ON RADIATION EFFECTS IN POLY(ETHYLENE-TEREPHTHALATE) - A COMPARISON WITH POLY(ETHER ETHER KETONE)

The effects of irradiation on poly(ethylene terephthalate) have been investigated by differential scanning calorimetry. On irradiation, defect structures are formed which serve to reduce or prevent molecular reorganization. Irradiation of amorphous specimens shows that no crystallization occurs above an absorbed dose of similar to 30 MGy. The response of semicrystalline samples is dominated by radiation-induced crystal destruction; the lamellae have been extensively modified by 30 MGy and little crystallinity remains above 66 MGy. As a consequence of these factors, controlled irradiation does not constitute a viable means of investigating the melting behaviour of this polymer in the absence of reorganization effects. Comparison with the behaviour of poly(ether ether ketone) (PEEK) leads to the conclusion that the radiation resistance of crystalline conformations in PEEK is indeed highly unusual.