Kinetics and thermodynamics of non-isothermal pyrolysis of polypropylene grocery bags

Non-isothermal degradation of polypropylene grocery bags was investigated using thermogravimetric instrument in temperature range of 30 °C – 900 °C. One differential and four integral approaches were used to estimate kinetic parameters. Average apparent activation energy (Eα) and pre-exponential factor (k0) determined by five methods were: 147.59—158.27 kJ/mol and 2.042⨯1012—9.09⨯108 min−1, respectively. Average values of change in Gibbs free energy, change in entropy, and change in enthalpy at heating rate 10 K/min were 207.75 kJ/mol, − 0.09282 kJ/mol K, and 141.73 kJ/mol, respectively, calculated by Kissinger–Akahira–Sunose method. Master plots based on the integral form of kinetic data (MPI), Criado’s master plots method (CMP) and fitting models were used to find the reaction mechanism of pyrolysis of polypropylene grocery bags. Irrespective of heating rates, master plots based on the integral form revealed that experimental data fall between F0 and F3 of theoretical plots, thus, Fn model explains reaction mechanism; while Criado’s master plots displayed that pyrolysis data was followed by a multistep reaction. On the other hand, fitting models approach describe that this reaction is described by a diffusion control model.