A model of anisotropic swelling and shrinking process of wood
A model of anisotropic swelling and shrinking process of wood
复制标题
木材各向异性膨胀和收缩过程模型
DOI：
10.1007/s002260000074
复制
发表时间：
2001
影响因子：
3.4
通讯作者：
J. Gril
中科院分区：
文献类型：
--
作者：
Hiroyuki Yamamoto;F. Sassus;M. Ninomiya;J. Gril
为了阐明木材在干燥过程中收缩各向异性的根源，并开始了解水分和细胞壁成分之间的相互作用，使用先前报告（第 1 部分）中开发的分析模型模拟了单根木纤维与水解吸相关的收缩过程。将所得数据与本文的实验数据进行了比较。得出以下结论：（1）基质物质作为次生壁的骨架，具有各向同性收缩的趋势。然而，纤维素微纤维作为细胞壁的刚性框架，几乎没有因水的解吸而收缩。结果，木材在干燥过程中各向异性收缩。 S2层中的微纤维角度是与木材干燥时收缩各向异性程度相关的最重要因素之一。 （2）根据模拟，从烘干状态到生坯状态，吸水引起的基体骨架膨胀应变增加了15%（= 150,000微应变）。据此计算出纤维饱和点含水率约为35%，与实验得到的值接近。这些结果提供了木材细胞壁的吸湿膨胀受增强基质假说机制控制的定量证据。
To elucidate the origin of the shrinking anisotropy of wood during the drying process, as well as to begin to gain an understanding of the interaction between the moisture and the cell wall components, the shrinking process of a single wood fiber regarding water desorption was simulated by using an analytical model which was developed in the previous report (Part 1). Resulting data were compared with the experimental ones in this paper. The following conclusions were obtained: (1) The matrix substance, as a skeleton in the secondary wall, tends to shrink isotropically. However, the cellulose microfibrils, as a rigid framework of the cell wall, almost did not shrink at all due to the water desorption. As result, wood shrinks anisotropically during a drying process. The microfibril angle in the S2 layer is one of the most important factors related to the degree of shrinking anisotropy of the wood while drying. (2) According to the simulation, the expansive strain caused in the matrix skeleton by the water sorption increases by 15% (= 150,000 micro-strains) from the oven-dried condition to the green condition. Based on this value, the moisture content at the fiber saturation point is calculated to be about 35%, which is close to the experimentally obtained one. These results give quantitative evidences that the hygroexpansion of the wood cell wall is controlled by the mechanism of the reinforced matrix hypothesis.