γ-ray effects on PMMA polymeric sheets doped with CdO nano particles

Highlights: • CdO/PMMA sheets have linear chromatic degradation by γ-ray irradiation. • Optical parameters of the CdO/PMMA are correlated with absorbed dose. • γ-ray irradiation affects dielectric and conductivity parameters of polymeric matrix. The present work aimed to study the γ-ray irradiation effects on the physical and chemical behavior of poly methyl methacrylate (PMMA) thin polymeric sheets doped with different concentrations of nano CdO (0.3–1.8 wt. %). Co-precipitation technique was used to prepare CdO nanopowder, while casting-solution method was applied to prepare thin sheets of PMMA/CdO. The XRD analysis of CdO, PMMA and their composites confirmed their formation in pure phase. The particle size distribution of the CdO powder was estimated using TEM imaging and found to be 3–20 nm. According to optical microscopy investigation, good homogeneous distribution was obtained for the CdO powder inside the PMMA sheets. Different sets of the prepared samples were irradiated by γ-ray of ⁶⁰Co source with gradually increasing doses (20–120 kGy). The irradiated samples were analyzed using XRD, FTIR and UV/Vis spectroscopy. Comparative study was done on pristine and irradiated samples at different CdO concentration. The visual appearance of the samples showed chromatic degradation with increasing both CdO concentration and absorbed γ-ray doses. A color map of the irradiated PMMA/CdO samples was presented for monitoring the absorbed dose. The changes in the samples color was attributed to conversion of CdO (reddish brown) to Cd(OH)₂ (clear white) as a result of γ-ray irradiation. The unirradiated samples showed slight decrease in their optical band gap with increasing CdO concentration. Furthermore, a linear correlation between the optical band gap and γ-ray dose was deduced for all the irradiated samples. Electrical permittivity and conductivity of pristine and irradiated samples were measured as a function of frequency at room temperature using LCR bridge. A relative increase in the dielectric constant and AC conductivity of the irradiated samples by about 5–25% was observed for the highest CdO concentration. The electrical parameters of the irradiated samples showed significant changes at high γ-ray dose of 120 kGy. The obtained experimental data were discussed in view of γ-ray interaction with the medium using the suitable models and theories of polarization mechanisms. The results are promising for using the prepared samples as γ-ray dosimeters in addition to enhancement of their electrical properties for various applications.