The influence of chain ends on the thermal and rheological properties of some 40/60 PES/PEES copolymers

Four random, differently ended (Cl, NH2, OH, and COO2), polyethersulfone/polyetherethersulfone (PES/ PEES) copolymers were studied to investigate the influence of chain ends on thermal and rheological behaviors. The number average molar mass (Mn 9500 gmol21) and the PES/PEES ratio (40/60) of all copolymers investigated were checked by 1H NMR spectra. Thermal degradations were carried out in the scanning mode and initial decomposition temperatures (Ti) and activation energy values of degradation (Ea) were obtained. Glass transition temperature (Tg) was determined by differential scanning calorimetry and complex viscosity (g*) by rheological measurements in isothermal heating conditions (T ¼ 2708C). All parameters determined were largely affected by copolymer chain ends and decreased according to the same order, OH > NH2 > Cl > COO2. The results were discussed and interpreted.