The pyrolysis of polyethylene terephthalate (PET) is a well-known process for producing high fuel value. This paper aims to study the kinetics of PET pyrolysis reactions at 4 different heating rates (2, 5, 10, and 20 K min-1) using thermogravimetric analysis (TGA) data. TGA data show only one kinetic reaction within the temperature ranges of 650 to 750 K. Five different model-free models, namely, the Freidman (FR), Flynn-Wall-Qzawa (FWO), Kissinger-Akahira-Sunose (KAS), Starink (STK), and distributed activation energy model (DAEM), were fitted to the experimental data to obtain the activation energy (Ea) and the pre-exponential factor (A0) of the reaction kinetics. The Coats-Redfern (CR) model equation was fitted with the help of master plot (Criado's) to identify the most convenient reaction mechanism for this system. Ea's values were determined by the application of the five aforementioned models and were found to possess an average value of 212 kJ mol-1. The mechanism of PET pyrolysis reaction was best described by first-order reaction kinetics; this was confirmed by the compensation. Further thermodynamic parameter analysis indicated that the reaction was endothermic in nature.
Keywords: kinetics; polyethylene terephthalate (PET); pyrolysis; thermodynamic parameters; thermogravimetric analysis (TGA).