The effect of some fillers on PVC degradation

The HCl scavenging effect of particulate fillers such as Red Mud (RM), CaCO3 and dolomite on the thermal degradation of PVC was investigated by thermogravimetry/mass spectrometry (TG/MS). It was found that, in the presence of carbonates, the peak temperature (Tmax) of dehydrochlorination was shifted to a higher temperature and the rate of mass loss was decreased, while, in the presence of RM, FeCl3 was formed and dehydrochlorination of PVC was accelerated, but the second decomposition step of PVC has been retarded. Benzene formation has been hindered by the acid scavenger additives and retarded by RM, evolution of benzene and other aromatics being shifted to higher temperatures.