WOOD RESEARCH Volume 61, Number 2, 2016
Oliver-Villanueva José-Vicente, García-Andújar Enrique, and Gascón-Garrido Patricia

Analysis of durability and dimensional stability of hydrothermal carbonized wooden pellets

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.

WOOD RESEARCH Volume 62, Number 6, 2017
Luis Fernando Pintor-Ibarra, Artemio Carrillo-Parra, Rafael Herrera-Bucio, Pablo López-Albarrán, and José G. Rutiaga-Quiñones

Physical and chemical properties of timber by-products from Pinus leiophylla, P. montezumae and P. pseudostrobus for a bioenergetics use

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. It is concluded then that the three pine species timber by-products present physic and chemical properties that make them suitable for the production of solid biofuel.

WOOD RESEARCH Volume 62, Number 5, 2017
Diaz-Maroto I.J., Vila-Lameiro P., and Tahir S.

Assessment of anatomical characteristics of wood – bark, sapwood and heartwood – in hardwoods species of Galician oaks by image processing: Relationship with age

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 two species. Therefore, our aim was to carry out a complete description of these parts of the wood, later, in upcoming work estimate their physical properties for use in cooperage industry.

WOOD RESEARCH Volume 62, Number 3, 2017
DONATA KRUTUL, Tomasz Zielenkiewicz, ANDRZEJ RADOMSKI, JANUSZ ZAWADZKI, ANDRZEJ ANTCZAK, MICHAŁ DROŻDŻEK, and Tomasz Makowski

Metals accumulation in scots pine (Pinus sylvestris L.) wood and bark affected with environmental pollution

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.

WOOD RESEARCH Volume 63, Number 5, 2018
DONATA KRUTUL, Tomasz Zielenkiewicz, JANUSZ ZAWADZKI, ANDRZEJ RADOMSKI, ANDRZEJ ANTCZAK, and MICHAŁ DROŻDŻEK

Influence of urban agglomeration environmental pollution on content of chosen metals in bark, roots and wood of norway maple (Acer platanoides L.)

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.

WOOD RESEARCH Volume 63, Number 3, 2018
Roman Fojtík and Kateřina Dědková

Analysis of diagnostic methods for detecting the presence of gloeophyllum spp

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.

WOOD RESEARCH Volume 63, Number 3, 2018
Li Hui and Zhongfeng Zhang

Cultural and creative product design based on biology characteristics of wood

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 2, 2018
Zhi Liu and Jinzhen Cao

Fabrication of superhydrophobic wood surface with a silica/silicone oil complex emulsion

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 1, 2018
Abdelraheem Ahmad, Abdelrahman Elserogy, Zeidoun Al-Muheisen, François Villeneuve, and Ahmad El-Oqlah

The conservation of a wooden nabataean coffin box from jordan – application of non-destructive ultrasonic technique

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.

WOOD RESEARCH Volume 63, Number 1, 2018
Nadir Ayrilmis, Ali Gürel, Mehmet Özdemir, and Tolga Kapti

Bond performance of formaldehyde-based resins synthesized with condensate generated during kiln-drying step of wood

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 condensate discarded to the ground water.

WOOD RESEARCH Volume 66, Number 4, 2021
TINGTING DENG, Shuang Ju, Minghua Wang, and MING LI

Study on propagation law of acoustic emission signals on anisotropic wood surface

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.

WOOD RESEARCH Volume 66, Number 4, 2021
Francisco Antonio Rocco Lahr, Vinicius Borges De Moura Aquino, Felipe Nascimento Arroyo, Herisson Ferreira dos Santos, Sergio Augusto Mello Silva, Anderson Renato Vobornik Wolenski, Carlos Maviael de Carvalho, João Paulo Boff Almeida, and André Luis Christoforo

Influence of stiffness related to the C40 strength class of the hardwood group established by the Brazilian standard in the design of timber structures

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.

WOOD RESEARCH Volume 64, Number 5, 2019
Ondřej Schönfelder, Aleš Zeidler, Vlastimil Borůvka, and Lukáš Bílek

Impact of silvicultural measures on the quality of scots pine wood Part II. Effect of site

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.

WOOD RESEARCH Volume 65, Number 6, 2020
Rudolf Petráš, Julian Mecko, Danica Krupová, and Pažitný Andrej

Aboveground biomass basic density of hardwoods tree species

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.

WOOD RESEARCH Volume 64, Number 4, 2019
Ondřej Schönfelder, Aleš Zeidler, Vlastimil Borůvka, and Lukáš Bílek

Impact of silvicultural measures on the quality of Scots pine wood. Part I. effect of regeneration method

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.

WOOD RESEARCH Volume 64, Number 4, 2019
Paweł Czarniak, Karol Szymanowski, Jacek Wilkowski, Jarosław Górski, and Fabrice Dagrain

Machinability characterization of solid wood with scratching and drilling techniques

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 of solid wood proved in described below experiments should result in higher reliability and usefulness of testing method.

WOOD RESEARCH Volume 64, Number 4, 2019
Li W. G. and Zhang Z. K.

The effect of micro-pits texture on the coefficient of friction between wood and cemented carbide under different wood moisture content

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.

WOOD RESEARCH Volume 65, Number 4, 2020
Roman Fojtík, Viktor Dubovský, Kateřina Kozlová, and Lenka Kubíncová

Prestress losses in spruce timber

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.

WOOD RESEARCH Volume 65, Number 3, 2020
Darius Albrektas, Milda Jucienė, Vaida Dobilaitė, and Raimondas Bliūdžius

The influence of thermal modification on the resistance to water impact properties and strength of wood used in outdoor conditions

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 the case of pine.

WOOD RESEARCH Volume 65, Number 3, 2020
Candan Kus Sahin, Mehmet Topay, and Ahmet Ali Var

A study on suitability of some wood species for landscape applications: Surface color, hardness and roughness changes at outdoor conditions

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.