Evaluation of influence of mineral oil immersion on dielectrical properties of silicone polymers by Thermal Analysis

In this paper ageing phenomena of polymer insulating materials due to exposure to mineral oil is investigated with focus on dielectrical properties of cable insulations. Silicone specimens were immersed into mineral oils such as gasoline, diesel fuel or motor oil. The dielectric parameters show a significant increase both in permittivity and loss factor. A Simultaneous Thermal Analysis has been performed in order to indicate changes in specimen polymer structure. It could be shown that the specimens with decreased electrical performance suffered from permanent chemical degradation.