Molecular Structure Evaluation of Bulk Polytetrafluoroethylene Modified by X-ray Irradiation

Bulk polytetrafluoroethylene (PTFE) can be modified via X-ray irradiation. The X-rays, which have a continuous spectrum from 3 to 8 keV, penetrate deep into the PTFE substrate and induce a scission in the polymer main chain, -C-C-. In previous research, the optical properties of a PTFE sample were successfully modified; UV and visible transmittance drastically increased in the irradiated area of the substrates. In this study, the characterization of the chemical structure of the samples was carried out using Raman and FTIR spectroscopies. The results suggest the formation of CF3 branches, which are not intrinsic to PTFE. In previous works, it has been reported that a similar modification was achieved using electron beam irradiation of several-MeV in molten PTFE, or by α-irradiation onto a PTFE substrate, where the modification depth was of tens of micrometers. On the contrary, we have succeeded the similar modification by using the X-rays.