杨树浸渍改性处理材尺寸稳定性研究

利用聚乙烯醇缩甲醛改性剂对杨树木材进行浸渍改性,对其改性材的尺寸稳定性进行研究。结果表明:改性材的径向、弦向和体积干缩率与素材相比均有不同程度的下降;从全干到吸水饱和状态的过程中,当改性剂达到一定浓度时,改性材的径向、体积湿胀率与素材相比有明显下降,弦向线湿胀率下降不明显。从气干到吸水饱和状态的过程中,改性材的径向、弦向湿胀率与素材相比均有不同程度的下降;改性材体积湿胀率随着改性剂浓度的上升而呈下降趋势,当改性剂浓度为30%时,改性材体积湿胀率为6.85%,与素材相比下降了5.54%。改性材吸水率随改性剂浓度的上升而下降,最低可达159%;改性材的抗干缩系数(ASE)随改性剂浓度上升而增加,最大可达47.8%。改性材的尺寸稳定性能要明显优于杨树素材。     

杉木浸渍改性材的尺寸稳定性研究

利用聚乙烯醇缩甲醛改性剂对杉木木材进行浸溃改性，对其改性材的尺寸稳定性进行研究。结果表明：改性材的弦向、径向和体积干缩率与素材相比均有不同程度的下降；改性材的弦向、径向和体积湿胀率与素材相比也均有不同程度的下降，但当改性剂浓度超过20％时，下降才较明显；改性材吸水率随改性剂浓度的上升而下降，最大可由改性前的197％下降到改性后的155％；改性材的抗干缩系数（ASE）随改性剂浓度上升而增加，最大可达18．8％。杉木改性材的尺寸稳定性能要明显优于素材。     

阻燃剂WFRJ1改性木材的体积稳定性和涂饰性能

用阻燃剂ＷＦＲＪ１处理大青杨木材并对处理材的阻燃性能、涂饰性能和体积稳定性进行测定。结果表明：ＷＦＲＪ１可用于木制品的阻燃处理。当ＷＦＲＪ１浓度为１０％时,氧指数可达到５０％以上,与水溶性ＲＦ树脂复配,可大幅度提高处理材的抗胀缩率和阻湿率,增加体积稳定性。经ＷＦＲＪ１处理后杨木单板的涂饰性能未受影响。     

Effect of oil impregnation on water repellency,dimensional stability and mold susceptibility of thermally modified European aspen and downy birch wood

Conventional chemical wood preservatives have been banned or restricted in some applications due to human and animal toxicity and their adverse impact on the surrounding environment. New, low-environmental-impact wood treatments that still provide effective protection systems are needed to protect wood. Thermal modification of wood could reduce hygroscopicity, improve dimensional stability and enhance resistance to mold attack. The aim of this study was to investigate if these properties enhanced in thermally modified (TM) wood through treatments with oils. In this study, TM European aspen (Populus tremula) and downy birch (Betula pubescens) wood were impregnated with three different types of oil: water-miscible commercial Elit Träskydd (Beckers oil with propiconazole and 3-iodo-2-propynyl butylcarbamate, IPBC), a pine tar formulation and 100% tung oil. The properties of oil-impregnated wood investigated were water repellency, dimensional stability and mold susceptibility. The treated wood, especially with pine tar and tung oil, showed an increase in water repellency and dimensional stability. However, Beckers oil which contains biocides like propiconazole and IPBC showed better protection against mold compared with pine tar and tung oil. To enhance the dimensional stability of the wood, pine tar and tung oil can be used, but these oil treatments did not significantly improve mold resistance rather sometimes enhanced the mold growth, whereas a significant anti-mold effect was observed on Beckers oil treated samples.     

Preparation of acetylated wood meal and polypropylene composites II: mechanical properties and dimensional stability of the composites

Acetylated wood meals of Sugi (Cryptomeria japonica D.Don) wood were prepared by mechanochemical processing using a high-speed vibration rod mill. Weight percent gain (WPG) of the acetylated wood meals ranged from 7.0 to 35.5 %. Wood–plastic composites (WPCs) containing 50 % acetylated woods were produced by an injection molding technique. The polymer matrix used was polypropylene homopolymer. Maleic anhydride-grafted polypropylene (MAPP) was also used as a compatibilizing agent. The mechanical properties of WPCs in bending and tensile tests were independent of WPG of acetylated wood meals, and the test values for WPCs containing acetylated wood meals were lower than that of unmodified wood meal. The use of MAPP increased bending and tensile strength, but no effect on bending modulus was found. An increase in WPG significantly decreased water absorbability and thickness swelling of WPCs as measured by dimensional stability tests. These results demonstrated that mechanochemical processing is a promising technique for preparing WPC material with improved dimensional stability. The future challenge is to inhibit the decreases in mechanical properties of WPCs containing acetylated wood meals.     

Identification of moisture-induced stresses in cross-laminated wood panels from beech wood (Fagus sylvatica L.)

The crosswise bonding of the layers in laminated solid wood panels results in internal stresses when the humidity varies. The layers hinder one another as a result of the anisotropy of wood. The purpose of this study was to determine the internal stress state in free and constrained swelling. The expansion properties in the three panel directions were measured. Furthermore, the swelling of samples was constrained while the resulting forces were recorded. Hygroscopic warping experiments were carried out inducing a climate gradient within the panels. Afterwards the stresses were calculated from released deformations and non-destructive measurements of the Young’s modulus. The materials used were untreated and heat-treated beech wood, the latter modified in two levels. In addition to homogenously structured panels, treated top layers were combined with an untreated middle layer. Swelling, swelling pressure, warping and internal stresses considerably decreased from untreated to treated wood. If layers from treated and untreated material were combined, stresses and deformations increased as compared to the variants produced only from treated wood. It was concluded that the lower equilibrium moisture content of heat-treated beech wood improves its dimensional stability, which results in smaller deformation differences between the layers. Hence, the stresses were less distinctive.     

氨水添加量对苯酚-甲醛低聚物改性杨木的影响

在氨水存在下,杨木经苯酚-甲醛低聚物浸渍改性后,尺寸稳定性有了较明显改善,力学性能也有所提高。随着氨水添加量的下降,试样的静曲强度呈单峰型变化,且较未改性的试样均有所提高。当氨水添加量为0.5mol时,改性杨木的综合性能最优,其中,静曲强度相对未改性的参比提高了约6.9%,20℃水泡24h的体积膨胀率相应下降了36.2%,其他性能也相应的有所提升。     

Chemical modification of wood by non-formaldehyde cross-linking reagents

Summary The probability of bond between wood components and glyoxal was examined by means of a mechanical method, infrared (IR) spectrometry, and solid state ¹³C-nuclear magnetic resonance (NMR) spectrometry. The successive fixation of a compressed wood by the glyoxal treatment suggested the formation of cross-linkings between wood components and/or wood structures. The IR spectra showed that ester bond as well as ether bond was formed between wood components and glyoxal. The existence of linkages between glyoxal and cellulose was indicated also from the NMR spectra. The addition of glycol to the glyoxal solution was investigated from the viewpoint of stabilizing effect of the linkages. When 0.2 mole ratio of glycol was added to 5–10% glyoxal solution, weight gain and antiswelling efficiency (ASE) were largest, however the addition of excessive amount of glycol did not advance further the weight gain and ASE. When an appropriate amount of glycol was added to the impregnation solution, both weight and ASE did not largely reduce even by the repeated hot water soaking. By the treatment without glycol, the dimensional stability after water soaking was attributed to only restraint of the swelling. On the other hand, when the glycol was added, the dimensional stability was developed not only by the restraint of the swelling but also by the buckling effect.We would like to thank Associate Professor Dr. Umezawa, Wood Research Institute, Kyoto University, for his invaluable support in NMR analysis. Thanks are also due to Dr. Inoue, Wood Research Institute, Kyoto University, for his preparing the wood specimens.     

脲醛树脂改性木材的研究

文中介绍了将缓冲式脲甲醛溶液浸注到木材人部后聚合而形成固化脲醛树脂的木材改进性方法。通过实验，研究分析了处理材抵抗干燥收缩、吸湿膨胀和吸水膨胀的效果。结果表明，脲醛树脂改性处理可显著提高木材干燥、吸湿和吸水时的尺寸稳定性，并对木材有明显的增硬作用。     

丙烯酸酯/石蜡共混乳液处理材疏水性研究

针对石蜡和丙烯酸(酯)在木材防水改良应用方面的优势和不足,提出了利用丙烯酸酯乳液共混改性石蜡乳液。探究丙烯酸酯乳液对复合乳液成膜性及其对复合乳液处理材疏水性能的影响。考察了复合乳液粒径、离心稳定性、成膜性以及处理材吸水率、表面润湿性和尺寸稳定性等。研究结果表明:1)复合乳液可被用于木材浸渍改性处理,复合乳液平均粒径约180.0 nm。2)相比于石蜡乳液处理,复合乳液中丙烯酸酯乳液可协助石蜡在处理材内部形成有效疏水膜层,提高木材疏水性和尺寸稳定性。     

甲基三甲氧基硅烷浸渍改性刨花板及其性能分析

刨花板是家具制造业的首选板材,在潮湿的环境中使用易出现翘曲变形、膨胀及分层等现象。为改善刨花板防潮性能,提高其尺寸稳定性,将甲基三甲氧基硅烷(MTMS)与0.1mol/L的盐酸以4∶1的体积比混合,将混合溶液置于冰浴中超声水解360 min,然后利用MTMS水解溶液对刨花板进行5 min的浸渍处理。分析了改性前后刨花板的润湿性、抗紫外老化性、粗糙度、表面化学结构及物理力学性能。研究结果表明:经MTMS水解溶液浸渍改性的刨花板具有稳定的拒水、拒油及抗老化性能,尺寸稳定性得到改善,板坯的表面密度增加,力学性能提高。     

热处理对三种木材尺寸稳定性的影响

以落叶松、红橡和奥克榄为研究对象,采用不同的常压蒸汽热处理工艺条件,对照未处理材,研究热处理温度和时间对木材尺寸稳定性的影响。结果表明:热处理温度和时间对木材的尺寸稳定性有显著影响;木材吸湿性随温度提高逐渐降低,当热处理温度上升到一定程度时,尺寸稳定性改善趋缓;随着热处理时间延长,木材尺寸稳定性提高;木材高温热处理后吸湿性和吸水性的改善与木材的密度、结构等物理性能相关。     

The effect of acetylation on the mechanical properties, hydrophobicity, and dimensional stability ofPinus sylvestris

Summary Strips and blocks ofPinus sylvestris were acetylated for different periods of time. These, along with control samples, were tested for their tensile modulus, hydrophobicity and dimensional stability. The modulus of elasticity (tensile modulus) for each sample was derived using a statistical approach. The observations in this work suggest that the acetylation process significantly reduces the tensile modulus of the wood compared to its untreated state in an irreversible manner, and that the extent of the deterioration in tensile modulus is a function of the acetylation conditions. Acetylation improved significantly the hydro-phobicity and the dimensional stability of the wood as measured by the roll angle and swelling tests respectively. It appears therefore that acetylation using acetic anhydride in xylene has an optimum set of reaction conditions that compromise between the gains in water repellence and dimensional stability with the deterioration in mechanical properties.We would like to acknowledge the support of Unilever Research in providing the materials testing machine used in this work, and for the supportive discussions with Hickson & Welsh concerning the results     

Improvement of Pinus pinaster wood dimensional stability using cork industry wastes

Summary This article relates to a procedure of preparing solutions for wood treatment by dissolving the condensed waste material from the baking steam of expanded cork board production in organic solvents. These solutions were applied by way of different methods inPinus pinaster wood treatment. The use of these products and methods improved the pine wood dimensional stability giving rise to lower water absorption and swelling. This cork industry waste, is mainly constituted by tannins and waxes, and their solutions are easy to obtain at low cost. A patent application was done.The authors would like to thank the collaboration of our fellow Mr. Paulo Cortiço     

Effects of five additive materials on mechanical and dimensional properties of wood cement-bonded boards

There is a growing desire to improve the properties and use of nonwood plant materials as supplements to wood materials for wood cement-bonded boards (WCBs). This study was conducted to determine the comparative properties of WCBs containing various amounts of discontinuous inorganic fiber materials, such as alkali-resistant glass fiber, normal glass fiber, mineral wool, and nonwood plant materials such as retted flax straw and wheat straw particles. Tested cement-bonded boards were made at wood/additive compositions of 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 (weight percentages). Seventy-eight laboratory-scale WCBs were produced. Various board properties, such as the modulus of rupture (MOR), internal bonding strength (IB), water absorption (WA), thickness swelling (TS), and linear expansion (LE), were studied. The test results showed that three types of discontinuous inorganic fiber used as reinforcing materials in composites significantly enhanced and modified the performance of WCBs. The mechanical properties and dimensional stability of cement-bonded board were significantly improved with increasing amounts of the additives. MOR and IB were increased; and WA, TS, and LE of boards were reduced by combination with the inorganic fiber materials. The results also indicated that combination with retted flax straw particles only slightly increased the MOR of boards, and wheat straw particles led to marked decreases in all the mechanical properties and the dimensional stability of WCBs.Part of this report was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000     

国外结构人造板尺寸稳定性的研究技术

国外结构人造板(如定向结构板、大片刨花板、华夫刨花板等)主要用作建筑材料,对产品的尺寸稳定性要求很高,许多研究者在如何提高产品尺寸稳定性方面作了大量的研究工作。文中综述了大量的科研成果,介绍了国外结构人造板尺寸稳定性的研究技术,包括引起结构人造板尺寸不稳定的缘由,结构人造板尺寸稳定性的评价方法,影响结构人造板尺寸稳定性的工艺因素以及提高结构人造板尺寸稳定性的措施。     

Characteristics of fast-growing wood impregnated with nanoparticles

Falcataria moluccana or sengon is one of the fast-growing wood species widely grown in Indonesia.However,its wood is low quality with low density,and poor strength,durability,and dimensional stability.This study determined the effects of impregnation with monoethylene glycol(MEG)and nano-SiO2 on the characteristics of sengon wood,including its dimensional stability and density.Impregnation with MEG and nano-SiO2 had a significant effects on dimensional stability in terms of the weight percent gain,anti-swelling efficiency,water uptake,bulking effect,and density.The impregnated wood was examined by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray diffraction.The results show that MEG and nano-SiO2 were distributed homogeneously into cell walls of wood treated with 0.5%MEGSiO2.     

Properties of Esterified Wood Prepared with Maleic Anhydride ／ Tetrabr Omophthalic Anhydride ／ Glycerol Mixture

For overcoming disadvantages of wood, an esterification process was employed and tetrabromophthalic anhydride (TBPA) was used as a reactive chemical agent to prepare an esterified wood with the high dimensional stability, flame resistance, and resistance to biodegradation from water-leaching. The experimental results indicated that esterification of wood plus maleic anhydride / tetrabromophthalic anhydride / glycerol could endow wood with dimensional stability, the antiswelling efficiency during water absorption (ASEw), reduction in water absorptivity (RWA), antiswelling efficiency during moisture absorption (ASEm),moisture excluding efficiency (MEE), and oxygen index (OI) of treated wood increased with an increase in the weight percent gain(WPG). And the treated wood showed great decay resistance and resistance to water leaching, too.     

Wood defects during industrial-scale production of thermally modified Norway spruce and Scots pine

This research investigates wood defects, particularly the formation of surface cracks, during the production of thermally modified wood and its exposure to cyclic moisture changes. Boards of Norway spruce and Scots pine originating from different steps within the production of ThermoWood® were collected and wood defects were investigated at macroscopic and microscopic scale. Subsequently, the wood was exposed to capillary wetting cycles to record its sensitivity towards cracking. After the modification process, typical anatomical defects of conventional kiln-drying became more frequent and severe, with the magnitude being to some extent depending on the presence of defects in the raw material. At microscopic scale, damages to ray parenchyma and epithelial cells as well as longitudinal cracks within the cell walls of earlywood tracheids were evident in thermally modified wood. Despite a lower water uptake and higher dimensional stability, thermally modified wood was more sensitive to surface cracking during wetting cycles than unmodified wood, i.e. at the outside face of outer boards (near bark). For limiting surface cracking of thermally modified wood during service life, the use of high-quality raw material, the exposure of the inside face of the boards (near pith) and the application of a surface coating are considered beneficial.     

Moisture sorption and swelling of Norway spruce [Picea abies (L.) Karst.] impregnated with linseed oil

Abstract

The moisture sorption and swelling of spruce specimens impregnated with linseed oil and unimpregnated controls were studied in two sorption experiments: from 0 to 55% relative humidity (RH) and from 55% RH to water saturation. Sorption isotherms were also determined using a sorption balance. The impregnated specimens had lower rates of both moisture sorption and swelling than the unimpregnated controls; however, there was no significant difference in final moisture contents. In addition, the linseed oil impregnation did not improve the dimensional stability of the wood; in most cases the specimens impregnated with linseed oil swelled more than the unimpregnated controls. For the impregnated specimens, reductions in swelling rates were in most cases seen without corresponding reductions in final swelling. The moisture sorption rate was reduced for the impregnated specimens but there were generally no reductions in equilibrium moisture content.