Study on Positron Annihilation Characteristics with Some Physical Properties of Polyvinyl Alcohol (PVA)/ Polyethylene Glycol (PEG) Composites.

Abstract

Reduced graphene oxide (RGO) doped polyvinyl alcohol/ polyethylene glycol (PVA/PEG) films were prepared by solution casting technique and exposed to 100 kGy gamma radiation. The structural modifications in the samples before and after irradiation were studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry DSC. The free volume holes (V_f ) determined from the ortho-positronium (o-Ps) lifetime (τ_3) measured by the positron annihilation lifetime spectroscopy (PALS) is found to decrease from (84.52 to 67.24 Å^3) and from (85.67 to 78.21 Å^3) for nonirradiated and irradiated samples respectively with increasing the nanoscale RGO filler volume fraction in the range from (0 to 0.265) into the polymer matrix. The resulting decrease of the free volume holes size due to this incorporation could be explained by both the formation of hydrogen-bonding and crosslinking between RGO and PVA/PEG blend as confirmed by scanning electron microscope (SEM) images, XRD and FTIR measurements. A decrease is also observed in the concentration of free volumes (F_r) for both nonirradiated and irradiated samples.