汽蒸处理对木材渗透性的影响

试样（２×２×５ｃｍ）在温度１２０℃和１００℃两种饱和水蒸汽条件下分别汽蒸处理８小时，然后置于大气中干燥至含水率为１０％左右时，采用水上升置换气流法进行渗透性测定。汽蒸试样的渗透性分别与其纵向相邻接的未汽蒸、含水率约１０％的对照比较，并进行成对比较分析ｔ检验。试验结果表明，各树种的木材性质不同，汽蒸作用引起木材解剖上、化学上的变化也不同，因而汽蒸处理对木材渗透性的影响各异。红松气干边材、心材经１２０℃和１００℃汽蒸处理后渗透性分别较未汽蒸者提高约６０、９０％和４０、１３０％；长白鱼鳞云杉生材边材经１２０℃汽蒸后和气干心材经１００℃汽蒸后渗透性分别较未汽蒸者约提高３２６和８０％；成对比较分析ｔ检验，汽蒸试样与未汽蒸试样渗透性之间差异可靠性为９０－９９．９％；汽蒸试样渗透性获得提高的原因均系汽蒸后纹孔膜和纹孔塞发生开裂的结果。但汽蒸长白鱼鳞云杉生材心材、气干边材和心材及臭冷杉生材心材、气干边材和心材的渗透性则未获得提高。     

3种不同处理方法对木材渗透性影响的研究

本文通过对长白鱼鳞云杉和臭冷杉生材分别进行普通气干处理和酒精置换处理以及对其气干材进行水浸处理,研究了这３种不同处理方法对木材气渗透性的影响及其影响机理。研究结果表明,长白鱼鳞云杉边材、心材和臭冷杉心村的生材经普通气干处理后,其气体渗透性较低,分别约为０．１１４、０．０４５和０．１１１ｄａｒｃｙ;长白鱼鳞云杉边材、心材和臭冷杉心材的生材经酒精置换处理后,其气体渗透性分别约为１１．７１３、０．０７４和０．１４４ｄａｒｃｙ,比普通气干处理对照组试样的平均渗透性分别增加约１０１．５倍、６２％和３０％,ｔ检验表明,前者差异非常显著,但后两者差异不显著;已气干１８个月的长白鱼鳞云杉边材、心材和臭冷杉心材经水浸处理后,其平均气体浸透性较处理前分别增加约８５％、４９％、６５．５％,ｔ检验表明差异均显著。长白鱼鳞云杉生材边材经     

黑木相思木材物理性质株内变异研究

研究我国黑木相思木材主要物理性质的株内变异规律。结果表明:黑木相思木材各项物理性质在树干南北向差异不显著,径向差异均明显大于纵向差异,株内变异主要是径向差异引起。生材含水率自心材区到边材区递减,木材密度的径向变化趋势则基本相反。木材干缩和湿胀率自心材向边材递增;而差异干缩在外部心材处最大。木材吸湿平衡含水率的径向变化趋势与吸湿滞后系数相反。实际生产应考虑黑木相思木材物理性质株内径向差异,制定科学合理干燥工艺。     

黑木相思株内木材基本材性变化与树龄关系的研究

对不同树龄和径向位置黑木相思木材的物理和主要力学性质测定研究表明:黑木相思株内边材、心材密度和主要力学性质随着树龄的增大而增大,径向和弦向的体积干缩率随着树龄的增大而减小;相同树龄黑木相思的边材密度和力学性能比心材小,干缩率比心材大.因此,在利用黑木相思时应对树龄、心边材径向位置加以特别考虑.     

锯割落叶松的修锯技术

落叶松材质较硬,如果锯条修整不当,就会降低锯材质量和生产效率。根据我们多年的修锯经验,要克服这种不利因素,首先要了解落叶松的性质、特点,然后根据木材含水率和气温的变化,正确调节锯条各部参数,才能提高锯材质量、出材率和生产效率.一、落叶松的性质、特点1.一般特性:落叶松容积重较大,材质较硬,边材较宽。由于新伐材(生材)边材的含水率比心材高,冬季木材结冻后边材比心材硬,锯割时易向心材部分跑锯。材质结构粗糙,夏、秋季锯割,材面易起毛,增大     

降香黄檀树皮率、心材率及木材密度研究

对降香黄檀（Dalbergia odorifera）的树皮率、心材率，木材密度进行了研究。结果表明：降香黄檀树皮体积百分率及质量百分率平均值分别为20．14％、13．77％；心材百分率平均值为30．53％，心材形成的年龄为9～15a；生材密度平均值为1．064g／cm^3；基本密度平均值为0．715g／cm^3；生材含水率平均值为49．21％。降香黄檀树皮体积百分率及质量百分率均随着树高的增加而增加；生材密度及心材率随着树高的增加而减少；基本密度随着树高增加，呈大-小-大-小的趋势变化；生材含水率随着树高的增加，呈小-大-小-大的趋势变化。     

Study on Bark Percentage, Heartwood Percentage and Wood Density of Dalbergia odorifera

对降香黄檀（Dalbergia odorifera）的树皮率、心材率，木材密度进行了研究。结果表明：降香黄檀树皮体积百分率及质量百分率平均值分别为20．14％、13．77％；心材百分率平均值为30．53％，心材形成的年龄为9～15a；生材密度平均值为1．064g／cm^3；基本密度平均值为0．715g／cm^3；生材含水率平均值为49．21％。降香黄檀树皮体积百分率及质量百分率均随着树高的增加而增加；生材密度及心材率随着树高的增加而减少；基本密度随着树高增加，呈大-小-大-小的趋势变化；生材含水率随着树高的增加，呈小-大-小-大的趋势变化。     

桉属木材的化学性质

桉属木材的正常材与应张木之间的化学组成有明显变异,另外边材的淀粉含量和抽提物类型也存在广泛差异,Kino(一种丹宁物质)和无机盐类亦不相同,同时心材的含水率比边材高。     

15年生桉树生材性质研究

为研究大径级桉树人工林木材的基本木材性质,采用排水法、质量法对15a生桉树人工林木材的生材密度、基本密度、树皮率、心材率、生材含水率等指标进行了测试。结果表明:15a生桉树的树皮体积百分率、树皮质量百分率、生材密度、基本密度、生材含水率分别为11.47%、11.88%、1.01g·cm-3、0.53g·cm-3和92.3%。     

5年生大花序桉生材性质研究

采用质量法和体积法测定了5 a生大花序桉树皮体积百分率、质量百分率、心材率、含水率、生材密度、基本密度等基本木材性质,旨在为大花序桉的人工培育及木材利用提供理论依据。结果为,5 a生大花序桉的树皮体积百分率为23.23%,树皮质量百分率为19.89%,心材率为19.91%,含水率为101.64%,生材密度为1.12 g·cm^-3,基本密度为0.54 g·cm^-3。     

Profile of bordered pit aspiration in Cryptomeria japonica using confocal laser scanning microscopy: pit aspiration and heartwood color

Nine trees of Cryptomeria japonica from six elite tree clones with a broad range of heartwood colors were selected. The profiles of pit aspiration percentage (ASP) of earlywood and latewood from pith to bark for green and air-dry conditions were determined to study the relationship between heartwood color and pit aspiration. Confocal laser scanning microscopy (CLSM) observations showed that the ASP of earlywood was low in sapwood and high in heartwood in the green condition. Pit aspiration increased in intermediate wood when compared with sapwood. On the other hand, latewood pits did not aspirate during heartwood formation. Comparing the air-dry condition with the green condition, sapwood pits aspirated during drying in both earlywood and latewood; however, there was no significant difference in pit aspiration of heartwood. There was no significant difference between samples with red and black heartwoods for ASP. The difference in ASP between individual trees was larger than that by heartwood color. The general advantage of CLSM over light microscopy is that serial optical sections along the Z axis can be obtained for any moisture condition, without the need for thin sectioning or embedding.     

Influence of combined hydro-thermal treatments on selected properties of Turkey oak (Quercus cerris L.) wood

A combined effect of steaming and heat treatment was imposed on green Turkey oak wood, both for sapwood and heartwood. Steaming was carried out in an autoclave at 100–120–130°C whereas heating was carried out in an oven for 2?h at 120–180°C. Equilibrium moisture content at dry, intermediate and moist state both in desorption and adsorption, swelling, cup, twist, color change, and spectral reflectance measures were registered. Swelling and water absorption decreased due to the hydro-thermal treatment. During adsorption, heartwood showed a higher hygroscopic inertia compared to sapwood and this difference increased with temperature. Cup increased with temperature in the steaming process. Twist seemed to be affected more by quality of original trunks than treatments. The wood color was more sensitive at a steaming temperature of 130°C combined with heat treatment at 180°C. Transitional treatments assured more reliable results on homogenization of hue between sapwood and heartwood.     

Fuelwood characteristics of tree species in homegardens of Kerala, India

Indiscriminate use of natural resources in the past has lead to fuelwood shortages in many parts of the tropical world. To surmount this domestic energy crisis, not only degraded sites must be planted with trees having high fuel value potential, but also agroforestry promoted on arable lands. To enable choice of species for such energy plantations/agroforests in the humid tropics of peninsular India, we assessed the heat of combustion and physical properties that determine combustion of phytofuels, such as ash content, specific gravity and moisture content. Bark and wood samples of 45 multipurpose tree species in the homegardens of Kerala, India and three fuel materials of local importance (coconut [Cocos nucifera] endocarp, dried coconut spathe and dehiscent rubber [Hevea braziliensis] pericarp) were evaluated. Variations abound in the calorific values and physical properties of species and tissue-types. In general, heat of combustion and specific gravity followed the sequence: heartwood > sapwood > bark, while mean ash percentage followed a reverse order (bark > sapwood > heartwood). Ash content had a negative correlation with heat of combustion, but specific gravity exerted a positive influence. Furthermore, ash content and wood specific gravity were inversely related. Although green moisture content increased in the order: bark < heartwood < sapwood, it failed to show any predictable relationship with heat of combustion.This revised version was published online in November 2005 with corrections to the Cover Date.     

Effects of temperature and moisture content on selected wood mechanical properties involved in the chipping process

The effects of temperature and moisture content on selected mechanical properties associated with the chipping process were evaluated. In chipping, mechanical properties such as shear parallel to the grain, cleavage, and bending are involved. Matched samples of heartwood and sapwood were obtained from freshly harvested logs of black spruce and balsam fir to determine the variation of the studied mechanical properties between ?30 and 20 °C, at intervals of 10 °C. Moisture content (MC), basic density (BD), and annual ring width (RW) were measured for each sample. For both wood species, temperature had a significant effect on all mechanical properties under freezing conditions (below 0 °C). This effect was more important for sapwood than for heartwood, which was explained by the difference in MC between these two types of wood. Between 0 and 20 °C, temperature and type of wood did not show any significant effect on the mechanical properties. Multiple regression models were obtained to predict the mechanical properties. These regressions showed that MC was the most important factor to explain the mechanical properties below 0 °C. However, for temperatures of 0 °C and higher, BD was the principal factor to predict the mechanical properties. RW was not a significant factor to predict any mechanical property. Cleavage was the most sensitive one to changes in temperature followed by shear, modulus of rupture, and modulus of elasticity. These results could be of great importance in the chipping process.     

观光木的生材性质研究

对观光木的生材密度、含水率、树皮率及心材率进行测定分析,结果表明:观光木的生材密度从髓心向外呈先减小再增大的趋势,随着树高的增加,亦呈先减小再增大的趋势,其平均值为0.873 g.cm-3;基本密度自髓心向外逐渐增大,随着树高增加,呈先减小后增大再减小的趋势,其平均值为0.423 g.cm-3;含水率从髓心向外呈减小的趋势,随着树高的增加,呈先增大后减小再增大的趋势,其平均值为108.4%;树皮的体积百分率及质量百分率均随着树高的增加而增加,其平均值分别为13.5%、15.8%;心材率随着树高的增加而减少,心材百分率平均值为15.6%。     

Soft X-ray observation of water distribution in the stem ofCryptomeria japonica D. Don I: General description of water distribution

Water distribution in green stems ofCryptomeria japonica D. Don was observed by soft X-ray photography. In the sapwood, much water was present and evenly distributed. In the intermediate wood (the white zone), little water was present. The intermediate wood appeared in all cross sections of the stem and separated the heartwood from the sapwood in the intertracheid water connection. Maldistribution of water was generally observed in the heartwood, and three types of water presence were distinguishable: a “wet area” with accumulated water, a “dry area” with little water, and a “moderate moisture area” with intermediate accumulation. The distribution pattern and amount of water in the heartwood varied dramatically among and even within trees. Separation of the heartwood from the sapwood in the intertracheid water connection suggested that the presence of water in the heartwood was caused by rewetting of the tracheid lamina that occurred after heartwood formation. The maldistribution of water in the heartwood suggested that a difference in the process of rewetting causes both uneven distribution and the various types of water presence.     

Physical and chemical characteristics of the blackened portion of Japanese persimmon (Diospyros kaki)

The heartwood of the Japanese persimmon tree (Diospyros kaki) becomes black on rare occasions and has been highly esteemed as a substitute for ebony. We attempted to clarify how the physical, mechanical, chemical, and biodegradation properties differ between sapwood and blackened heartwood. The specific gravity, equilibrium moisture content, modulus of rupture, and modulus of elasticity in the blackened heartwood were higher, and the loss tangent was lower, than those in sapwood. Furthermore, the blackened portion was more resistant to fungal and termite attacks. A section of heartwood was dark-brown, and the specific gravity and mechanical properties of this portion were slightly lower than those in sapwood. The dark-brown portion was speculated to be a sign or interrupted state of fungal attack. The blackening substance was bound tightly to cell wall components and could not be extracted with any of the organic solvents used. The findings of trace element analysis using inductively coupled plasma-mass spectrometry showed that the boron content was markedly high in the blackened portion. The findings obtained here suggest a role of boron in the antifungal properties and the blackening phenomenon of Japanese persimmon.Part of this work was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000