Dynamic TG studies on the thermal decomposition of PVC plastisols

The kinetics involved in the thermal decomposition of PVC plastisols and unmixed PVC-plasticizer systems were compared using dynamic thermogravimetric (TG) analysis. Three kinetic models were tested. In all cases thermograms obtained at different heating rates were simultaneously correlated with the same constants. Significant differences indicative of PVC-plasticizer (DOP) interactions were found between the plastisol systems and the unmixed PVC-plasticizer systems. When the plasticizer is in the paste, its evolution suffers a delay with respect to the case when PVC and plasticizer were separated. The activation energy for DOP evolution takes the value 109.2 in the first case and 81.6 KJ/mol in the second case. PVC decomposition takes place at lower temperatures when it is in the paste, and its activation energy is 177.4 and 206.7 KJ/mol for PVC in plastisol and unmixed PVC, respectively.