Short noteOn the degradation kinetics of poly(ethylene terephthalate) (PET)/poly(methyl methacrylate) (PMMA) blends in dynamic thermogravimetry

A thermal degradation model was developed for blends of Poly(ethylene terephthalate) (PET)/Poly(methyl methacrylate) (PMMA) subjected to non-isothermal (dynamic) thermogravimetry at four heating rates (5, 10, 15 and 20 °C/min). The model developed enabled the assessment of pre-exponential factor (A) and apparent activation energy (Ea) for each polymer individually in the blend after developing a mathematical expression based on an integral solution, which was related to both polymer fractions and their blending characteristics in the form of kinetic parameters. The unique approach presented in this study showed that the apparent activation energy of PET (Ea1) in the blend (240-270 kJ/mol) is always higher than PMMA's apparent activation energy (Ea2, 140-170 kJ/mol), which is attributed to the degradation mechanism of the blend and the latter being of a lower melting point hence degrading faster. It was also observed that the activation energy of both polymers increased with PET composition and decreased with higher heating rates, which can be attributed to PET acting as an inhibitor to PMMA in the blends.