The strain dependence of stress relaxation in cellulose monofilaments

The stress relaxation behavior of isotropic and oriented cellulose filaments has been studied at 25° and 50°C. and 50% relative humidity at strains between 0.5 and 5%. Log modulus–log time plots were found to be different at different strains, but superposable one upon the other by simple translation along the log time axis. In this manner a master curve for the relaxation modulus may be obtained. This behavior is hypothesized to result from a strain dependence of the relaxation times in which all the relaxation times have the same dependence on strain. The master curves are used to obtain generalized relaxation distribution functions, which are considerably broader for the isotropic filaments than for the oriented filaments.