Kinetic study of the thermal and thermo-oxidative degradations of aromatic poly(ether sulfone) random copolymers bearing pendant carboxyl groups

A series of poly(ether sulfone) random copolymers at various loading of diphenolic acid (DPA) units were synthesized and subjected to a comprehensive kinetics degradation study to assess their thermal behaviour. Poly(ether sulfones) were synthesized from different amounts of 4,4′dihydroxydiphenylsulfone, DPA and stoichiometric quantity of 4,4′-dichlorodiphenyl sulfone by nucleophilic aromatic displacement. The apparent activation energy ( E a ) of degradation for the prepared compounds was determined by using a kinetics literature method, discussed and compared with each other and with those obtained in the past for similar polymers. The comprehensive thermal stability evaluation was completed with the assessment of the initial decomposition temperature of the prepared copolymer, showing a good thermal performance but, in the meantime, suggesting caution as regards the percentage of functionalization setting the limit beyond which a deterioration of the physical properties of the copolymers at 30% of pendant carboxylic acid groups was observed.