Thermal degradation of elastomeric vulcanized poly(ethylene-co-vinyl acetate) (EVM): Chemical and kinetic investigations

The thermal degradation of vulcanized elastomeric poly(ethylene-co-vinyl acetate) (EVM) in inert and oxidative conditions was investigated. Based on the characterization of both condensed and gas phases during the thermal degradation it was possible to propose a reaction scheme of the EVM degradation. In addition, the determination of the kinetic parameters completed the chemical investigations. The thermo-oxidation of vulcanized EVM occurs in five steps, including the cleavage of some cross-linking bonds, the catalytic deacetylation forming polyenes and a charring step, followed by the decomposition and oxidation of the char. It appeared that the curing, and thus the cross-linking nodes, enhances the thermal stability of EVM by favouring the charring. On the other hand the pyrolysis of the polymer is quite not influenced by the vulcanization.