Effect of gamma irradiation on the thermal stability and morphology of nanoclay-reinforced PVC composites for cables utilized in nuclear fields

This study investigates the effect of nanoclay addition and gamma irradiation on the thermal, structural, and morphological properties of polyvinyl chloride (PVC) composites for potential use in electrical cable insulation under radiation environments. Initially, PVC films were prepared with varying nanoclay concentrations (0, 5, 10, 20, 25, and 50 wt%) using a solution-casting method. Fourier-transform infrared (FTIR) spectroscopy confirmed physical dispersion with minimal chemical interaction. UV–Vis spectroscopy revealed enhanced UV absorption due to the light-scattering properties of nanoclay, while X-ray diffraction (XRD) indicated increased crystallinity, with partial exfoliation observed at 50 wt% nanoclay. Differential scanning calorimetry (DSC) demonstrated that nanoclay incorporation modifies the thermal degradation pathway and alters the thermal behavior of PVC, with higher loadings exhibiting delayed decomposition and altered glass transition behaviour. In a complementary phase, a PVC/nanoclay (80/20 wt%) nanocomposite was subjected to gamma irradiation using a 60 Co source at doses of 0, 25, 50, 100, 150, and 200 kGy. Thermogravimetric analysis (TGA) revealed a pronounced dose-dependent behaviour, where thermal stability improved at intermediate irradiation doses (100–150 kGy), as evidenced by increased decomposition temperatures and higher residual mass. This improvement may be associated with radiation-induced structural changes; however, crosslinking was not directly verified in this study. In contrast, increasing the irradiation dose to 200 kGy resulted in reduced thermal stability, consistent with increased radiation-induced degradation. Scanning electron microscopy (SEM) further supported these findings, revealing improved structural compactness and interfacial homogeneity at intermediate doses, followed by the formation of microcracks and structural degradation at higher doses. These findings highlight nanoclay-reinforced PVC composites as potential candidates for further investigation in radiation-exposed cable-insulation applications, where thermal stability and radiation resistance are critical. However, the observed thermal behavior does not directly establish flame-retardant performance or electrical insulation properties, and further application-specific testing is required to assess their suitability for nuclear cable applications.