Temperature effect on radiation induced reactions in ethylene and tetrafluoroethylene copolymer (ETFE)

Ethylene and tetrafluoroethylene copolymer (ETFE) was irradiated by gamma-rays or electron beam (EB) under oxygen-free atmosphere at various temperatures ranging from 77 to 573 K. Mechanical and thermal properties, and absorption spectra of the irradiated ETFEs were measured. The mechanical properties of the film have been observed to change by irradiation. The modulus and yield strength increase with increasing dose, and these phenomena are clearly distinguished above the melting temperature of ETFE (533 K). Heat of crystallization changes drastically as a function of irradiation dose around the melting temperature, compared with other temperatures. The absorption band around 250 nm of irradiated ETFE shifts to a longer wavelength region with increase of irradiation temperature. Therefore, it was concluded from those experimental results mentioned above that crosslinking takes place and conjugated double bonds formation proceeds in a wide range of irradiation temperatures. Those reactions are enhanced by increasing temperature. The homogeneous crosslinking takes place in the molten stare, while the heterogeneous crosslinking does in the crystalline solid state. (C) 1997 Elsevier Science Ltd. All rights reserved.