INFLUENCE OF GAMMA RADIATION ON EPDM COMPOUNDS PROPERTIES FOR USE IN NUCLEAR PLANTS

Various types of EPDM rubbers are used in radiation areas such as coating materials for wire and electrical cables, due to their higher resistance to environmental effects when compared to other types of rubbers. Properties set for EPDM rubbers that include degradation and good chemical resistance, besides excellent electrical properties have been stimulating the application of this elastomer for low and medium voltage (up to 35 kV). EPDM rubber is classified as radiation-resistant, because EPDM structure includes in its principal chain totally saturated bonds, and consequently is able to absorb more energy without cracking polymeric chain. The purpose of this work was studying radiation influence on rubbers compounds used in wires and electrical cables installed in Nuclear Plants. There were prepared EPDM compounds samples, further subjected to gamma radiation at doses: 25 kGy, 50 kGy, 75 kGy, 100 kGy and 200 kGy. Mechanicals properties and swelling properties were assessed in non-irradiated and irradiated samples at different doses. It was observed a reduction in tensile at break values, proportional to the dose applied and pointing toward a raise in material fragility. This reduction is more severe for doses higher than 100 kGy, indicating the predominance of chain-scission with further polymer degradation.