Optical investigation of the effect of gamma radiation on synthesized PVA/CS/CMC blend membranes

In the present investigation, polyvinyl-alcohol, chitosan, and carboxymethyl cellulose (PVA, CS and CMC) polymers were blended applying the casting approach. Samples from the prepared PVA/CS/CMC blend membranes were exposed to gamma (γ) rays at doses at levels between 5 Gy and 40 kGy. The influence of γ-irradiation on the optical characterization of the blend membranes was investigated applying UV-Vis spectroscopy. Also, the color modifications among the irradiated membrane and the pristine were evaluated by means of the CIE color modification methodology. Results indicated that the optical bandgaps decreased with increasing γ-ray dose up to 40 kGy, while the Urbach energy displayed an opposite behavior. This is attributed to the domination of crosslinks among the blend chains. Furthermore, the type of microelectronic transitions was determined for the blend membranes using the optical dielectric loss function which were appeared to be direct allowed transitions. In addition, the impact of γ radiation on the blend membrane's optical conductivity, refractive indices, extinction coefficients, absorbance and optical dielectric loss were studied. Furthermore, the changes in color among the pristine and irradiated samples were determined. The pristine membrane was colorless. When exposed to γ irradiation, it displayed permanent color changes.