Simplified hole theory equation of state for liquid-liquid equilibria of polymer solutions and blends

In our previous work (Wang et al., 1997), the simplified hole theory equati on of state was successfully used for the estimation of the pressure-volume -temperature relationship and vapor-liquid equilibria of a large number of polymers, solvents, and their solutions. Here, we extend the equation of st ate to liquid-liquid equilibria (LLE) calculations for a variety of polymer -solvent and polymer-polymer systems. Analytical expressions for the calcul ation of the LLE are derived, which make the determination of critical solu tion point, spinodal, and binodal curves convenient and reliable. Several t ypes of LLE calculations are carried out, including predictions and correla tions of spinodals and estimations of binodal and spinodal curves. The resu lts indicate that the equation of state is capable of describing fairly the LLE for polymer-solvent and polymer-polymer systems including the upper an d/or lower critical solution temperature phase behavior.