Kinetic regularities of polymer network thermal degradation

Abstract

The structures and kinetics of the thermal degradation of three polymer networks have been studied. In the course of the thin polyurethane network degradation, the evolution of the MWD of polymer chains has a nonmonotonous character, but the sample mass decrease is described by the equations for two parallel first-order reactions. Activation parameters are shown to depend on the polymer curing conditions. The kinetics of the dense polymer network (the polymer of dimethacrylic ester of triethylene glycol, the epoxyanhydride polymer) degradation depends on the hardness of the polymer samples: soft polymer samples are degradated following a mechanism of radical-chain depolymerization, while for hard polymer samples the degradation proceeds mainly by a decay of unstable functional groups through a molecular mechanism. The results of an NMR study of molecular mobility during PTGM degradation are explained by the microheterogeneous structure of this polymer. It has been shown that the kinetic regularities of the dense polymer network degradation strongly depend on the presence of inert fillers.