Flexible X/Gamma ray shielding composite material of EPDM rubber with bismuth trioxide: Mechanical, thermal investigations and attenuation tests

In this study, the effect of bismuth (III) oxide addition on the mechanical, thermal, rheological and gamma ray attenuation capability of EPDM rubber was extensively investigated. In this context, surface modification with silane was carried out before bismuth oxide particles were incorporated into EPDM. In addition, EPDM samples including 10%, 20% and 30% (w/w) bismuth oxide were irradiated with doses of 25.6, 39 and 57 kGy up to irradiation period of 133 days using a gamma ray source with an initial dose rate of 18.3 Gy/h. Vulcanization parameters of EPDM with 30% bismuth oxide content were evaluated by using both of integral isoconversional method and Kamal-Sourour kinetic model. The activation energy, Ea, was determined as 86.3 kJ/mol. Mechanical tests result of non-irradiated and irradiated EPDM samples with 0 and 30% bismuth trioxide content show that bismuth trioxide content considerably affects the tensile properties. DSC and DMA analysis show that Tg increased with bismuth trioxide addition. The gel-content of the non-irradiated and irradiated EPDM compound was determined with Soxhlet extraction method and obtained result shown the gel-content was changed with the irradiation dose. Moreover, the effect of bismuth trioxide addition on radiation attenuation of EPDM composite was tested. Attenuation ratio from 68.6 to 94% were obtained for samples with different EPDM composite material thickness values.