PALS and physico-chemical study of swift heavy ions and gamma radiation irradiated polyamide nylon 66 polymer

Abstract

Polyamide nylon 66 (PA-66) polymer samples after being irradiated with 100 MeV O7+ ions and gamma radiation were studied for modifications in free volume properties by using positron annihilation lifetime spectroscopy (PALS) technique. The results obtained from PALS experiment were analysed in terms of hole radius, available free volume and fractional free volume. Both, ion irradiation as well as gamma exposure showed modifications in the size of available free volume and fractional free volume but the effectiveness of gamma radiation exposure was more pronounced than that of ion irradiation. The modifications produced in optical, structural and chemical properties of the PA-66 samples were studied by UV–visible (UV–vis) spectroscopy, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy respectively. UV–vis studies showed a shift in absorption edge towards the visible region and a decrease in band gap energy (Eg). An increase in the crystalline nature of the polymer at higher fluence as a result of decrease in the peak width of XRD patterns was observed. The FTIR studies showed insignificant modifications in the chemical structure of irradiated polymer samples. Increase in surface roughness and cracks were observed in SEM results of ion and gamma exposed samples respectively.