The effect of gamma irradiation on the electrical and mechanical properties of bismuth carbonate-silicone rubber

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Silicone rubber samples loaded with three different concentrations of bismuth carbonate 30, 35, and 40 wt % are prepared and mixed by the compressive method. The effect of gamma irradiation on both mechanical and electrical properties are investigated. The obtained results showed that the hardness of rubber samples is increased with increasing both the bismuth concentration and gamma irradiation dose. At the same time, the Young modulus, the tensile strength, and fracture strain (elongation at break) are decreased. Decreasing the tensile strength with the gamma irradiation dose can be attributed to the increase of the degradation process resulting in the scission of bonds in the rubber chains. Although bismuth carbonate filler improves the mechanical properties of the aging resistance to gamma irradiation, at higher concentrations for each, a degradation process of rubber chains is more predominant than crosslinking. Also, increasing the gamma irradiation dose decreases the samples’ electrical resistivity and increases their electrical conductivity. Knowing the variation of the mechanical and electrical properties of the irradiated bismuth silicone rubber composite will assist in identifying the suitability of its use in several applications, such as radiation sterilization of the silicone rubber for medical usage.