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Abstract Oxidative degradation of rubbers, and the development of oxidized layers at the surfaces, results in increased electrical conductivity. This paper shows that for EPDM rubbers heavily oxidized at 200° C, the DC-conductivity increases more than two orders of magnitude, and the percolation threshold for DC conductivity is decreased below 5 phr carbon black. The effect of oxidation upon the electrical properties is explained as being due to the presence of polar groups, e.g. , carbonyl groups, in between the carbon-black agglomerates which provide shorter distances for the electrons to tunnel through.
Mattson et al. (Fri,) studied this question.