Effect of homogeneity on the thermal degradation of poly(vinyl chloride)/poly (α-methylstyrene-acrylonitrile-methylmethacrylate) blends

Abstract

The thermal degradation of homogeneous and heterogeneous poly(vinyl chloride)/poly(α-methylstyrene-acrylonitrile-methylmethacrylate) (PVC/ MS-AN) blends were investigated by means of dynamic thermogravimetry. The blends were prepared by precipitation from solution in a common solvent (homogeneous PVC/MS-AN-MMA blend) and by pressing the mixture of solid polymers in a cold hydraulic press (heterogeneous PVC/MS-AN-MMA blend). From the thermogravimetric curves and by determining the kinetic parameters of thermal degradation, the effect of the degradation products of one polymer on the degradation process in the other polymer in the blend was established. The homogeneous compositions show no particular differences in characteristics of degradation at high temperatures when compared with the heterogeneous compositions of either precipitated or pressed samples. This effect is due to the fact that the phase diagram of PVC/MS-AN-MMA blend shows an upper critical solution temperature. This means that all of the blend systems, precipitated and pressed, are miscible at temperatures above the critical solution temperature.