The Mechanism of Improvement of Physical Properties of Moso Bamboo (Phyllostachys pubescens) with Increasing Age II. Relationship between dynamic viscoelastic properties and cell wall components

摘要

This paper aims to elucidate the factors related to improvement of physical properties of bamboo as a material with increasing age. In order to achieve the purpose, the temperature dependence of the dynamic viscoelastic properties in the green condition of moso bamboo (Phyllostachys pubescens) at various ages (about 40 days 9 years since shooting) was measured. In addition, the content of cellulose, hemicellulose, Klason lignin, acid-solubld lignin and hot-water extractives was obtained by chemical analysis. The results obtained were as follows: the dynamic modulus of elasticity and the loss modulus of elasticity increased and their temperature dependence changed with increasing age. From the temperature dependence of tan 6, it was found that the softening temperature rose with increasing age. The Klason lignin content increased and the acid-soluble lignin content decreased with increasing age. These changes were remarkable at early ages, and the temperature dependence was still changing little by little even as the bamboo became older. These results lead to the conclusion that, in the period up to about 80 days from shooting, the physical properties of moso bamboo are affected by the amount and the degree of polymerization of lignin, and after the ratio of components becomes constant, some changes of the quality of lignin affect the physical properties of moso bamboo.