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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.

The compatibility of blends prepared from random copolymers of p-fluorostyrene and o-fluorostyrene with poly(2,6-dimethyl-1 ,4-phenylene oxide) (PPO) and blends of the copolymers with polystyrene (PS) has been examined using differential scanning calorimetry. It was found that compatibility in these systems depends on copolymer composition: copolymers containing from 1 Oto 3S°/o of p-fluorostyrene are miscible with PPO in all proportions. The thermally induced phase separation in these systems was also studied and the existence of lower critical solution temperatures (LCST) was established for all compatible blends. The copolymers were found to be incompatible with PS regardless of composition.

SynopsisThe compatibility of poly(2,6-dimethyl-l,4-phenylene oxide) (PPO) with random copolymers of orthoand para-fluorostyrene as well as with orthoand para-chlorostyrene of various copolymer compositions was examined. The compatibility was studied by DSC and visual observation of film clarity. It was found that copolymers of ortho-fluorostyrene with para-chlorostyrene containing 15-74 mol 7' 0 p-C1S are compatible with PPO in all proportions. Compatibility of the PPO/poly-(ortho -fluorostyrene-co-ortho-chlorostyrene) system was observed for copolymers containing between 15 and 36 mol 70 ortho-chlorostyrene. Copolymers of para-fluorostyrene with para-chlorostyrene, as well as copolymers of para-fluorostyrene with ortho-chlorostyrene appear to he incompatible with PPO a t 210OC.

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