MOLECULAR-WEIGHT AND HEATING RATE DEPENDENCE OF THE CLOUD POINTS OF POLYSTYRENE POLY(2-CHLOROSTYRENE) BLENDS

Cloud points of polystyrene/poly(2-chlorostyrene) blends of narrow molecular weight distribution were measured with changing heating rate and molecular weight of polystyrene. Cloud points were also measured for blends containing various amounts of the plasticizer di-n-butyl phthalate. A large heating rate dependence of cloud points is observed at very small heating rates when no or a small amount of the plasticizer is contained. Cloud points extrapolated to zero plasticizer content are very different from directly observed cloud points of the binary blends, especially for large molecular weight samples. This is explained by the very slow phase separation kinetics of this system. The Flory-Huggins interaction parameter chi was calculated from the extrapolated cloud points using the spinodal condition. The chi parameter is positive and has a very weak temperature dependence.