Electrical conduction and dielectric properties of γ-irradiated EPR

We have measured the charging and discharging currents of γ-irradiated EPR without filler, and obtained the electrical conductivity and the dielectric parameters, α, τ₀ and ε_r0-ε_r∞, for Cole-Cole´s circular arc law. We found the dielectric relaxation in the region of ultralow-frequency at room temperature. The parameter of the polarization, α, and ε_r0-ε_r∞ , are almost independent of dose, but τ₀ decreases with dose. The relaxation time had nearly the same activation energy as that for the electrical conductivity, and was independent of electrode materials. Therefore, we consider that this polarization is caused by a bulk interfacial polarization. It can be thought that the comparatively conductive regions are generated inhomogeneously in rubber by the γ-irradiation, giving rise to an interfacial polarization inside the rubber