An evaluation of the thermal degradation kinetics of novel melt processed PET–hemp fiber composites

This work reports the thermal degradation kinetics of five formulations of polyethylene terephthalate (PET) reinforced with 1, 5, 10, 15, and 20 % hemp fibers based on thermogravimetric investigations. Two consecutive degradation steps were observed between 573 and 773 K. Moreover, their kinetic triplets were determined by nonlinear curve fitting methods, with the Sestak–Berggren and the truncated Sestak–Berggren models, respectively. The resulting kinetic parameters varied with the fiber’s concentration in the following ranges: 1.8 ≤ A ≤ 5, 2.25 ≤ n ≤ 3.17, 7.05 ≤ m ≤ 12.74, and −2.21 ≤ p ≤ −1 for the first step; and 1.76 ≤ A ≤ 10, 1.37 ≤ n ≤ 2.49, and 0.77 ≤ m ≤ 2.35 for the second. This work further confirms the thermal stability of PET–hemp fiber composites and provides key information for the reaction mechanism, a crucial developmental step for bio-composite materials with high-melting thermoplastic matrices.