Kinetic triplet determination and modified mechanism function construction for thermo-oxidative degradation of waste polyurethane foam using conventional methods and distributed activation energy model method

Abstract

Rapid growth of waste polymers attracts increasing attentions nowadays, and pyrolysis technology is acknowledged as an effective handling way. In this study, waste rigid polyurethane (RPU) was selected to conduct thermogravimetric analysis experiments with four different heating rates. Results showed that the thermo-oxidative degradation of RPU presents a two-main-stage process. Subsequently, thermal degradation kinetics were analyzed by model free, model fitting, and distributed activation energy model (DAEM) fitting methods. Isoconversional methods were used to obtain the apparent activation energy. Pyrolysis kinetic parameters were calculated through selected reaction models by model fitting method. Then the experimental kinetic function was obtained, based on which the proper theoretical reaction models were modified by the accommodation function. The best reaction model from the alternative reconstructed functions was optimized for two steps respectively. Distributed activation energy model was firstly introduced to fit the experimental data of RPU pyrolysis. The results of this study have implications concerning kinetic triplet determination method and reaction models modification, especially guiding to waste polymers pyrolysis kinetics and reaction model construction.