Phase behavior in copolymer blends of polystyrene and poly(o-chlorostyrene-co-p-chlorostyrene)

The miscibility of random copolymers of o-chlorostyrene and p-chlorostyrene [P(oClS-pClS)] with polystyrene (PS) has been studied by differential scanning calorimetry (DSC). A miscibility “window” was found, extending in copolymer composition from about 68 to 98 mole % o-chlorostyrene at a temperature of 150 °C. The maximum in the miscibility window occurred at approximately 170 °C and a composition of 83 mole % o-chlorostyrene. This result differs only slightly from theoretical predictions based on interaction parameters previously calculated from miscibility behavior in blends of poly(2,6-dimethyl-1,4-phenylene oxide) with P(oClS-pClS), poly(styrene-co-o-chlorostyrene) and poly(styrene-co-p-chlorostyrene). The implication of this result for the numerical values of the six interaction parameters required to describe these blends is discussed