Thermogravimetric Kinetics of Polystyrene Degradation over BaO

The polystyrene (PS) degradation and its catalytic degradation by adding BaO in it as catalyst (PS-BaO) were studied by thermogravimetry, and the degradation activation energies of PS and PS-BaO were obtained respectively by Vyazovkin model-free kinetic method. For the whole degradation process, the degradation activation energy of PS was found to be 210 kJ·mol-1 and that of PS-BaO to be 200 kJ·mol-1. Especially, at the beginning of the degradation, the degradation activation energy of PS is 250 kJ·mol-1 and that of PS-BaO is 200 kJ·mol-1, it indicates that the presence of BaO changes the initiating mechanism of PS degradation and the BaO is an effective catalyst for PS degradation. According to model-free kinetic method, the curves of isothermal conversion via time of PS-BaO degraded under different temperatures were obtained too; they can be used to estimate the degradation time or temperature needed for a given PS conversion degree required and can provide valuable guide for practical application thereby.