1993 年 42 巻 473 号 p. 153-156
In this report, the piezoelectricity and the crystallinity of Hinoki treated with sodium hydroxide for a long period were investigated. The results obtained are summarized as follows.
(1) A remarkable increase in piezoelectric moduli was observed by the treatment of sodium hydroxide, though there was a decrease in the degree of crystallinity of wood. However, the piezoelectric moduli of wood treated for one year decreased to a half compared with those treated for three months.
(2) By the alkali treatment, the degree of crystallinity and crystallite size of the treated wood decreased, and the 2θ002 shifted toward low angle. These results suggest that some change in crystalline structure took place in wood.
(3) The temperature variation of the plane distance of cellulose crystallites in the alkali-treated wood was measured. The lattice widening took place in the (002) plane with increasing temperature. With increasing period of alkali treatment, the temperature variation of the ratio Δd/d of the treated wood decreased compared with that of the untreated wood. It may be considered that new hydrogen bonds appeared on the (101) plane and they restrained the widening of the (002) plane distance due to thermal expansion. In the case of Ramie cellulose, the temperature variations showed a tendency approximately similar to those of wood.
(4) It is assumed that the increase of the piezoelectric moduli of wood and cellulose occurs by piezoelectric polarization due to the hydrogen bond which is formed by the change in crystalline structure of cellulose.