Pyrolysis kinetics of γ-irradiated polypropylene

The influence of irradiation on the thermal degradation of polypropylene (PP) was studied by performing thermogravimetric analysis at three constant heating rates and at a constant temperature. The results of the weight-loss thermogram and the rate of conversion during the degradation suggested that a small irradiation dose was enough to significantly enhance the pyrolysis activity. Kinetic parameters [k(0)(E) and f(E)] of the decomposition reaction were estimated by applying a simple distributed activation energy model (DAEM) proposed by Miura and Maki (Miura K, Maki T. Energy Fuels 1998,12:864). The estimated kinetic parameters showed unexpected dependence on the irradiation dose, which was explained partly based on the known mechanism of polymer degradation. The results suggested that the presented analysis method is sensitive enough to extract the change in rate parameters among slightly modified PPs. The validity of the estimated parameters was verified by comparing the predicted weight-loss thermograms with the experimental data obtained at different dynamic heating rates. (C) 2001 Elsevier Science Ltd. All rights reserved.