Maximum degradation rates in vinyl polymers

The thermal and thermwxidative degradation of thermoplastic vinyl polymers has been studied extensively. However, there are several features which are either controversial or not understood clearly. From dynamic thermogravimetric (TG) studies in our laboratory we have observed that in thennooxidative degradation, although it starta at lower temperatures compared to thermal degradation, the rate of main degradation (between 20 and 80%) is always higher in the latter case. Such an observation borne out by a few literature TG curves, but no explanation whatsoever is available for this anomaly. In this letter we attempt to carry out a systematic TG study on few vinyl polymers in $N_2$ and $O_2$ to explain this behavior. It may be pointed out that here we deal with an empirical comparison of the overall average degradation data (based on dynamic TG), which do not represent a comparison of the actual degradation rates based on the main chain links of the polymers.