in the case of 20 s pressing for both modified and unmodified samples. At 160 s pressing time, extension of the assembly time developed a better bonding for controls, NMM modified and thermally treated veneers at 180°C. The combination of 10 min assembly time and 160 s pressing time proved as the optimal bonding condition for controls, NMM modified and thermally treated veneers at 180°C while the highest bonding strength was noted in 20 assembly time and…
The effect of silica and calcium carbonate pigments, polyvinyl alcohol and cationic starch binders combined with high-cationic polymers on physical-chemical and printing properties of coated papers were studied. The best printing properties were obtained with coating colour based on silica. Colour gamut significantly improved when the inkjet ink contact angle decreased below 15°. The water fastness was influenced with specific charge density of coating colour. Application of silica provided papers with the largest inkjet ink wetting, colour gamut area, print sharpness and surface roughness. By using of polyvinyl alcohol a high colour gamut area was reached but it resulted in a low print sharpness in comparison with cationic starch. High-cationic polymer poly-DADMAC showed a more significant effect on all printing properties of coated paper in comparison with SMAI 1000. The final inkjet print quality depends on structural and chemical properties of coating.
This study aimed to investigate the fiber morphology, crystalline structure and mechanical properties of heat-treated bamboo. Moso bamboo was treated by superheated steam at 120, 140, 160, and 180ºC. Fiber morphology and crystalline structure of heat-treated Moso bamboo were researched by transmission electron microscope and X-ray diffraction. The mechanical properties of heat-treated bamboo were tested in the paper. The result showed that the relative crystallinity and length-width ratio of heat-treated bamboo were increased with increased temperature. The elastic modulus of bamboo was increased as the temperature rose from 120 to 140ºC. and then decreased with higher temperature, which was associated with the increase of the crystallinity.
In the paper the results of exceptional experimentation are presented, which focuses on the long-term loading of metal plate connected wood trusses. The uniqueness of research project is given by real dimensions of long-span samples and by the term of loading over one year. The aims of long-term experimentation were detection of two main parameters. The magnitude of additional deflections and time of load action needed for their development. In the paper the deflection curves are presented, namely time dependence of deflections. In the paper the recommendations for producers of metal plate connected wood trusses and for structural engineers are mentioned. The purpose of that research project is to increase the safety and reliability of timber load-bearing structures.
The strength of the furniture corner-joints in pine remains unknown, and the lack of information restricts its use in furniture industry. Therefore, the aim of this study is to optimize the strength of L-shaped corner dowel joint in pine under compression loads using finite element analysis (FEA) with Taguchi method. By adopting a L9-34 Taguchi orthodoxy array (OA), four experiment factors (i.e., structure style, tenon length, tenon diameter, and tenon gap), each at three levels, were carried out to determine the optimal combination of factors and levels for the von mises stress using ANSYS software. The results of Signal-to-Noise ratio (S/N) analysis and the analysis of variance (ANOVA) revealed that the optimal L-shaped corner dowel joint in pine is 45° Bevel Butt in structure style, 24 in tenon length, 6 in tenon diameter and 20 mm in tenon gap.
This study examined the mechanical properties of Turkey oak (Quercus cerris L.) wood before and after combined steam and thermal treatments under vacuum conditions. Wood was steamed at 100 to 110°C and thermally treated under vacuum at 160°C by the press-vacuum or thermo-vacuum process. Treated material was characterized in terms of the modulus of elasticity (MOE) and compression strength of heartwood and sapwood. The MOE was established using a nondestructive technique based on the measurement of ultrasonic pulse propagation. Results differed depending on the treatment or combination of treatments, and showed that the steaming process strongly affected the MOE. Thermo-vacuum treatment increased the compression strength, whereas steaming had the opposite effect.
The main goal of this study was to improve mechanical and physical properties of particleboards made from vine (Vitis vinifera L.) prunings by addition of reinforcement materials. In Turkey, there are 462.000 hectare areas for vine cultivation. Annually, approximately 2.345.000 ton vine pruning parts residues are remained. Every season, large quantities of vine prunings are left as by-products in the fields, and unfortunately they are not utilized properly by the related industries. In this study, vine prunings and particles were used as raw material for three-layer flat pressed particleboards. Cord fabric fibre (CFF) (mixed), Cord fabric (CF) (sandwiched), plaster mesh (PM) (sandwiched), polyester fibre (PF) (sandwiched) were used as reinforcement materials. A commercial urea-formaldehyde (UF) resin was used as binder. Small size experimental panels (56x56x2 cm) were manufactured. Some physical properties (like, thickness swelling (TS), density, moisture content (MC) and mechanical properties (like, modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB) perpendicular screw-holding (PSH, ⊥), lateral screw-holding strengths (SHS, //), and tensile strength parallel to surface properties of panels were determined. The results indicated that some properties of the reinforced panels can give satisfactory values compared to control (non reinforcement) panels. Generally the reinforcement materials increased the…
A means for selecting the optimal process parameters for the laser cutting of recombinant bamboo, based on the design of experiments (DOE) approach, was presented. Recombinant bamboo with thicknesses of 5, 10, and 15 mm was cut by a CO2 laser. The parameters investigated were the laser power, air pressure, and cutting speed. The results were compared using a number of process responses which define the efficiency of the cutting, including the upper kerf (UK) width, lower kerf (LK) width, and the ratio of upper-to-lower kerfs. Mathematical models were developed to establish the relationship between the process parameters and response parameters; special graphs were drawn for this purpose. Finally, a numerical optimization was performed to find out the optimal process settings to achieve a minimumupper-to-lower kerf ratio.
Oak wood is characterized by a high resistance to effects of biotic factors and thereby it is often found in archaeological excavations. While lying over many years in the wet environment, the wood turns black as a result of reaction with iron compounds. Archaeological oak is a valuable raw material. In this paper selected mechanical and chemical properties of a thousand years archaeological oak were investigated. Then the archaeological oak properties were examined and compared with the contemporary oak wood. Archaeological oak wood as well as contemporary oak wood has a directly proportional relationship between MOE (modulus of elasticity) and wood density, and similar relationships between wood density and compressive strength, bending strength, content of mineral substances. Contemporary wood of the same density as the archaeological oak wood would show significantly higher mechanical properties.
In this study particleboards were manufactured from mixtures of corn stalks (Zea mays indurate Sturt.) and industrial woodchips at several ratios. The corn stalks and industrial wood particles were mixed at ratios 0, 25, 50, 75 and 100 % respectively. The suitability of corn stalks chips for particleboard production was examined. Urea formaldehyde resin was used as a binder in 3-layers particleboards. Produced panels were tested for certain mechanical and physical properties. The manufactured boards were tested according to EN standards. In addition, the chemical properties of corn stalks were evaluated. Experimental results indicated that increase in corn stalk chips in the mixture generally diminished the mechanical and physical properties.
The relation between the mechanical properties of input materials and the smoothness of material flow from a storage bin, cohesion variability of the compressed powder mixtures, and pelletization process were studied. Three material types were examined: Pyrolysis char from biomass – spruce wood (Picea abies L.), compost and spruce sawdust. Increased input material compressibility and cohesion affected the resulting durability and hardness of the pellets. Additional important material parameters affecting the pelletization process and final pellet quality include flowability and wall friction angle: Pellet durability and hardness increases with decreasing flowability (shift to the cohesive materials mode) and wall angle of the incoming materials. Those parameters are taken into account when designing conveyors. Application of the Quality by Design (QbD) approach to the prediction of behaviour in the pelletization process is outlined. The feasibility of inferring acceptable pelletization process behaviour from the mechanical-physical properties of the input materials is demonstrated.
Hydrothermal carbonization (HTC) is a chemical pretreatment of wood waste for convert it in biochar by the application of high temperatures and pressures in a reaction time that do not exceed 10 hours. One of the main applications of the HTC biochar is as pellets. In this research durability against fungal decay and dimensional stability associated with relative humidity changes of HTC pellets were analyzed and evaluated. A comparison of these properties between HTC pellets and wooden EN+ pellets has been carried out. HTC pellets are significantly more durable against fungal attack, more dimensionally stable against relative humidity changes and denser than wood pellets, which confers better properties for logistics processes like storage and transport.
This paper aims to find a simple testing and assessment model applicable to lignocellulose-based pellets, for the purpose of making the appropriate selection from the market. It is analysed the main tests of pellets, as density, caloric value and shear strength, for three different types of pellets bought from the competitive market. Afterwards is detailed the method of operation for the shear strength due to its not so frequent use. Finally, based on the tested values and limits required by the existing standards, it is determined a simple method for assessing for pellets, pointing out the closeness of each tested value to the standard limits.
WOOD RESEARCH Volume 61, Number 3
Wood ultrasound drying is an innovation method, it can reduce overall drying time, increase the mass transfer rate, and increase the effective water diffusivity. In this paper, poplar was taken as experimental material. The drying process was carried out under the conditions that the drying medium temperature is 60°C, the absolute pressure is 0.02 MPa, the ultrasound power is 100 W and the ultrasound frequency is 20 kHz. The moisture content distribution and water diffusion coefficient were studied, and the model among wood moisture content variation, drying time and water diffusion coefficient was established. Results indicated that the moisture gradient increases along with the increase of drying time during the drying process, free water and bound water are dried simultaneously when wood moisture content is above the fiber saturation point; Wood moisture decreased linearly when moisture is above the fiber saturation point, while the descending rate decreases when the moisture content is below the fiber saturation point. The water diffusion coefficient decreases along with the increase of drying time and increases exponentially along with the increase of moisture content. The moisture diffusion coefficient is 2.89×10-4 at the beginning stage, it is 3.02×10-6 when the moisture content is at the fiber…
This study characterizes the basic biometric traits of the black locust growing in urban conditions of the city of Wrocław (south-western Poland) and sets out the relationship between annual tree ring widths and air temperature, air humidity and precipitation. Materials consisted of 54 wooden discs taken from felled straight-trunked trees at four sampling sites at a height of 1.3 m from the ground in the area of a defunct garden established at the turn of the 20th century. Meteorological indicators were calculated based on daily data obtained from the Wroclaw meteorological station, part of the national atmospheric monitoring network. Tree ring widths were determined separately in heartwood and sapwood using LINTABTM 6 and TSAP-Win software, to an accuracy of 0.01 mm. Just over 85 % of the analyzed trees were at least 61 years old. In the heartwood layer the average tree ring width of 2.44 mm was about 1.08 mm wider than in the sapwood layer. Results confirmed the significant effect of warm winter and cool July on the ring widths of the black locust. The greatest demand for water was statistically proven in the period June to August in the year preceding the formation of the tree ring,…
The main goal of this study was to determine fire resistance properties of wood treated with pomegranate extract and mordant mixes. According to that wood materials Scotch pine (Pinus sylvestris L.), Oriental beech (Fagus orientalis Lipsky) were chosen. Aluminum sulphate (KAl2(SO4)3.18H2O) copper sulphate (CuSO2.5H2O) and vinegar were used as mordant agent and a synthetic dye was used for comparison. Ultrasonic assisted method were used for extractionthe plant dyestuff from pomegranate skin (Punica granatum) and then applied to wood blocks by immersion (classic) and immersion ultrasonic assisted methods. The combustion test was realized according to ASTM-E 69-02 (2002) standard. The mass losses release of gasses (CO, O2) and the temperature differences of samples were detected for each 30 seconds during combustion. The results showed that the aluminum sulphate mixes were showed the best results on all tests. Unfortunately test performances are not enough to retard the fire effect on the wood materials. Eco-friendly natural colorant might be developed to use them as fire retardant.
The main goal of maintenance management is to accurately predict the performance of structures over their life-cycle in order to develop the optimal maintenance programs. The aim of this paper is to present one of the prediction models of aging of timber concrete composite structures which will capture the true nature of deterioration. We focus on modelling the deterioration of deflection in the mid-span of the timber-concrete composite beam under a service load. Due to the nature of this composite beam, relative mid-span deflection is generally uncertain and non-decreasing over time, so it could be regarded as a gamma process. The progress of deterioration and estimate its service life will be presented.
Numerical simulation based on a non-linear material behaviour definition of concrete being a part of a coupled timber-concrete load-bearing system is presented in this paper. The main goal of a NL material modelling performed and introduced herein is to define the influence of concrete fragility over transverse loading distribution horizontally a locally loaded slab. The gained knowledge is consequently applied in a local fire exposure problem. Numerical simulations based on both linear elastic (LE) and non-linear (NL) material behaviour are compared with the results obtained from several real-size experiments and the effects of specific phenomena are discussed further. NL material definition of concrete is also termed as a “damaged material model” in certain references. This work is a continuation of the research performed at the Department of Civil Engineering, University of Coimbra, which’s result had been analysed and further published in paper (Dias et al. 2013) and doctoral thesis (Monteiro 2015).
Wood material is generally preferred due to its resilience against earthquakes, aesthetic properties, and its warmth as well as being natural. One of the major problems of employing this natural and breathable product is its ease of combustibility. Despite this adverse characteristic, its high resistance against burning and its ability to maintain its weight bearing characteristics until the very end does not lead to sudden collapses as is seen in steel and concrete systems. Treating wood with impregnating materials in order to improve its resistance against burning is an improved safety measure for the prevention of ignition. This study investigate seasonal effects on the ignition characteristics of chestnut wood samples impregnated using either Tanalith-E or Wolmanit-CB as detailed in ASTM–D 1413–76 and surface-treated using water-based or synthetic varnish as detailed in ASTM-D 3023- 88. The temperature of burning process was the highest in the investigated samples, in those impregnated with Wolmanit-CB and those that were treated with water-based varnish. The results of the study indicated that weight loss was lower during winter (84.59 %), for samples that were impregnated using Wolmanit-CB (84.46 %) and in those that were treated with water-based varnish (84.18 %). On the other hand, the O2…
In researches there are contradictory conclusions about interconnection between macrostructural and acoustic characteristics of sounding timber. Unfortunately, there are only a few works of such kind and all of them are of sporadic nature, which give evidence of necessity to continue such researches both at the level of macrostructure and microstructure. The aim of the research is to reveal the peculiarities of sounding timber microstructure, thanks to which it combines two incompatible, at first sight, parameters: High modulus of elasticity (rigidity) and low density. As a result, sounding timber differs from ordinary one in its unique acoustic characteristics, especially in delicacy and timber of sounding. The research results were obtained through applying an electronic scanning microscope to 360 constant and temporary specimens. For this purpose, 800 timber cuts were made in transversal, radial and tangential directions of a tree stem. Besides, macerated material was used to define early and late tracheids length. In the course of the experiment the increment layers width, the number of tracheids in a radial row of early wood, the number of tracheids in a radial row of late wood, the radial and tangential diameters of early and late tracheids, the thickness of tracheids radial and…
To improve the flame retardance and antibacterial properties of wooden wallpaper, a composite modifying agent, containing primarily a phosphorus-nitrogen flame retardant (APP/PER/GP), synergistic and smoke suppression agent (OMMT) and silver loaded with nano TiO2 (Ag-TiO2), was prepared and applied to the wooden wallpaper using an ultrasonic immersion method. The combustion performance (including smoke suppression performance), antibacterial activity and the surface micrographs of the flame retardant/antibacterial wooden wallpaper (FRAW) were investigated and characterized using a cone calorimeter test (CCT), antibacterial rate (AT) and inhibition zone, atomic force microscope (AFM), field emission scanning electron microscope (FE-SEM) and energy dispersive spectrometer (EDS). Furthermore, CIE1976 (L* a* b*) color system was used to estimate the surface color change of the FRAW. It was found that the composite modifier distributed on the surface of FRAW with a micrometer, improved the flame retardance of FRAW, but also improved its antibacterial property. In addition, the smoke release behavior of the FRAW indicated that OMMT had good smoke suppression properties. Furthermore, the result of color difference test showed that the flame retardant and antibacterial treatment had little effect on the decorative appeal of the wooden wallpaper.
The system wood chipping in disc chipper Carthage-Norman in industrial plant in Poland was investigation, because there were problems with obtaining homogeneous length of chips. The knife height, wedge angle of knife, clearance angle (pull-in angle), spout angle, average log diameter and construction parameters of chipper have been measured. These parameters were used to determine analytical of average length of chips in the studied disc chipper - Carthage-Norman. Model in Matlab/Simulink for the computation of the chip theoretical length was used. Also carried out the calculation and simulation to determine the maximum and minimum length of chips that can theoretically occur while cutting wood in the studied chipper. Finally, the theoretical lengths of wood chips and the actual lengths produced during cutting were compared.
This study describes the effect of heat treatment on the some of the physical and mechanical properties of beech (Fagus orientalis Lipsky) wood at different temperatures and times. Samples of beech wood were heat-treated at 150, 175, and 200°C for 1, 3 and 5 h. The mechanical properties of the heat-treated and untreated samples were determined by bending tests, modulus of elasticity in bending, compression strength parallel to grain, and Brinell hardness. Physical properties were determined by weight loss, density, and volumetric swelling tests. The results showed that the heat treatment increased the weight loss, density loss and dimensional stabilization. In addition, an increase was observed for compression strength parallel to grain (except for at 200°C for 5 h), while a small increase was determined in the bending strength, modulus of elasticity in bending, hardness values of heat-treated wood samples at 150°C for 1 and 3 h. However, the heat treatment at higher temperature and duration clearly decreased bending strength, modulus of elasticity in bending,and hardness.
The article presents the results of research on changes in humidity of wood chips intended for the of wood-polymer composites (WPC) manufacture. In the studies were used wood chips of various origin (coniferous and deciduous wood) and the various forms (from dust-meal, through small chips on big chips). Measured moisture content of chips during drying in the dryer and after that, during the natural return to hygroscopic equilibrium with the atmosphere of the storage space. After drying, the samples were stored in open and closed containers.
Technical parameters in different steps of birch (Betula alnoides Buch.-Ham. ex D. Don) veneered decorative straw particleboards producing process including moisture content adjustment, sanding, hot-pressing and conversation to improve the surface warp was discussed in this study. The results showed that it took at least 24 h to adjust the stable moisture content between 8 and 10 % in environment of 30ºC and 40 % relative humidity (RH). Surface warp decreased with the increase of sand thickness till 0.8 mm which indicated the complete remove of hardening layer. Modified “PVAc+GB-3+flour” bonded boards had better surface bonding strength than PVAc with a best hot-pressing parameter: unit pressure 0.7 MPa, temperature 90ºC and hot pressing time 180 s. In addition, surface warp of hot-pressed veneer decorative straw particleboards stabled when conserved for 24 h sealed with plastic films. Enterprise large scale production according to this technical process proved to decrease the surface warp from 1.05±0.3 % (normal process with sanding thickness of 0.3 mm) to 0.84±0.2 %.
Research was focused on evaluation of a circular saw blade tooth spacing on maximum equivalent noise level LAeq in the process of cross cutting wood. There were used circular saw blades with uniform tooth spacing and a full body and non-uniform tooth spacing with dilatation gaps. The measurements were done on the measuring device which was designed at the Department of Environmental and Forest Technology where it has been modernised. For research, testing samples of three wood species i.e. spruce (Picea abies), pine (Pinus sylvestris) and beech (Fagus sylvatica) were used. In the cutting process, two feeding speeds were set up with the same revolutions of circular saw blades and for more precise statistical significance; every measurement was repeated several times. At the research, there was found out that the circular saw blade with uniform tooth spacing has lower equivalent noise level at smaller feeding speed and cutting soft wood species. The circular saw blade with non-uniform tooth spacing has lower equivalent noise level at higher feeding speed.
One possible way to use waste materials in the wood industry (chip, dust, smaller pieces) is to transform them into pellets. Pellet making requires, however, additional energy which should be as low as possible. Present work examines the possible origins of binding forces and experimental evidences show that also the presence of water on particle surfaces plays a definite role. It also turned out that the water potential curve of timber materials can successfully be used to estimate the relation of compaction pressure to the water tension of the material.
Great interest is attracted lately in the utilization of Black locust (Robinia pseudoacacia L.) timber large quantities that are expected to be harvested and enter the market next years, since this species was included in the proposed and financed species for cultivation by the European Union. This study was carried out to evaluate the strength of the two most frequent joints in the upholstered furniture frames, constructed with black locust, using also beech wood (Fagus sylvatica L.) for comparative reason. In the specific research, the joints of mortise and tenon and double dowel were selected to be used and were constructed both in corner and middle joints, using two adhesives (PVAc and PUR). Bending moment capacity of the joint specimens was investigated, as well as the coefficient of elasticity of each joint.
This article deals with optical measuring of sawdust dimensions by IP camera. Optical methods of sawdust dimensions measurement are relatively extended and offer more information about measurement sample than other methods. By descripted method it is possible to specify dimensions, perimeter, area of each particle, as well as eccentricity, centroid position, segmentation of edges and other. Using IP cameras to obtain the image with samples it is possible to measure sawdust, e. g. at the manufacturing, and to evaluate the results at another location (laboratory). This eliminates need to carry a measuring system to measuring location. Compared to other methods (e. g. sieve method), descripted method is repeatable because the samples are not mechanical damaged and crumbed by jolting through the sieves.
WOOD RESEARCH Volume 61, Number 4
This study deals with the impact of silicon-based chemicals on selected physical and mechanical properties of wood. Wood of European beech and Scots pine was the testing material used for impregnation using water glass and commercial product Lukofob EVO 50. The impact of the treatment on dimensional stability, bending strength and modulus of elasticity was tested. Wood density was also evaluated. Although the modification using silicon-based staffs resulted in a statistically significant decrease in swelling for both of the tested species, the positive effect of the treatment was accompanied by a decrease in the strength and stiffness of wood. Water glass had a stronger effect on the tested properties from the chemicals we used in our research.
The decrease is supposed of the coniferous assortments supply due to running changes of tree species composition in the Czech forests as well as due to the environmental changes in the next decades. The Norway spruce (Picea abies /L./ Karst.) is the most endangered species. The year timber supply decrease of this species is supposed in an extent of 0.9 mil.m3 in the next two decades (2013 – 2032) and more than 1 mil. m3 for all conifers. Cultivation of Douglas-fir (Pseudotsuga menziesii /Mirb./ Franco) can substitute N. spruce on specific sites and so eliminate partially the timber supply decline in the future. The cultivation of Douglas-fir could lead to increase of the plantation area from 5,800 ha (today) to the extent of 49,616 – 163,713 ha respecting legislative restrictions and recommendations of general management plans. This can represent increased timber increment of 300,000 – 650,000 m3 per year and substantially mitigate the coniferous timber supply fall in the next decades.
The awareness of the need to protect wooden members dates back to the Middle Ages when the most common material for the protection of wood was oxblood. At present, there is a huge variety of biocidal chemical agents for wood protection available (such as Lignofix, Bochemit). Nanotextiles represent a novel method of enhanced biocidal protection of historic wood which has been intensively verified at the Faculty of Civil Engineering, CTU in Prague within the NAKI DG16P02M055 research. The paper will present partial results of experimental research into the effects of selected nanotextiles on the surface of historic wood applied for the purpose of biocidal protection. The research included the verification of the efficiency of nanotextiles without dopants and with dopants of Ag and TiO2 nanoparticles. Surprisingly, a higher biocidal efficiency of nanotextiles without dopants was reached than in the case of nanotextiles with dopants.
Currently, the trend of using untreated wood elements in the exterior is becoming more progressive. The rainwater nevertheless needs to be recognized as an important factor increasing photo-degradation of wood and causing other damages as splits, cracks and deformations. The aim of this work is to determine the influence of initial stages of weathering on wetting properties of wood surfaces evaluated by the contact angle measurements using goniometer Krüss DSA 30E. Nine wood species were tested during 12 months of weathering: spruce, larch, pine, Douglas fir, oak, black locust, maple, alder and poplar. The lower decrease of the contact angle of water drop was observed on maple, alder and black locust surfaces, which predicts higher durability and slower degradation during weathering. On the contrary, the higher decrease of contact angle and higher hydrophilicity of wood surfaces was observed on all softwoods and oak and poplar as well.
The article describes behaviour of the structure of a prefabricated winder wooden staircase with central stringer on the material basis of Scots pine (Pinus sylvestris L.). It focuses on static behaviour of this structure. An analysis was performed with the use of 3D numerical modelling with the finite element method using ANSYS calculation system. The numerical analysis with an orthotropic material model and Hoffman and Tsai-Wu interactive failure criteria showed critical points of this type of analysed staircase. Subsequently, selected critical points were experimentally tested for static loading on models of wooden fragments of the staircase in the scale of 1:1. Experimental tests and numerical analyses pointed out the importanceof a suitable choice of a material model of wood and the necessity to pay particular attention to designing of these points. The results and conclusions could be helpful for designing of a prefabricated winder wooden staircase with the central stringer.
The article deals with research of joints with glued-in threaded rods. The introduction provides a brief presentation of the issue. The first part focuses on axially loaded glued-in threaded rods. The second part explains the behaviour of joints with glued-in rods loaded by bending moment. Theoretical analysis was performed on models based on the finite element method. Verification of theoretical results was realized by practical experiments. Tensile tests were carried out on timber blocks with glued-in bars to verify the depth of affixing. Furthermore, the resistance in bending was confirmed on actual beams with glued-in bars in the middle of the span. Results and the follow-up work are summarized in the conclusion.
The content of this article is to analyse destructive testing results of longitudinal solid wood joints of structural size beams with internal and external glued wood-based panels (plywood) stressed in bending, which was mostly focused on simulating the effect of the glued line thickness (1 and 3 mm) and the influence of contact surfaces of longitudinally connected elements when bending loads. The aim of this article is to compare the carrying capacity and the joint real behaviour under load with values obtained using numerical modelling and calculation according to valid standards.
The primary aim of the paper is to characterize the emissions of volatile organic compounds (VOC) in the indoor air of wood-based buildings in the Krkonoše Mts. region in relation to season, age of the building, air moisture content and engineering composition of building materials. It aims to identify the impact of important factors on the amount and content of VOC emitted into indoor air. The experimental part focuses on the assessment of influence of applied wood-based materials in the wood-based buildings on the quantity and quality of VOC emissions in indoor air. The second aim is to determine the impact of age of a building and the time of VOC measuring on the amount and content of emitted VOC, particularly on the amount of emitted terpenes and aldehydes. VOC emissions were analysed by gas chromatograph Agilent GC 6890 N with a mass spectrometer with cryofocusation, thermal desorption and library of spectra NIS 05.
The article analyses the air leakage rate in 203 newly constructed low-energy and passive wood-based residential buildings in the Czech Republic. The most frequent air leakage points were analysed in the buildings measured, and the development of the air leakage rate in the period monitored (2006-2014) was evaluated. A significant decrease in air leakage rate values was found out in low-energy buildings, while the results for passive buildings were more or less steady within the period in question. Further, airtightness of envelopes of low-energy buildings not equipped with a mechanical ventilation system with heat recovery reached, in some cases, values indicating that recommended values of the overall air leakage required by hygienic regulations are not ensured.
The thesis focuses on the matter of thermal bridges in case of wooden panel structures, both in case of low-energy and passive structure-standard. Thermography was used for localization of critical areas of structures – details of corner joints of external walls and ceiling connections. The values subject to comparison are the linear coefficient of heat penetration from the exterior and the lowest interior surface temperature. This results in the overall comparison of both the structures as well as elimination of the excessive heat flow, whereas the difference in detail of corner joints of external walls is 0.03 W.(m.K)-1 for both, and the difference in detail of the ceiling connections equals 0.07 and 0.08 W.(m.K)-1 respectively. The difference in the lowest interior surface temperature in detail of corner joints of external walls for both structures equals 1.34 and 2.99°C respectively, and in the detail of the ceiling connections the difference is 2.45°C.
This contribution focuses on the verification of temperature and moisture content conditions inside perimeter walls of timber buildings as regards the temperature and humidity requirements in buildings intended for permanent residence. We assessed: a simple perimeter wall of solid timber, a wall of glued BSH profiles, a wall of an existing log building with additional thermal insulation in two options, and a sandwich log wall with a layer of embedded insulation. This study contrasts theoretical calculations with the values measured in a real buildings. The effect of the humidity changes on the strength and stability of dowelled joints is analysed.
The article discusses the changes in diffusion properties of wood and wood-based materials. These changes are caused by excessive moisture content within the materials and the consequent possible attack by wood-destroying pests. Wood-destroying pests in this case are represented by microscopic filamentous fungi (i.e. mould), which slightly changes and deteriorates both, the characteristics of wood and wood-based materials, and the environment humans live in. This paper discusses the theory and application of microwave radiation and the experimental optimization of radiation to sterilize these biotic factors. Furthermore, the article describes the experiments conducted at the Faculty of Civil Engineering, demonstrating the results of sterilization process with regards microscopic fungi that occur in building materials. By analysing the results of the research, the optimum intensity of microwave emitters and necessary lengths of irradiation times were determined.
In general, building constructions containing wood elements are moisture sensitive. To increase the knowledge about their hygrothermal performance accompanied with assessments of risk of mold growth and other degradation mechanisms a set of analytical methods is typically used: standard calculation or more advanced mathematical models, laboratory measurements and field observations. Nevertheless, in some cases such approach seems not to be sufficient. Full size testing under controlled and long-time stable boundary conditions is needed in order to get more complex picture about the real performance and risks. In the first part, the paper informs about hygrothermal problems and mold growth modelling. The key part of the paper deals with methodology and technique available at University Centre for Energy Efficient Buildings: Full size façade openings for placing different assemblies of building envelopes with wood elements and facility with crawl-space type foundations. Furthermore, laboratory experiments and measurements together with in-situ monitoring as example are presented. The paper discusses combinations of advanced modelling used for design of experiments on one hand with expected results from full size controlled testing on the other hand. Classification of mold growth risk can represent an efficient way of expression of overall quality in this respect. First results are…
The paper describes experimental research in the real behaviour of connections and its application to the design and realization of new types of timber structures. According to the connection type, primarily dowelled joints with slotted-in steel plates made from solid and glulam timber have been examined. A vital factor in designing joints of timber structures is respecting wood properties related to its changes in humidity. It is namely the case of strength changes as well as volume changes in particular directions. The experimental tests have been used to evaluate the influence of material strength, diameter and dowel number on the load-bearing capacity of joints. Substantial strengthening of joint’s load-bearing capacity can be attained by eliminating transverse tensile stresses in the region of dowels. Thus the conclusions derived from the experimental research and from the real behaviour have been implemented by the authors to develop new types of timber structures.
The article describes the thermal - technical point of four wooden constructions in the passive standard, when one of the constructions was tested in an accredited laboratory 1007.4 thermal - technical diagnostics. The sample was made according to the laboratory´s requirement 1700 x 1700 mm and tested according to the test harmonized standard ČSN EN ISO 8990: 1994 Thermal insulation - Determination of thermal transmission properties in the steady state temperature - calibration and guarded hot box. The object of the tests was to declare heat thermal transmittance value - U value based on the measured surface temperatures (θsi) and energy consumption. Thermal resistance and thermal transmittance were empirically calculated according to the measured and standard values in accordance of the CSN 73 0540: 2011. Thermal protection of buildings. The other three structures will be structurally modified to reflect this normative value Upas 20 = 0.12 - 0.18 (W.m-2 . K-1) and ensure their cost optimization.
WOOD RESEARCH Volume 61, Number 5
The chemical compositions and structural characterizations of bamboo samples with three pretreatments using sand bath to heat were comparatively studied with Fourier infrared spectrum (FTIR). The results showed that the holocellulose and cellulose yields increased significantly and the dilute alkali (NaOH) pretreatment performed better lignin removal rate than that of dilute acid (H2SO4) and glycerin pretreatments.Furthermore, when the same solutions were used, the compositional changes were more remarkable at 135 than at 117°C, and the similar degradation of hemicelluloses was observed for the different pretreatments. With sodium hydroxide at 135°C, compared to un-treated bamboo, cellulose increased by 14.21 % and hemicellulose decreased to 13.98 %, counting the removal of lignin to 20.29 %. In which, the bamboo expressed the betterdelignification with sand bath and higher temperature and combinations with other methods of glycerin pretreatment should be evaluated in the future work.
The current study about physical properties of wood of Quercus robur L., Q. petraea (Matt.) Liebl., and Q. pyrenaica Willd. in Galicia (northwest of Spain) was based on the determination of proportion of sapwood, heartwood, infradensity, and porosity to understand and estimate the variation of these characteristics and/or properties in the Galician oaks. For this, it was necessary to fell several trees within the study area. In total, 45 trees were chosen in 15 different stands of provinces of Lugo and Ourense, i.e., we have obtained 45 wood slices of Quercus at 60 cm tall on the trunk of the tree, and 194 wood samples with a parallelepiped shape and dimensions of 2×2×4 cm ± 1 mm. The infradensity characterization reveals that oak wood from Galicia has a greater infradensity than French oaks, and Quercus pyrenaica has a higher infradensity than Q. robur and Q. petraea. There is a strong variation of the same based on the geographic origin, but there is almost no variation inside a plot. The global objective was to realize a detailed description on the physical properties of wood of these species for its possible use in industry cooperage. For this, the objective of this initial…
The effect of water prehydrolysis conditions, which was used as the first stage of wheat straw pretreatment, on the composition of filtrates was analysed. Many of the substances that are present in the prehydrolysis filtrates are broadly used and thus they contribute to improvements in the efficiency of bioethanol production. Prehydrolysis was carried out at temperatures of 140, 160 and 180°C and times of 30, 60 and 120 min. Xylose and its oligomers were the most represented in prehydrolysis filtrates, their yields increased up to 12.1 % with increasing weight of wheat straw removed up to 28.6 %. Besides xylose and glucose, acetic acid, formic acid and the phenolic compounds were also present in the prehydrolysis filtrates. At 160 and 180°C, levulinic acid and furfural and hydroxymethylfurfural, respectively, were also present. The solid fractions of wheat straw were subjected to steam explosion under the same conditions at 200°C for 2 min. Two-stage pretreated wheat straw was subsequently enzymatically hydrolysed. The conditions of water prehydrolysis combined with steam explosion pretreatment had a significant effect on the results of enzymatic hydrolysis of wheat straw. The conversion of cellulose increased with increasing prehydrolysis temperature and time from 64.8 to 91.7 %. Similar results…
The demand for partially harmless dyes produced from natural sources as an alternative to synthetic dyes has been increasing. Natural dyes environment and they are attractive materials contributing to the protection of natural balance and to the reduction of aesthetic concerns of people. Yet, for natural dyes to be long-lasting and cling to the surface, they need to be used with mordant substances. In the present study, the purpose is to determine the antifungal and antibacterial activities of natural dye obtained from pomegranate skin by means of ultrasonic. Plant extract obtained through ultrasonic method was applied to oriental beech (Fagus orientalis L.) and yellow pine (Pinus sylvestris L.) wooden materials by means of dipping and ultrasonic-assisted immersion. For the analysis of the results, data obtained from the natural dye were compared with those obtained from the synthetic dye. The findings of the analysis revealed that the most effective results in terms of antifungal activities were obtained from the solutions applied to yellow pine wood. For beech samples, the natural dye yielded better results when compared to the synthetic dye. Moreover, pomegranate skin solutions were found to prevent the spread of antibacterial activities. As a result, it was concluded that pomegranate…
Effects of dye concentration, dyeing temperature and time, volume ratio, and dyeing assistant and fixing agent, fixing time on the dye-uptake and K/S were investigated with orthogonal experiments. The major factors on dye-uptake and K/S were identified using visual and variance analysis. Dye-uptake and K/S were synthetically evaluated and optimally selected with fuzzy comprehensive evaluation. Results showed that dye concentration and temperature were significantly affected by all the seven factors during dyeing process on dye-uptake and K/S. The optimal parameters for the dye effect of maple veneer were: temperature 65.0ºC, dye concentration 3.0 %, dyeing assistant 40.0 g.L-1, dyeing time 3.0 hours, fixing agent 20.0 g.L-1, fixing time 10.0 minutes, volume ratio 1:20. Additionally, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) results indicated that reactive dyes were combined with maple fiber and diffused into the wood lumen and wood ray. X-ray diffraction (XRD) results indicated the intensive of crystallinity in the dyed wood was declined due to the dichlorotriazine reactive dye. Furthermore, thermogravimetric analysis (TGA) demonstrated that the residue of dyed veneer was higher than undyed, and the temperature at maximum degradation rate of dyed and undyed veneer was different.
Determination of carrying capacity of steel-timber joints with steel rods glued-in parallel to grain
The issue of behavior and deformation of joints of wooden structures is an integral part of the design of timber structures in its entirety. In this article the attention is therefore devoted to joints of timber structures. For testing there were selected joints with glued-in steel rods. These joints are currently, due to the frequent requirement for invisibility of joints in structures, at the forefront of interest. The content of this paper is therefore testing of these joints and determination of their carrying capacity and describing the type of deformation under load. These tests were carried out on a pressure machine EU100 in the laboratory of the Faculty of Civil Engineering VSB-TU Ostrava. The results of the laboratory tests have been statistically evaluated and accompanied by the graphical records of deformation response to loading. Comparison of test carrying capacity results with values determined from calculation according to the current applicable European standard for design of timber structures and numerical modeling are also presented.
This research investigates the prediction of modulus of elasticity (MOE) properties, which is the most important properties in many applications, of the oriented strand board (OSB) produced under different conditions (pressing time, pressing pressure, pressing temperature and adhesive ratios) by multiple regression, artificial neural network (ANN) and adaptive Neurofuzzy inference system (ANFIS). Software computing techniques are now being used instead of statistical methods. It was found that the constructed ANFIS exhibited a higher performance than multiple regression and ANN for predicting MOE.Software computing techniques are very useful for precision industrial applications and, also determining which method gives the highest accurate result.
This thesis deals with experimental verification of hot-air preservation efficiency on wooden members of structures against larvae of wood-destroying insects, particularly against larvae of longhorn beetle Hylotrupes bajulus L. The verification of hot-air efficiency on mortality of larvae was performed within the process of hot-air preservation of a room of a building in Čeladná, Czech Republic. Parameters of hot-air preservation met the specifications of standards according to which the process is controlled. The efficiency was monitored by means of the Acoustic Pack acoustic system which recorded acoustic emissions of larvae emitted during wood ingestion. To verify the acoustic system and hot-air preservation, the samples were subject to destruction analysis after the preservation. Using a Keyence VHX-S550E digital microscope, the analysis of changes in the structure of larvae before and after the process of preservation was performed. The results showed that designed parameters of hot-air preservation lead to the mortality of larvae.
This study presents the influence of retention reagents and multi-component retention systems on properties of pulp suspension which is used during toilet paper production. The following relationships were evaluated: influence of retention systems on rate of pulp suspension water drainage, values of specific cationic and anionic demand, Zeta potential of fibers, WRV values of fibers and water turbidity. The best results were achieved from applying three-component retention system which consisted of micro-milled bentonite Hydrocol OT, modified cationic polyethylenimin Polymín SK and cationic polyacrylamide Percol 830. The above mentioned three-component retention system resulted in increased rate of pulp suspension drainage by 43 %, improvement of water turbidity by 50 % and decrease of specific cationic demand by 33 %. The proposed retention system resulted in improved values of WRV pulp suspensions, which led to decrease of values by about 10 %. Influence of three-component retention system resulted only in minimal decrease of Zeta potential values for fibers.
Spoil heaps are negative urban landscape features resulting from intense human activities to acquire mineral resources. One very positive method for reclaiming spoil heaps is afforestation. This paper analyzes the quality of Black locust wood acquired from the reclaimed area of Varvažov, North Bohemian Basin, Czech Republic. The following characteristics were used as indicators of the quality of wood obtained from the given area: chip dimensions; ash content; bulk density; bark content; contents of C, H, N, and O; and contents of S, P, Ca, Mg, K, Fe, Zn, and Mn. Black locust biomass is suitable for energy purpose, although it contains an increased proportion of inorganic elements. The other properties, such content of C, H, N, and O, ash content as well as heating value, are in compliance with the standardized values. The Black locust chips can be categorized as Coarse-grained energetic wood chips with minimal dust particle content according to particle-size distribution analysis.
In this study, the surface quality of birch wood (Betula) test pieces planned with experimental planning tools (ET1, ET2) and influence of tool wear of quality of surface were examined. These tools were made by surfacing using a submerged arc welding (SAW) technique and a mixture of alloying elements (cromium, tungsten, fero-manganese, silicon carbide) spread on the surface under industrial flux. Surface roughness was measured along and across wood fibre. According to the results of experiments it is obviously that average roughness parameters along fibre is lower than across. Planning tool wear results revealed that 3200 m of cutting length is not significant for tools ET1 and ET2 wear. The same can be said about tool nose width change: For ET1 from 2.8 to 2.9 μm, and for ET2 from 2 to 3.4 μm – effect of negligible changes of tool edge geometry on planned surface quality is low. Feed of planning tool played more significant role – twice higher feed per insert (ET1 – 1.00 mm, ET2 – 0.5 mm) showed lower surface quality after planning. To reach necessary wood surface quality, lower feed rate and suggested experimental planning tool ET2 with higher wear resistance than commercial tool is…
The objective of this study was to evaluate the effects of screw diameter, pilot hole diameter, screw type and loading rate on the withdrawal resistance of some screws in reconstituted bamboo lumber (RBL) and comparison of screw withdrawal resistance in RBL with MDF and Particleboard. Results indicate that there were no significant differences among withdrawal resistance with screw diameter, screw type and loading rate. Significant differences were found between withdrawal resistance with pilot hole diameter. Screw withdrawal resistance decreased with increasing pilot hole diameter. Suggested size of pilot hole is 60-85 % of the nominal screw diameter. The withdrawal resistances in the face and edge of RBL are greater than the end direction. This reveled RBL is anisotropic. Face and edge withdrawal resistances of screws in RBL were higher as compared with those of MDF and particleboard. This indicates that withdrawal resistance of RBL meets the requirements of furniture structure design.
The results of testing of chips extraction system efficiency during CNC milling of particleboards were presented in this paper. Experimental machining was performed using the 3-axis CNC router Weeke Venture 108M and a standard diamond tipped, newly sharpened shank-type router bit. As a material the market size (2200×1250×18 mm) laminated particleboards with density of 649 kg.m-3 were used. The efficiency of chips extracion system of the CNC machine depends on the mode of milling. For pocketing nearly 100 % of chips were removed succesfullywhile for through-milling it was only 87 %. The extraction system worked with very high effieiency regarding chips smaller than 0.1 mm. The chips extraction efficiency decreases for larger and havier chips.
In the current European standards for the design of timber structures, the issue of timberto-timber joint type is addressed only to squared timber, which makes the pinpointing of the round timber bolted joints carrying capacity near-unfeasible due to the insufficient support in the current standards. There have been made series of tests of round timber joints in different inclinations tensile load to the grainand also the reference tests of squared timber joints to compare the behaviour of this type of joints. Mechanical behaviour of round and squared timber bolted joints were tested in the laboratory of the Faculty of Civil Engineering in Ostrava.This paper presents results of static tests in tension at an angle of 0, 90 and 60° to the grain of squared and round timber bolted joints. Carrying capacity was determined according to the applicable standards and theories of fracture mechanics. Round timber joints were also numerically simulated. The test results of numerical models were then compared with the results of laboratory tests and theoretical calculations.
In order to improve people's living quality and ameliorate their living environment, making the full use of the environmental characteristics of wood materials in the building and interior decoration become more and more important. In this paper, the development and application of eye tracking technology is summarized, and the development trend of eye movement research in the field of wood environment is reviewed. Through an eye tracking experiment research on indoor wood decoration space to explore if different specialty, the sex, the wooden interior proportion factor have significant effect on people's judgment on the picture preference or not. Make exploration of people for different wood interior decoration environment preference and visual cognitive style, providing new ideas and methods for room decoration design. On the other side, through the study of the eye movement to explore the wood interior decoration environment has an objective and effective and scientific significance.
Comparative research was conducted on shear strength parallel to grain of heartwood of Scots pine (Pinus sylvestris L.) from the 16-18th century from Central Poland and of modern wood. Tests were performed on 150 samples of aged wood from 13 construction elements of 4 historic buildings and on 100 samples from 10 modern constructional elements. Aged wood revealed a better technical quality. The difference of average shear strength parallel to grain values equaled 0.09 MPa and the translation of correlation line was about 0.35 MPa in favour of aged wood.
WOOD RESEARCH Volume 61, Number 6
Microfibrillated cellulose (MFC) films with a layered structure and controlled thickness were successfully prepared, from bamboo processing resides as the source material, using ultrasonication followed by simple vacuum filtration. The effects of thickness and moisture content on the mechanical properties of the films were then investigated. It was shown that tensile stress and elongation at break were notably affected by the thickness of the MFC film, where the tensile stress and elongation at break of the film increased from 124 to 179 MPa and 0.9 to 5.5 %, respectively, as film thickness increased from 7.4 to 205.4 μm. However, no notable effect of thickness was observed on the Young’s modulus (~10.8 GPa). It was also found that moisture content has a significant impact on the tensile properties of MFC films, in lowering the Young’s modulus from 12 to 2 GPa and tensile stress from 180 to 90 MPa, and increasing the elongation at break from 4.2 to 17.5 %, as moisture content increased from 3 to 60 %. This is due to the effect of water in softening MFC films, resulting in a reduction in strength and increase in flexibility.
This paper presents a simple approach for the derivation of effective properties of wood while accounting for its inherent anisotropy. These properties are found by combining the results of structural indentation using the Pilodyn 6J testing device and analytical homogenization in the framework of an inverse approach. This approach provides first a rough estimate of a microfibril angle and subsequently yields the predictions of the effective properties of wood. While applicable to any kind of wood we adopted the proposed methodology to spruce as a typical representative of soft wood. This allows us to exploit the presented results directly in the analysis of glued laminated timber beams made of spruce wood which is a principal goal of the present research.
The quality of lumber drying is traditionally evaluated after the process. This paper proposes the algorithm of quality assessment of low-temperature convection lumber drying in accordance with the target values of the average final moisture content and its dispersion in the stack. The stochastic model of the process with random initial and boundary conditions, which allows calculating the dispersion of the final moisture content (MC) was proposed. To describe the kinetics of the wood drying process in the low-temperature chamber in view of the thermodynamic characteristics, 34 processes of drying of oak and pine lumber with the thickness of 30, 40 and 50 mm were made at the wood-processing enterprises in Ukraine. The theoretical equations of lumber low-temperature drying and the values of the coefficients that characterize the influence of material thickness, temperature and moisture fields’ distribution in the material during the drying process were obtained. The check of the proposed models on the uniformity of the average values and dispersion of the current moisture content showed a slight difference between the experimental and calculated values. These models allow predicting the quality of the low-temperature drying on the spread of target moisture content, which enables selection of rational drying schedules.
Selected physical and mechanical properties of high density polyethylene (HDPE) composites filled with various mixtures of wood flour and tinder fungus (Fomes fomentarius) were investigated. For this aim, different mixtures of tinder fungus flour and wood flour (0/40, 10/30, 20/20, and 30/10, and 40/0) (by weight) were compounded with HDPE with a coupling agent (maleic anhydride grafted polyethylene (MAPE) in a twin screw co-rotating extruder. The test specimens were produced by injection moulding machine. The thickness swelling and water absorption of the HDPE/wood composites significantly decreased with increasing content of the tinder fungus flour. The mechanical properties of the composites were negatively affected by increasing amount of tinder fungus flour but there were no significant differences up to 30 wt % tinder fungus content, except for the tensile strength. The optimum physical and mechanical properties for the filled HDPE composites were found to be a 10/30/60/3 formulation of wood flour, tinder fungus, HDPE, and MAPE, respectively.
GradaTM is new plywood which contains the thermoplastic adhesive. There are so far two material versions 1000 and 2000 which have wide potential in production of wooden products with new perspective of manufacturing. This paper investigates possibilities of including GradaTM material and its versions in skateboard production. Bending strengths at the moderate heat up of this material are presented, specifically at 30, 40°C for both material versions. All increased temperatures are compared to the room temperature (20°C). Mechanical properties that were obtained from the test are modulus of elasticity, modulus of rapture, and stroke strain. The results show the undesirable level of changes present in both versions however version 1000 acts significantly better than 2000.
In this study, it was aimed to investigate surface hardness, gloss, and color changes of Scots pine treated with chemicals containing some copper compounds after six months weathering. Adolit KD-5 (AD KD-5), celcure AC-500 (CAC-500), and wolmanit CX-8 (WCX-8) were used as impregnation chemicals containing copper compounds. Scots pine wood specimens were treated with 2 % aqueous solution of chemicals according to ASTM D1413-07e1 (2007) standard. Results showed that while surface hardness and gloss values of untreated Scots pine wood specimens were decreased after weathering, they increased treated Scots pine wood specimens after weathering. The decrease in L* of untreated and treated wood indicates that the specimens became darker after weathering. While weathering caused less green and less yellow for untreated control specimen, it caused less red and less yellow for treated wood. Treated Scots pine wood specimens showed better color stability compared to untreated Scots pine after weathering. In terms of surface hardness, gloss, and color stability values CAC-500 treated Scots pine gave the best results after weathering.
At the coating were used two substrates, commercial base paper and base paper produced in pilot experimental paper machine. The printing quality varied at both base papers. The coating colours contain commercial silica and precipitated calcium carbonate pigments. As a binder was used polyvinyl alcohol and cationic starch combined with high-cationic polymer SMAI 1000. Colour gamut significantly improved when the inkjet ink contact angle decreased below 14° independently of the base paper. The order of coating colours effect on the base papers was similar. Application of silica pigment in the coating colour provided papers with the largest inkjet ink wetting, the best colour gamut area, print sharpness and smoothness. By using of polyvinyl alcohol, a high colour gamut area was reached but it resulted in a markedly low print sharpness in comparison with cationic starch. Coating of base paper produced in pilot experimental paper machine introduces papers with higher colour gamut and also print sharpness.
This study was conducted to explore the utilization of tomato stalk in the paper industry. Fiber morphology of the material was determined according to standard test methods and average fiber length was found to be 980 μm and the width of the fiber was 15 μm. As a result, slenderness ratio was resolved to be around 60. This was considered to be comparable fiber with the most of the hardwood species. Tomato stalks were cooked with soda and lime in a separate process. Screened pulp yield was determined to be 35-45 %. Soda pulp of tomato stalks showed good mechanical properties when temperature raised to 135ºC and low alkali concentration (10 %) and lime pulps showed properties as well as that soda pulp at 135ºC and high alkalinity ratio (30 %).
The aim of the work was to analyse the influence of Mg(OH)2 nanoparticle dosage on the deacidification process, especially in relation to paper permanence. Samples of model papers were characterised by SEM-EDX and XPS methods which proved effective neutralisation. The influence of the suspension concentration was evaluated on cellulose DP and on the optical properties after the paper thermal ageing process. Generally, the protective effect of deacidification increased along with an increased dosage of the magnesium hydroxide nanoparticles in artificially acidified paper samples and in papers covered with iron gall ink.
Critical strain energy release rate GC and stress intensity factor KC are both defined as fracture toughness, and they can be converted to one another through an equivalent elastic modulus for wood fracture. Whereas the equivalent elastic modulus for interlaminar fracture toughness of glued-laminated timber (glulam) is kept unknown. This paper briefly presented Modes I and II interlaminar fracture toughnesses of glulam, which were obtained from double cantilever beam (DCB) and three-point bending end-notched flexure (3ENF) tests using finite element method (FEM). On the basis of Hankinson-type formula and equivalent elastic modulus of wood fracture, this study developed two empirical expressions to calculate the equivalent elastic moduli for Modes I and II interlaminar fracture of glulam.
In this study, it was studied the effects of densification and then lamination processes on some mechanical properties of Lombardy poplar (Populus nigra L.), which is one of the low density tree species. Densification temperatures were 80, 100, 120 and 140ºC and ratios of densification were 15, 30 and 50 %. Furthermore, lamellas with a thickness of 4 mm cut from densified materials were laminated by bonding one on top of the other with urea formaldehyde (UF) and polyvinyl acetate (PVAc) adhesives. Bending, modulus of elasticity, compression and tensile tests were applied by preparing specimens from the pieces. According to test results, the most suitable temperature level was 120°C. As the ratio of densification was increased at this temperature level, increase were observed in the mechanical properties. Also, lamination provided significant increases in the mechanical values compared to laminated but undensified Lombardy poplar. Increases were observed in the mechanical properties reaching 444 % with application of densification and lamination processes.
Log computer tomography (CT) image reconstruction is the kernel of wood CT nondestructive testing (NDT) technology. In this paper, based on the logs physical properties and the X-rays propagation characteristics in solid, the X-ray wave equation inside logs is deduced. A weighted filtered back projection (FBP) algorithm for log CT image reconstruction is proposed. Four group of logs are chosen for simulations on the weighted FBP algorithm. In the twodimensional image reconstruction process, the capabilities between conventional FBP algorithm and weighted FBP algorithm are compared to verify the effectiveness of the algorithms for logs of different species. From both the image quality and data results, it can be clearly seen that the weighted FBP algorithm has good performance and advantages for image reconstruction process of log CT scan. The three-dimensional log image reconstruction is well completed, but has a big room for improvement.
Formation and presence of dust in the timber premises is part of the technology. Dust is generated as a byproduct based on the method of machining. The paper deals with granulometric analysis of selected samples of wood dust sessile oak (Quercus petraea Liebl.) and from deciduous multiple-pore wood there was chosen European beech (Fagus sylvatica L.) and alder (Alnus glutinosa L.) and the mixture taken directly from timber production of grinders SCM SANDYA 300RCS) for the purpose of selecting the percentages of the various fractions (0.032; 0.063; 00:08; 0.125; 0.250; 0.5; 1; 2 mm) of samples of wood dust. Wood dust samples were made using a hand orbital sander BOSCH PSS 200AC and sizing on the automatic mesh vibratory sieve machine Retsch AS 200 control. The most frequent percentages of dust particles (between 50-79 %) in all samples of wood dust there were fractions of 32 and less than 32 μm (bottom). The most abundant percentage creates conditions of the risk of inhaling and respirable components contained in the fraction over 32 μm and the potential of formation of a dust-air explosive mixture. Comparison of results granulomertic fractions contribution of wood sanding dust typically processed wood in the furniture industry…
Ultrasound has been used in prediction of bending properties for some important wood species grown in Turkey including Calabrian pine, Anatolian black pine, Cedar and Oriental Spruce. Sound velocities of small clear wood specimens were determined using EPOCH 650 ultrasonic flaw detector with 2.25 MHz contact longitudinal transducers at constant moisture content. Following non-destructive measurements, specimens were subjected to three point bending tests. The measured average sound velocities for species tested in L directions were ranged from 4510 to 5254 m∙s-1. Although spruce had the lowest density (425 kg∙m-3), it had the highest sound velocity. The predicted average dynamic modulus of elasticity (Edyn) values for the species tested varied from 10137 to 12856 N∙mm-2. The correlation coefficients between Edyn values and MOE values were higher than those between Edyn and MOR. Edyn values are higher than calculated MOE values. The correlation coefficient between predicted Edyn and calculated MOE values ranged from 0.81 to 0.89. The correlation coefficient between Edyn and MOR varied from 0.78 to 0.88 for the species tested. Results indicated that there was no certain relationship between the density and wave velocity except Calabrian pine which showed negative weak correlation. MOE is better indicator of MOR than Edyn…
This paper deals with research on the impact of composition on compression set of the PU foam mattresses. Three type of mattress composition, with sandwich structure and self-clamping joints, were used for research. The fourth type, which contained traditional glued joint, served as a reference. During static compression of mattresses, the properties of the individual layers have been recorded or calculated, such as Young’s modulus, shear modulus and coefficient of shear friction, which were necessary for the SolidWorks simulation of the permanent deformation. The results, as well as simulations of mattress compositions, have proven that the compression set is strictly dependent on the loading time. The highest permanent deformation was recorded for mattress type A and the lowest ones for mattress type B, which had permanent deformation almost identical to that of the composition with glued joints. The last two mattress types had permanent deformation 35 % greater. It is clear from the results that the properties of selfclamping joints in upholstery can equal those of conventional glued joints. Using self-clamping joints is more advantageous in that they exclude the negative effects of glues as well as the gluing process itself.
In this study, the semantic differential method was employed for investigating the tactile properties of bamboo qualitative material, such as bamboo integrated timber (vertical splicing plate), bamboo integrated timber (transverse splice plates), bamboo parallel strand lumber, whole bamboo unfolding plate (outer of bamboo), whole bamboo unfolding plate (remove outer of bamboo), bamboo plastic composite plate, while Liquidambar formosana and Abies fabri (Mast) were selected as contrast. Respondents rated the samples by descriptive words, such as natural, exclusive, eco-friendly, rough, inexpensive, reliable, warm, modern, snug, and solid. Moreover, statistical analysis was employed for analyzing the data. The results showed that material and tactile characteristics exhibit significant correlation. Principal component analysis yielded four attributes based on tactile perceptions. Summing up the main points of the experiment, the tactile properties of different bamboo qualitative material were obtained.
Physical and mechanical properties of flakeboards produced from radiata pine flakes under different hot-pressing conditions were investigated in this study. The flakeboard mats were hot-pressed at 2.8 MPa with two different temperatures (170 and 190°C) and three different durations (7, 10, and 15 min). At the 170°C of hot-pressing temperature, the highest bending strength was found in the flakeboards pressed for 7 min while the highest modulus of elasticity was found in the flakeboards pressed for 15 min. The highest internal bond strength was found to be 0.13 MPa for the flakeboards pressed at 190°C for 15 min. The thickness swelling and water absorption of flakeboards pressed at 190°C were lower than those of the flakeboards pressed at 170°C. The control of hot press temperature and duration appears an effective method to enhance serviceability of flakeboard.