Thermal and rheological behaviour of some random aromatic polyethersulfone/polyetherethersulfone copolymers

The thermal and rheological behaviour of seven random Cl-ended aromatic PES/PEES copolymers (M approximate to 9500 g mol(-1)), at various PES/PEES repeating unit ratios, was studied. The glass transition temperatures (T-g), determined by DSC experiments, showed a dependence on copolymer composition significantly different from the ideal linear behaviour expected on the basis of Fox equation. Degradations were carried out in the scanning mode, under flowing nitrogen, in the temperature range 35-650 degrees C and a single degradation stage was observed for all copolymers. The initial decomposition temperatures (T-i) and the half decomposition temperatures (T-1/2) were directly determined by TG curves, while the apparent activation energies of degradation (E-a) were obtained by the Kissinger method. In addition, the complex viscosity (eta *) of molten copolymers was determined in experimental conditions of linear viscoelasticity. T-i, T-1/2, E-a, and eta * values were depending on copolymer composition, showing a trend similar to that of T-g values. The results obtained were discussed and interpreted. (c) 2005 Elsevier Ltd. All rights reserved.