Phase behavior of binary ethylene-propylene copolymer solutions in sub- and supercritical ethylene and propylene

Temperature-pressure and pressure-concentration cloud-point transitions were measured for solutions of ethylene-propylene copolymer (PEP) in ethylene and in propylene in the critical region. The cloud points were visually observed in variable-volume optical cells up to 200°C and 2000 bar. While UCST, LCST, and U-LCST transitions were observed for PEP solutions in propylene, only U-LCST behavior was observed for PEP solutions in ethylene for the molecular weight range investigated (790–96000 g mol ). Statistical Associated Fluid Theory (SAFT) was used to correlate the experimental cloud points.