DEGRADATION OF AROMATIC POLYMERS .4. EFFECT OF TEMPERATURE AND LIGHT-INTENSITY ON THE PHOTODEGRADATION OF POLYETHERSULFONE

Polyethersulfone (PESF) films were photo-degraded in nitrogen at various temperatures below and above the glass transition temperature. Crosslinking and chain scission take place simultaneously, but crosslinking is dominant above 170°C, while chain scission is much more important at room temperature. The fact that the molar ratio of sulfur dioxide produced to the crosslinking density is much less than unity indicated that the photo-degradation of PESF is initiated by cleavage of the CS bond without sulfur dioxide formation. The fact that the quantum yield for crosslinking is independent of the incident intensity suggests that most radicals produced by photolysis add to benzene rings to give cyclohexadienyl radicals which take part in a termination process. © 1990.