Kinetics of thermal decomposition of expandable polystyrene in different gaseous environments

The characteristics of thermal decomposition of expandable polystyrene (EPS) were studied in various gaseous environments, both oxidizing and non-oxidizing, over a narrow range of heating rates between 5 and 25 K/min using non-isothermal thermogravimetric analysis (TGA). The modified Coats–Redfern technique, a model-independent isoconversional method, was utilized for investigating the decomposition kinetics. Results from kinetic data analysis revealed the difference in reaction mechanism between oxidizing and inert environments. Common to all the environments, the decomposition involves two mechanistic steps, one of them occurring during the initial and mid conversion levels, and the other during the final stages. The only key differences between the oxidizing and inert environments possibly lie in the first mechanistic step as evidenced by the huge difference in the activation energies between them.