Thermal and Thermo-oxidative Degradations of Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)/Copoly(aryl ether sulfone) P(ESES-co-EES) Block Copolymers: a Kinetic Study

The thermal degradation of a series of three novel ABA block copolymers of different molar mass (Mn), were the block A is a poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) while the block B is a random copoly(aryl ether sulfone) P(ESES-co-EES), was studied in both inert (flowing nitrogen) and oxidative (static air) atmospheres, in order to investigate the effects of Mn of the central block on the thermal stability. Copolymers were synthesized with a two steps method: in the first stage a linking molecule is selectively attached as end group to the P(ESES-co-EES) which reacts in the second step with the phenolic hydroxyl group of PPO. Degradations were carried out into a thermobalance, in the scanning mode, at various heating rates, and the characteristic parameters of thermal stability, namely initial decomposition temperature (Ti) and the activation energy (Ea) of degradation, of the various copolymers were determined.Both Ti and degradation Ea values increased exponentially as a function of Mn of copolymers. The results were discussed and interpreted.