Chemical stability of ethylene-tetra-fluoro-ethylene irradiated by electron beam

The ethylene tetra-fluoro-ethylene-copolymer (ETFE) sheets were irradiated by electron beam at low dose rate of 20 kGy/h in the air. The absorbed dose range was 0-1600 kGy. The samples irradiated with different absorbed doses were tested and characterized by mechanical properties, infrared spectroscopy, Raman spectroscopy and DSC (differential scanning calorimetry). The results showed that elongation and tensile strength decreased slowly within the dose range of 0-200 kGy, however, it dropped sharply when the dose was more than 400 kGy. The results of infrared spectra showed that the carbonyl index increased with absorbed dose, which indicated that the surface of sample was severely oxidized during irradiation. The results of Raman spectroscopy analysis showed that low dose rate irradiation of electron beam disrupted ETFE molecular chain. DSC test results showed that, with the increasing of the absorbed dose of ETFE, crystallinity and melting point decreased gradually; the crystallinity decreased from 43.2% to 12.6%; and the melting point decreased from 261.3 ℃ to 233.3 ℃. (authors)