Physico-chemical modifications induced by 70 MeV carbon ions in alpha phased polyvinylidene fluoride (-PVDF) polymer

Abstract

In the present paper, the physico-chemical changes induced by 70 MeV carbon ions (¹²C⁺⁵) have been investigated in PVDF using UV-Visible, FTIR, XRD and HFIA techniques. The induced changes have been studied with respect to their optical, chemical, structural and electrical response. The polymer samples have been irradiated in the ion fluence ranging from 110¹¹ to 310¹² ions cm^-2. The UV-visible spectra show that the optical absorption increases with increasing ion fluence. Two new dips at 482 nm and 654 nm were appeared in the irradiated sample which may be due to the fluorinated defects created due to irradiation. In the FTIR spectra, it was found that transmittance intensity decreases with increasing ion fluence in the range 1500-4000 cm^-1. The diffraction pattern of PVDF indicates that crystallinity decreases with increasing ion fluence but the crystallite size is found to increase due to carbon ion irradiation. The variation of dielectric constant and dielectric loss for virgin and irradiated films have been studied in the frequency range 10 mHz-10 MHz at ambient temperature. There is an exponential increase in ac conductivity with increasing frequency and the effect of irradiation is significant at higher fluence. The dielectric constant and dielectric loss changed significantly due to ion beam irradiation, meanwhile the frequency exponents decreased with increasing ion fluence. It was found that dielectric response in both virgin as well as irradiated samples obey the Jonscher’s power law.