TEMPERATURE EFFECT ON RADIATION-INDUCED REACTIONS IN ETHYLENE AND TETRAFLUOROETHYLENE COPOLYMER (ETFE)

Ethylene and tetrafluoroethylene copolymer (ETFE) was irradiated by ga mma-rays or electron beam (EB) under oxygen-free atmosphere at various temperatures ranging from 77 to 573 K. Mechanical and thermal propert ies, and absorption spectra of the irradiated ETFEs were measured. The mechanical properties of the film have been observed to change by irr adiation. The modulus and yield strength increase with increasing dose , and these phenomena are clearly distinguished above the melting temp erature of ETFE (533 K). Heat of crystallization changes drastically a s a function of irradiation dose around the melting temperature, compa red with other temperatures. The absorption band around 250 nm of irra diated ETFE shifts to a longer wavelength region with increase of irra diation temperature. Therefore, it was concluded from those experiment al results mentioned above that crosslinking takes place and conjugate d double bonds formation proceeds in a wide range of irradiation tempe ratures. Those reactions are enhanced by increasing temperature. The h omogeneous crosslinking takes place in the molten stare, while the het erogeneous crosslinking does in the crystalline solid state. (C) 1997 Elsevier Science Ltd. All rights reserved.