Correction and validation of the Master-plots method for the thermal cracking kinetic mechanism of solvent-swollen polypropylene

Abstract

The current research on the pretreatment of polypropylene before thermal cracking and the precise kinetic mechanism function is insufficient. In this study, the thermal cracking characteristics of solvent-swollen polypropylene in toluene, benzene, and tetrahydrofuran were investigated using a thermogravimetric analyzer. A kinetic study of the samples was conducted employing iso-conversional methods, the kinetic compensation effect, the Master-plots method, and the Popescu method. The results demonstrated that the solvent swelling treatment facilitated the thermal cracking of polypropylene at lower temperatures. The average apparent activation energy values of the samples obtained by the Starink (STK) method ranged from 237.66 to 257.98kJ/mol. The kinetic mechanism function of polypropylene at high conversion differs from that at low conversion. For PP-MB, the kinetic mechanism function follows a three-dimensional diffusion model (D5) in the 0.1–0.5 conversion range and lies between a one-dimensional diffusion model (D1) and a two-dimensional diffusion-cylindrical symmetry model (D2) in the 0.5–0.9 conversion range.