Theoretical and experimental analysis of polymer molecular weight and temperature effects on the dissolution process of polystyrene in ethylbenzene

The effects of temperature and molecular weight on the polymer dissolution rate were investigated by comparison of the numerical simulation with the experimental observations. The Fickian diffusion equation was modified to predict the non-Fickian behavior by considering the temperature and concentration dependence of diffusion coefficient for moving (swelling) polymer films caused by solvent incorporation. The polymer dissolution process was predicted using the polymer chain disentanglement mechanism, founded on the reptation theory. The temperature and polymer molecular weight dependence of dissolution rate was measured using the laser interferometer technique. As results of simultaion and observations for the dissolution of polystyrenes in ethylbenzene, the dissolution rate increased with increasing temperature and decreasing polymer molecular weight and there was linear relationship between them in logarithmic scale. The experimentally determined values of exponent a and b which indicate the dependence strength of molecular weight and temperature on the dissolution rate were very similar to those theoretically estimated.