CELLULOSIC SOLID FILMS EXHIBITING CHOLESTERIC LIQUID-CRYSTALLINE ORDER .1. TENSILE CREEP IN VACUO FOR ETHYL CELLULOSE AND HYDROXYPROPYL CELLULOSE

Ethyl cellulose (EC) and hydroxypropyl cellulose (HPC) films were cast under different conditions and were observed optically. The creep behaviour of those films was determined in vacuo as a function of applied stress or temperature and was analysed on the basis of the Eyring thermally activated process. EC and HPC films cast from liquid crystal-forming systems remained cholesteric liquid crystalline order (the cholesteric sense was different in each case), whereas EC film cast from non-liquid crystal system (benzene) had no liquid crystalline order and was amorphous. The Eyring activated process could be applied to the creep behaviour of our films and activated parameters could be evaluated. The activated volume V was of the order of 1 nm3 and greatly depended on the casting conditions and testing temperature. The value of V tended to decrease as the liquid crystalline order increased. The value of V was smaller than the size of liquid crystalline domain.