Physico-chemical properties of PVA-Nile blue (C20H20ClN3O) polymer composite structures for γ-ray protection: A comparative γ-ray irradiation studies

Nile blue (NB, (C20H20ClN3O)) dye/polyvinyl alcohol (PVA) polymer composite films were developed by solvent casting technique, and were further exposed to high energy gamma-ray (25-125 kGy) radiation. The influence of dye content and gamma-ray radiation on the optical-spectral behaviour, structural, thermal and mechanical properties of the PVA-NB composite films was discussed. Modifications of the chemical structure of the host matrix - PVA polymer upon dye intercalation and subsequent radiation exposure on these composite structures was confirmed by FTIR analysis. The UV-Vis studies showed a decrease in both band gap (Eg) and Urbach energies (Eu) on the increase of dye concentration while the band gap decreased and the Urbach energy was found to increase on gamma-irradiation (25-125) kGy. These variations could be due to an increase of crystallinity on dye content loading and contrarily to an increase of amorphous nature upon radiation exposure which is supported by XRD results. Further, the thermal behaviour of the pre and post irradiated composite films were studied using DSC. Consequently, these observed modifications in the physico-chemical properties of the pre and post gamma irradiated PVA-(C20H20ClN3O) polymer composite structures impact the mechanical properties. The mechanical studies have revealed an increase in tensile strength and Young's modulus parameters (maximum of 94.688 MPa and 2185.7 MPa for 1 wt%) upon dye content inclusion. However, these parameters decreased (46.396 MPa and 357.76 MPa for 125 kGy) upon radiation-matter interaction. Interestingly, these films could withstand a gamma radiation upto 75 kGy. Therefore, clearly, these observations suggest that the developed polymer composite films are better candidates for the gamma-ray protective kits such as gloves, layers/shields in a variety of industries.