Establishment of Method for Measuring Molecular Orientation in Wood by Fluorescence Method and Its Application

1.研究了利用木材本身发出的荧光测量木质素分子取向的方法。通过外推一条样品厚度与其比值为零的直线，得到了荧光强度的每个偏振分量与偏振器和分析器平行于纵向的校正比。根据这些比例计算出的分子取向度在0.003-0.094.2之间。经高乙酰化处理后，日本原产阔叶木分子取向度的未校正值几乎不变，而针叶材和劳恩木的分子取向度显著降低。这一显著增加是由于高度乙酰化处理导致木质素本身的荧光强度增加所致。荧光分子在木材中的引入受到抑制，但荧光分子染色的木材成分是否发生变化尚不清楚。用荧光显微镜观察了木材细胞壁的荧光强度分布。木材本身在复合中板和次生壁外层附近发射的荧光较强，在中板的荧光强度几乎不随荧光分子的引入而增加。乙酰化的Woo也有类似的趋势。研究了木材结构因素与木材水热软化的关系。在各种条件下，分子在非晶区的取向度对比杨氏模数的影响最大。结晶度和Klason木素含量值较小的木材，在加热和水软化时，其比杨氏模量值较小，断裂应变较大。

1. We investigated the method for measuring the molecular orientation of lignin by the use of the fluorescence emitted from wood itself. The corrected ratio of each polarized component of fluorescence intensity to that with the polarizer and the analyzer aligned parallel to the longitudinal direction was obtained by extrapolating a straight line of sample thickness vs. its ratio to zero. The degree of molecular orientation calculated from these ratios ranged from 0.003 to 0.094.2. The uncorrected value of degree of molecular orientation of hardwood native to Japan which was obtained from the orientation of fluorescent molecules introduced into wood was hardly varied by a highly acetylating treatment, whereas that of softwood and lauan was markedly decreased by it. This marked increase resulted from the increase in fluorescence intensity of lignin itself due to the highly acetylating treatment. The introduction of fluorescent molecules into wood was inhibited by the treatment, but it is unclear whether wood components dyed with the fluorescent molecules change or not.3. The distribution of fluorescence intensity in the cell wall of wood was observed with a fluorescence microscope. The fluorescence emitted from wood itself near the compound middle lamella and outer layer of secondary wall was strong, and the fluorescence intensity in the middle lamella was hardly increased by the introduction of fluorescent molecules into wood. The acetylated woo had a similar tendency.4. The relationship between structure factors and softening of wood due to heat and water was investigated. The degree of molecular orientation in the amorphous area had the greatest effect on the specific Young's modulus under every condition. Woods with small values of the degree of crystallinity and Klason lignin content have small values of specific Young's modulus and large values of breaking strain when they are softened with heat and water.