A Comparative Analysis of the Electrical Properties of Silicone Rubber Composites with Graphene and Unwashed Magnetite

Three elastomer samples were prepared using GS530SP01K1 silicone rubber (ProChima). The samples included pure silicone rubber (SR), a silicone rubber-graphene composite (SR-GR), and a silicone rubber-magnetite composite (SR-Fe₃O₄). The magnetite was synthesized via chemical precipitation but was not washed to remove residual ions. The dielectric response and electrical conductivity of these samples were analyzed across a frequency range of 500 Hz to 2 MHz. The analysis of the complex dielectric permittivity and Cole-Cole plots indicated a mixed dielectric response, combining dipolar behavior and charge carrier hopping. Despite this mixed response, electrical conductivity followed Jonscher's power law, with the exponent values (0.5 < n < 0.9) confirming the dominance of electron hopping over dipolar behavior in SR-GR and SR-Fe₃O₄ samples. The SR-Fe₃O₄ sample demonstrated higher dielectric permittivity and electrical conductivity than SR-GR, even though graphene is inherently more conductive than magnetite. This discrepancy is likely due to the presence of residual ions on the magnetite surface from the chemical precipitation process as the magnetite was only decanted and dried without washing. These findings suggest that the ionic residue significantly influences the dielectric and conductive properties of the composite.