Influence of High-Energy Ion Irradiation on the Structural, Optical, and Chemical Properties of Polytetrafluoroethylene.

ABSTRACT Polytetrafluoroethylene (PTFE) polymer samples were irradiated by 50 MeV Li3+ ion beams to the fluences of 1 × 1010, 1 × 1011, and 1 × 1012 ions/cm2. The structural, optical, and chemical properties were studied by X-ray diffraction (XRD), UV-visible (UV-vis) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy, respectively. The XRD analyses showed amorphization of the polymer sample at fluences of 1 × 1010 and 1 × 1011 ions/cm2. Crystallite size (calculated by applying the Scherrer formula) decreased for irradiated samples at fluences of 1 × 1010 and 1 × 1011 ions/cm2. The other factors like microstrain (ε), dislocation density (δ), and distortion parameters ( g) showed variations at these fluences. However, there was no change in the interchain separation ( R) and interplanar distance ( d) for all irradiated samples. UV-vis showed a shift of the absorption edge of irradiated samples towards the visible region. The band gap energy ( Eg) was calculated using Tauc's relation, and its value decreased with an increase of ion fluence for all irradiated samples. The number of carbon atoms per conjugation length ( N) increased for the irradiated samples. The FTIR results revealed the liberation of CF2 groups and the appearance of some new bands after irradiation. [ABSTRACT FROM AUTHOR]