Structure Analyses of native celluloses on the basis of 2 phase crystal model

点击翻译按钮获取中文摘要

The research was mainly extended into two directions. One is to produce advanced cellulosic materials by reorientating highly crystalline cellulose microcrystals. The other is to apply 2 phase crystal model in order to explain the varietal differences of X-ray diffraction data. Regarding reorientation of cellulose microfibrils, we have investigated the behavior of microcrystals in the aqueous suspension under strong static magnetic fields up to 20 Tesla (20000 Gauss). The stronger the magnetic field, the better orientation was achieved. Cellulose microcrystals was oriented with their molecular axes perpendicular to the direction of the field. This behavior was also confirmed by calculation of the diamagnetic susceptibility of the crystal. Regarding the applicability of 2 phase crystal model, we first investigated 12 highly crystalline native celluloses, and measured typical d-spacings for celluloses (four most intense reflections; corresponding d-spacings are about 0.6, 0.53, 0.39, 0.26 nm) by an X-ray powder diffractometry method. By discriminant analyses of observed d-spacing data it was possible to distinguish native celluloses into two category ; one is Agal-Bacterial type cellulose being rich in Ialpha component, and the other is Cotton-Ramie type celluloses dominated by Ibeta. According to this analyses, native celluloses from terrestrial plants (including wood celluloses) were all discriminated into Cotton-Ramie type, cellulose dominated by Ibeta component.