MISCIBILITY BEHAVIOR OF BLENDS OF POLY(VINYL CHLORIDE) WITH POLY(METHYL METHACRYLATE-CO-STYRENE) COPOLYMERS

Poly(vinyl chloride) (PVC) is shown to be completely miscible in the m elt with a poly(methyl methacrylate-co-styrene) (P(MMA-co-St)) copolym er having a low styrene content (0-10 wt%). In blends of PVC with a lo w molecular weight P(MMA-co-St) copolymer containing 20 wt% of styrene , a lower critical solution temperature is found at approximately 170 degrees C. For blends of PVC with P(MMA-co-St) copolymers containing 3 0 wt% of styrene, immiscibility is found over the whole temperature ra nge (150-210 degrees C) and independently of the molecular weight of t he copolymer. These experimental results have been modelled using a me an-field binary interaction model of the Flory-Huggins theory. The bin ary interaction energy density for this blend system correctly predict s the homogeneous dispersion of methyl methacrylate/butadiene/styrene (MBS) graft copolymers in a PVC matrix. Copyright (C) 1996 Elsevier Sc ience Ltd.