Radiochemical Ageing of Aromatic Polymers PEEK, PSU and Kapton®

This article deals with degradation mechanism of three aromatic polymers submitted to gamma-rays in air at 60 degrees C. T-g measurements and GPC results indicated that thin samples (thickness lower than 200 gm) undergo mostly chain scission whereas sol gel analysis and rheometric measurements showed that thicker ones undergo mainly crosslinking. Both results are explained by oxygen diffusion control of oxidation resulting in the formation of a superficial oxidized layer experimentally observed by mu ATR InfraRed in which oxidative processes orientate rather to chain scission than crosslinking. Experimental results also allowed discussing relative oxidative stability, sensitivity of T-g to chain scission concentration, and crosslinking mechanism (Y or H).