Articles

WOOD RESEARCH Volume 63, Number 5, 2018
Minmin Li, Wenbo Xie, Xiwei Wang, Yu Cao, and Zheng Wang

Parameters optimization for ultrahigh-pressure pure water and abrasive water jet of Pterocarpus macarocarpus kurz processing

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 water jet cuts by choosing carefully the process parameters. The investigation of water jet cutting in this work throws some light on the configuration of process parameters while applying ultra high-pressure water jets, both with and without added abrasives, to the cutting of wood products of precious species.

WOOD RESEARCH Volume 63, Number 5, 2018
Miguel Ángel Cárdenas-Gutiérrez, Fabiola Eugenia Pedraza-Bucio, Pablo López-Albarrán, José G. Rutiaga-Quiñones, Fermin Correa-Méndez, Artemio Carrillo-Parra, and Rafael Herrera-Bucio

Chemical components of the branches of six hardwood species

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.

WOOD RESEARCH Volume 63, Number 5, 2018
Arkadiusz Tomczak, Karol Tomczak, Natalia Smarul, Krzysztof Rutkowski, Małgorzata Wenda, and Tomasz Jelonek

The gradient of wood moisture within-stem of sessile oak (Quercus petraea (matt.) Liebl.) in summer

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.

WOOD RESEARCH Volume 63, Number 5, 2018
N.N. Sibiya, M.J. Mochane, T.E. Motaung, L.Z. Linganiso, and S.P. Hlangothi

Morphology and properties of sugarcane bagasse cellulose- natural rubber composites

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.

WOOD RESEARCH Volume 63, Number 5, 2018
Xiaojun Yang, Lan Ma, Qi Zhao, Yihao Yu, Xiaolan Tang, and Daoyuan Tang

Enduring performance of self-tapping screw connection in wood members and WPC members

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.

WOOD RESEARCH Volume 63, Number 5, 2018
Mehmet Yeniocak and Suleyman Kahveci

Investigation leaching performance of wood materials coated with cotinus coggygria extracts and liquid glass (SiO2) mixture

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.

WOOD RESEARCH Volume 63, Number 5, 2018
Mingbin Liu, Keyu Ge, Youfu Sun, and Xiaolin Yang

Effect of constitution on sound insulation performance of wood-frame walls

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.

WOOD RESEARCH Volume 63, Number 5, 2018
Juraj Gigac, MONIKA STANKOVSKÁ, and Mária Fišerová

Improvement of oil and grease resistance of cellulosic materials

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.

WOOD RESEARCH Volume 63, Number 5, 2018
Vladimir Ilyich Fedyukov, Mikhail Vladimirovich Boyarsky, Ekaterina Yuryevna Saldaeva, Maria Sergeyevna Chernova, and Vasiliy Yuryevich Chernov

Dependence of spruce wood resonance properties on its chemical composition

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 found out, the influence of lignin in the latter case being dominant. Continuation of fundamental research in this field has great cognitive value for revealing the nature of unique acoustic properties formation in sonorous spruce wood. Such studies acquire special topicality when dealing with outstanding violins as well as the wood kept for many decades in old buildings subject to demolition.

WOOD RESEARCH Volume 63, Number 5, 2018
Hamza Cinar

Effects of temperature and thickness of wood based boards on formaldehyde emission

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 limits of E1 (≤ 0.10 ppm, EN 717-1), except samples treated at 10°C. In conclusion, the temperature and thickness of wood based boards significantly affect their formaldehyde emissions.

WOOD RESEARCH Volume 63, Number 5, 2018
Mitani Andromachi and Rammou Ekaterini

Cadhesive bond performance of heat- treated fir wood (Abies borrissiregis)

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.

WOOD RESEARCH Volume 63, Number 5, 2018
Mirko Kariz, Milan Sernek, and Manja Kitek Kuzman

Effect of humidity on 3D-printed specimens from wood-pla filaments

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 4, 2018
Hui Ouyang, Zhenling Liu, Lishu Wang, Peng Wanxi, Heping Deng, and Muhammad Aqeel Ashraf

Fungicidal activity and bamboo preservation of Pinus elliottii needles extracts

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 developed as natural bamboo preservative.

WOOD RESEARCH Volume 63, Number 4, 2018
Ľudmila Tereňová, Katarína Dúbravská, and Andrea Majlingová

Influence of the cross-sectional shape of the log elements to seal the log walls under the thermal loading

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.

WOOD RESEARCH Volume 63, Number 4, 2018
Limin Peng, Meihong Liu, Dong Wang, and Boqi Song

Sound absorption properties of wooden perforated plates

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 research.

WOOD RESEARCH Volume 63, Number 4, 2018
Ilyas Deveci, Cevdet Sacli, Turkay Turkoglu, Ergun Baysal, Hilmi Toker, and Huseyin Peker

Effect of SiO2 and Al2O3 nanoparticles treatment on thermal behavior of oriental beech wood

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.

WOOD RESEARCH Volume 63, Number 4, 2018
Zuzana Kamenická, Jaroslav Sandanus, Lukáš Blesák, Kamila Cábová, and František Wald

Methods for determining the charring rate of timber and their mutual comparison

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.

WOOD RESEARCH Volume 63, Number 4, 2018
Ming Chen, Xiangmin Li, and Jianhua Lyu

Influence of dowel diameter and curing time on strength of double dowel joint

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.

WOOD RESEARCH Volume 63, Number 4, 2018
Stanislav Doubek, Vlastimil Borůvka, Aleš Zeidler, and Ladislav Reinprecht

Effect of the passive chemical modification of wood with silicon dioxide (silica) on its properties and inhibition of moulds

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.

WOOD RESEARCH Volume 63, Number 4, 2018
Bin Na, Haiqing Wang, Tao Ding, and Xiaoling Lu

Study on factors affecting the sound absorption property of magnesia- bonded wood-wool panel

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.