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, 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, 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.