Thermal degradation kinetics of poly(aryl ether sulfone 1,3,5-triazine)s containing phthalazinone moieties

Thermal degradation of phthalazinone-based poly(aryl ether sulfone 1,3,5-triazine) copolymers (PPESTs) has been investigated under nitrogen flow in dynamic heating conditions. Model-free kinetic approaches were applied to data for decomposition processes of PPESTs with different molecular structure. The activation energy was calculated as a function of the degradation extent by using Kissinger–Akahira–Sunose and Vyazovkin method. The effect of polymer composition and structure on the characteristic temperatures and kinetic parameters of thermal degradation was also investigated. The replacement of sulfone by 1,3,5-triazine in polymer main chain significantly increases initial decomposition temperature and Ea, and its stabilizing effect may be explained by the existence of two-stage decomposition process that suppresses unzipping of the copolymers. This assumption is supported by the experimental fact that the complete replacement of sulfone by 1,3,5-triazine increases the initial decomposition temperature by 31 °C and Ea by at least 57 kJ/mol according to Vyazovkin method.