DESCRIPTION OF PHASE-BEHAVIOR OF POLYMER BLENDS BY DIFFERENT EQUATION-OF-STATE THEORIES .1. PHASE-DIAGRAMS AND THERMODYNAMIC REASONS FOR MIXING AND DEMIXING

A comparison has been made between the Sanchez-Lacombe equation-of-sta te theory and the theory of Patterson for describing the phase behavio r of various polymer blends. Phase diagrams have been determined as we ll as PVT data, in order to determine the reduction parameters of the polymers used. With these data the phase diagrams were simulated apply ing these two theories. Furthermore, the cause of compatibility or inc ompatibility, i.e., the influence of free volume and enthalpic effects were investigated. Both theories show surprisingly similar behavior w ith respect to the mentioned properties.