The degradation behavior and mechanism of polytetrafluoroethylene under low energy proton irradiation

The degradation behavior and mechanism of polytetrafluoroethylene (PTFE) under low energy protons irradiation was investigated. Optical transmittance and Fourier transformed Infrared spectrometer (FTIR) indicate that there produce two kinds of specific defects during the proton irradiation, leading two optical absorption peaks at about 200 nm and 240-280 nm. The results of X-ray photoelectron spectroscopy (XPS) indicate that there include the processes of defluorination in the first stage and then carbonization in PTFE during proton irradiation. In addition, the results of electron paramagnetic resonant spectra (EPR) demonstrate the evolution of radicals that transform from peroxy radicals (g = 1.9907) to another pyrolytic carbon ones (g = 2.0025). The population evolutions of both kinds of the radicals are investigated and determined dependent on the fluence and also the degradation mechanisms.