SOLID-LIQUID-LIQUID EQUILIBRIA IN POLYMER-SOLUTIONS

The thermodynamics of solid-liquid equilibrium is applied to binary sy stems including a semicrystalline polymer and a solvent. Group-contrib ution activity coefficient models are used for describing the nonideal behavior of the liquid phase. The solid polymer properties are obtain ed via group-contribution methods and tested for consistency. Methods for the simultaneous solution of the solid-liquid and liquid-liquid eq uilibrium are presented. The full phase envelope of polymer solutions can be predicted, and the use of the empirical solubility parameter ap proach is avoided. The effects of polymer semicrystallinity and molecu lar weight on the solid-liquid equilibria are displayed, and a compari son of our predictions with experimental data is performed.