DESCRIPTION OF PHASE-BEHAVIOR OF POLYMER BLENDS BY EQUATION-OF-STATE THEORIES

A previous study has shown that the Equation-of-State theories of Sanc hez-Lacombe and of Patterson give similar predictions for the descript ion of polymer blends. These predictions concern phase behavior, exces s volumes, the influence of pressure on miscibility and the causes of miscibility. In the present work, the modified cell model of Dee and W alsh and the Simha-Somcynsky theory are investigated with respect to t hese properties. It is found that the theory of Dee and Walsh yields r esults similar to the previously investigated theories, whereas the Si mha-Somcynsky theory does not. However a modification of the latter th eory for mixtures again results in predictions similar to that of Dee and Walsh, and the earlier investigated theories.