WOOD RESEARCH Volume 62, Number 2, 2017
Simon Eichhorn, Sebastian Erfurt, Tamás Hofmann, Stefan Seegmüller, RÓBERT NÉMETH, and František Hapla

Determination of the phenolic extractive content in sweet chestnut (Castanea sativa Mill.) wood

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.

WOOD RESEARCH Volume 62, Number 2, 2017
Xiaoshuai Han, Qinqin Zhang, Ren Li, and Junwen Pu

Grafting organic-inorganic compound modifier onto wood cell walls for enhanced mechanical strength in wood composites

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).

WOOD RESEARCH Volume 62, Number 2, 2017
Marcin Klisz, Szymon Jastrzębowski, Tomasz Wojda, Joanna Ukalska, and Andrzej Noskowiak

Variability of Black locust hardness in relation to different measurement direction and location along the stem

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<0.001), as well as the significance of differences between study sites (p<0.001). For the radial and tangential directions, significance of differences between sites, stem parts and trees was confirmed (p<0.001; p=0.001; p=0.005, respectively). Preferred wood material should come from lower stem part, taking into account the highest hardiness in the longitudinal direction.

WOOD RESEARCH Volume 62, Number 2, 2017
Wei Sun, Xiaokai Mu, Qingchao Sun, and Weiqiang Huang

The impacts analysis of moisture content on mechanical properties of wormwood stem

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.

WOOD RESEARCH Volume 62, Number 2, 2017
Pavol Halachan, Marian Babiak, Dominik Spišiak, Anatoly N. Chubinsky, Alexander A. Tambi, and Kirill V. Chauzov

Physico-acoustic characteristics of spruce and larche wood

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.

WOOD RESEARCH Volume 62, Number 2, 2017
Martin Sviták and Daniel Ruman

Tensile-shear strength of layered wood reinforced by carbon materials

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.

WOOD RESEARCH Volume 62, Number 2, 2017
Hong Yun, Kaifu Li, Chuangshuang Hu, and Dengyun Tu

Adsorption and fixation of soluble fire retardancy in Populus russkii and Cunninghamia lanceolata

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).

WOOD RESEARCH Volume 62, Number 2, 2017
Beata Doczekalska, Agata Pawlicka, Krzysztof Kuśmierek, Andrzej Świątkowski, and Monika Bartkowiak

Adsorption of 4-chlorophenol from aqueous solution on activated carbons derived from hornbeam 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.

WOOD RESEARCH Volume 62, Number 2, 2017
Pažitný Andrej, Boháček Štefan, Peter Medo, Balberčák Jozef, Jiří Schwartz, Kuňa Vladimír, and VLADIMÍR IHNÁT

Possibilities of removing condensate from a heat recovery unit utilizable in paper industry

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 %.

WOOD RESEARCH Volume 62, Number 2, 2017
Miao Ye

Effect of wood modifiers on the physical properties of fast- growing poplar wood

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.

WOOD RESEARCH Volume 62, Number 2, 2017
Marija Đurković and Gradimir Danon

Comparison of measured and calculated values of cutting forces in oak wood peripheral milling

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.

WOOD RESEARCH Volume 62, Number 2, 2017
Krzysztof Szwajka and Tomasz Trzepieciński

An examination of the tool life and surface quality during drilling melamine faced chipboard

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.

WOOD RESEARCH Volume 62, Number 2, 2017
Aurel Lunguleasa and Cosmin Spirchez

Torrefaction of lamellar panels made of oak and spruce wood species

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.

WOOD RESEARCH Volume 62, Number 2, 2017
Aizat Ghani, Paiman Bawon, Zaidon Ashaari, Mohammad Waridwan Wahab, Lee Seng Hua, and Lum Wei Chen

Short note. Addition of propylamine as formaldehyde scavenger for urea formaldehyde-bonded particleboard

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.

WOOD RESEARCH Volume 62, Number 2, 2017
Szabolcs Koman, Sandor Feher, and Andrea Vityi

Short note. Physical and mechanical properties of Paulownia tomentosa wood planted in Hungaria

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.