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

The effects of irradiation on poly(ethylene terephthalate) have been i nvestigated by differential scanning calorimetry. On irradiation, defe ct structures are formed which serve to reduce or prevent molecular re organization. Irradiation of amorphous specimens shows that no crystal lization occurs above an absorbed dose of similar to 30 MGy. The respo nse of semicrystalline samples is dominated by radiation-induced cryst al destruction; the lamellae have been extensively modified by 30 MGy and little crystallinity remains above 66 MGy. As a consequence of the se 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 resis tance of crystalline conformations in PEEK is indeed highly unusual.