Thermal degradation of silane crosslinked unplasticized PVC

The thermal decomposition behaviour of rigid PVC, crosslinked using bis(γ-trimethoxysilylpropyl)amine as crosslinking agent has been studied. Different thermal stabilizers (tin and lead based) have been used with different crosslinking agent concentrations, and the influence of these factors on the decomposition behaviour in inert atmosphere studied. Results obtained have shown that the main effect of aminosilane is an advance of the first stage of the PVC degradation (i.e. the dehydrochlorination process). Moreover, samples with different concentrations of silane, and at different stages of their processing (i.e. after milling, pressing, crosslinking) have also been used in order to elucidate the influence of these factors on their thermal behaviour. A quantitative kinetic model has been developed and the corresponding kinetic constants have been obtained by modelling the experimental thermogravimetric data. The kinetic parameters obtained have revealed a reduction in the apparent activation energy of the hydrogen chloride loss process, which has shown to be markedly dependent on the thermal stabilizer used.