MISCIBILITY IN COPOLYMER BLENDS OF POLY(VINYL CHLORIDE-CO-VINYL ACETATE) AND POLY(METHYL-CO-HEXYL ACRYLATE)

The phase behavior in 50/50wt% binary random copolymer blends of poly(vinyl chloride-co-vinyl acetate) and poly(methyl-co-hexyl acrylate) was studied. The blends had a miscibility window and exhibited LCST behavior. The miscibility was determined as a function of composition of each copolymer and displayed in composition-composition diagram [C-C diagram]. The segmental interaction parameters between monomer units comprising the blends were calculated by applying the mean field theory expression to the C-C diagram. Using the segmental interaction parameters, blend interaction parameters which represent the miscibility of the blend system quantitatively, were also estimated. From the calculated values, it was found that the segmental interactions of vinyl acetate unit with other units were strongly repulsive and had significant effect on the miscibility.