MISCIBILITY BEHAVIOR OF DI(ETHYL-2-HEXYL) PHTHALATE IN BINARY AND TERNARY CHLORINATED POLYMER BLENDS

The miscibility behavior of ternary blends made by the addition of di( ethyl-2 hexyl) phthalate (DOP) to a mixture of chlorinated polymers wa s investigated by differential scanning calorimetry. Two chlorinated p olymer mixtures were selected: polyvinyl chloride (PVC) with a chlorin ated polyethylene containing 48 wt % Cl (CPE48), and PVC with a chlori nated PVC containing 67 wt % Cl (CPVC67). Each binary DOP/chlorinated polymer pair is miscible whereas PVC/CPE48 and PVC/CPVC67 blends are i mmiscible. DOP/CPE48/PVC and DOP/PVC/CPVC67 ternary blends containing, respectively, more than 55 and 20% DOP exhibit a single glass transit ion temperature (T(g)). The spinodal between the one-T(g) zone and the two-T(g) zone is symmetrical in the two cases. At high DOP concentrat ions, a quantitative analysis of the results leads to the conclusion o f the presence of a true ternary phase. At low DOP concentrations wher e two T(g)s are observed, the DOP is distributed equally between the t wo chlorinated polymers forming, in the DOP/CPE48/PVC case for instanc e, two binary DOP/CPE48 and DOP/PVC phases. The broad immiscibility zo ne observed in the DOP/CPE48/PVC ternary blend as compared to the DOP/ PVC/CPVC67 blend appears to be mainly caused by the high molecular wei ght of CPE48, as compared with PVC and CPVC67. (C) 1994 John Wiley & S ons, Inc.