MISCIBILITY OF PVA EVA SYSTEMS BY VISCOMETRY

Viscometric data were applied to characterize the miscibility of poly( vinyl chloride) (PVC)/poly(ethylene-co-vinyl acetate) (EVA) mixtures u sing six samples of EVAs with different vinyl acetate content in the c opolymer. Relative viscosity vs composition plots showed the imiscibil ity of PVC/EVA 31 and PVC/EVA 41 blends. The variation of the reduced viscosity, eta(sp)/C, with the concentration, C, has been studied for 50:50 by weight blends of PVC/EVA 45, PVC/EVA 45A, PVC/EVA 50 and PVC/ EVA 70 in tetrahydrofuran at 25-degrees-C.The presence of a sharp cros sover and a consequent reduction of slope in eta(sp)/C vs C plots show ed that these systems are miscible for a concentration range which cor responds to the regime of dilute solution.