Physical and chemical changes induced by 70 MeV carbon ions in polyvinylidene difluoride (PVDF) polymer

Physical and chemical changes induced by 70 MeV carbon ions (12C5+) have been investigated in bulk polyvinylidene fluoride (PVDF) polymer. The induced changes have been studied with respect to their optical, chemical and structural response using UV-visible, FTIR and XRD techniques. The ion fluences ranging from 2.5x1011 to 9x1013 ions cm-2 have been used to study the irradiation effects. It has been observed that at the fluence of 9x1013 ions cm-2 the PVDF sample became brittle and practically it was not possible to handle it for any further measurements. The recorded UV-visible spectra show that the optical absorption increases with increasing fluence, indicating maximum absorption at 200 nm. An interesting feature of UV-visible spectra is that dips change into peaks and vice versa with increase of fluence. In the FTIR spectra, development of new peaks at 1714 and 3692 cm-1 along with disappearance of peaks at 2363 and 3025 cm-1 and shifting of peak at 2984-2974 cm-1 have been observed due to high energy irradiation, indicating the chemical changes induced by 12C5+. The diffraction pattern of PVDF indicates that this polymer is semi-crystalline in nature; a large decrease in the diffraction intensity indicates decrease in crystallinity. Increase in crystallite size has also been observed due to heavy ion irradiation