Effects induced by gamma irradiation on free-volumes, mechanical, and thermal properties of flame- and non flame-retardant polyvinylchloride

Flame-retardant polyvinylchloride (FRPVC),typically used in cable insulation and jacketing construction for multi-purpose reactor (MPR) at Atomic Energy Authority of Egypt, as well as carbon-black FRPVC (CB-FRPVC) and nonflame-retardant PVC and CB-PVC materials produced by Egyptian Electrical Cable Company (EECC), have been irradiated up to 160 KGy, at room temperature with a ⁶⁰Co gamma source. Free-volumes and thermal stability of irradiated and nonirradiated PVC samples have been examined using positron annihilation Lifetime Spectroscopy (PALS) and thermogravimetric analysis (TGA). In addition, the mechanical properties: tensile strength and elongation at break were examined. Considerable presence of flame-retardant and carbon black additives in CB-FRPVC sample led to both quenching and inhibition of Ps formation. The mechanical and thermal characterization showed that irradiation of PVC samples up to 80 KGy effectively induced cross-linking to maxima. Higher doses then after results in degradation and thus a decrease in mechanical strength.