Fundamental Study on Wood Quality by Electrical Conduction and Gas Permeability

研究了20种阔叶木和落叶松木材的电导率和透气性与比重和木材形态的关系，以了解评价木材质量的物理性质的一个基本方面。另一方面，单位木材体积含水率的影响与基本密度高度相关。因此，树种间电导率的变化主要是由于木材比重与含水率的差异以及吸附水随含水率的物理变化所引起的。细胞壁的内部结构和细胞尺寸可能是物种间差异的另一个因素，因为细胞壁的电导率本身存在物种间的差异，并与管胞的平均微纤丝角相关。结果表明，如果湿度与…之间的关系尽管导管分子和管胞被认为是木材中的主要流动通道，但透气性与其管腔的体积百分比并不相关。这是因为木材中的流动通道应该更复杂，既有元素间的结构，也有导管和坑的闭塞。因此，将单位横截面积上的导管半径和导管总数的实测值与串联应用这两个模型的渗透率测量值进行了比较。在导管直径变异较大的树种和导管闭塞的树种中，两者之间的一致性较好，但在有梯状穿孔和无血管闭塞的树种中两者之间的一致性较好。此外，还可以计算单位横截面积的闭塞面积占总血管面积的百分比。从上述结果来看，透气性是木材结构分类的综合指标，因为它对树种间通道的差异很敏感。较少

The electrical conductivities and air permeabilities of 20 hardwood species and Larix were studied in relation to specific gravity and wood morphology in order to understand a fundamental aspect of the physical properties for evaluating wood quality.The conductivity at a given moisture content had large variation among species. On the other hand, the effect of moisture concentration per unit wood volume was highly correlated to basic density. Therefore the conductivity variation among species was assumed to be mainly caused by the difference of moisture retention with wood specific gravity and also by the physical change of adsorbed water with moisture retention. The intra-structure of cell wall and the cell dimension may be another factors in the difference among species, because the conductivity of cell wall itself was shown to have the variation among species and to be correlated to average microfibril angle in tracheid. The results suggested that, if the relationship between moistu … More re retention and wood structure was sufficiently realized, conductivity could be a reasonable index for specific gravity as well for moisture content.Although vessel element element and tracheid were supposed to be main flow passages in wood, air permeability could not be correlated to the volumetric percentage of their lumens. It is because the flow passages in wood should be more complicated by interelements structure and also by occlusion of vessels and pits. Therefore the measured values of vessel radius and total number of vessels per unit cross sectional area were compared with the estimated values from permeability measurement by aplying the two elements model in series. A reasonable agreement between the two was found out in the species of diffuse-porus hardwoods with scalariform perforation and without occlusion of vessels, but was not in the species with high variation in vessel radius as well as for those with occluded vessels. Furthermore the percentage of occluded area to total vessel area per unit cross sectional area may be calculated. From the results mentioned, air permeability is recognized as synthetic index for wood structural classification because of its sensibility for the difference in passage among species. Less