Changes of crystallinity in wood cellulose by heat treatment under dried and moist conditions

The different effects of heat treatment on wood, especially on the cellulos e crystallites of wood under ovendried and highly moist conditions, were in vestigated by Xray diffractometer. Heat was found to increase significantly the crystallinity of wood cellulose; moreover, almost twice as much crysta llization was observed after heat treatment of spruce and buna under a high ly moist condition than under the oven-dried condition. In pure cellulose a lmost the same crystallization was observed under both the conditions, wher eas more crystallization occurred in wood cellulose than in pure cellulose. Absolute crystallization was observed for the wood species and pure cellul ose under both conditions, considering the thermal decomposition of the amo rphous region in addition to crystallization. Our results suggested that ot her components accomparying wood cellulose were involved in the increase of crystallinity by heat treatment, and that wood cellulose contained more qu asicrystalline regions than pure cellulose. Moreover, calculated apparent a ctivation energies revealed that crystallization and decrystallization in p ure and wood cellulose under heat treatment of highly moist condition were somewhat easier than those under the oven-dried condition. The behavior of the piezoelectric modulus d'(25) almost paralleled that of crystallinity.