木材のレオロジーに関する研究 (V) : 脱リグニン及び酸加水分解の動的弾性率に及ぼす影響

Abstract

In this report we investigate the effect of some chemical treatment on the dynamic Young's modulus of early wood and late wood of Sugi (Cryptomeria japonica D. Don.) by the vibrating reed method. Dimension of the specimen used in this study is about 0.2 mm in tangential, 0.15 cm in radial and 2.5 cm in longitudinal direction, and the apparatus is shown in Fig. 2 schematically. Influence of moisture content relative humidity and grain angle upon dynamic elsatic moduli of the specimen is measured beforehand. The results are shown in Figs. 6 and 7, and in Table 2. The experimental results are as follows: (1) Effect of chemical treatment with NaCl03 and Cl02 is shown in Figs. 8 and 9. Figurs show that the dynamic modulus decreases slowly with decreasing lignin content within the wood fibers in longitudinal direction. (2) Effect of boiling treatment with hydrochloric acid for 15 min. is given in Fig. 10. The Figure shows that fhe maximum value of dynamic elastic modulus is observed at 1 N-HC1. This is consistent with the view that hydrochloric acid, in dilute solution, will have some effects on crystallization but in concentrate, the hydrolysis of hemicellulose and cellulose in the amorphous portion will occur. From the above it seems that lignin in the wood fiber has comparatively a little contribution to the dynamic modulus in this direction, and so the modulus will mainly depend on the holocellulose, especially in amorphous region.