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 5, 2018
Sedigheh Saeedi, Mohsen Bahmani, Miha Humar, and Farhad Kool

Effect of tree diameter classes on the properties of persian oak (Quercus brantii Lindl.) wood

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.

WOOD RESEARCH Volume 63, Number 5, 2018
Zhenzhong Tang, LILI YU, Yi Zhang, Lizhi Zhu, and Xiaojun Ma

Effects of nano-SiO2/polyethylene glycol on the dimensional stability modified ACQ treated southern pine

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.

WOOD RESEARCH Volume 63, Number 5, 2018
Saban Kart, Ergun Baysal, Turkay Turkoglu, Mustafa Kucuktuvek, Huseyin Peker, Caglar Altay, Ahmet Gunduz, and Hilmi Toker

The effect of natural weathering on change in the color of heat treated and varnished scots pine and oriental beech woods

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.

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).