Leakage current suppression and resistance to tracking and erosion of HTV silicone rubber with added silicone plasticizer

The present study evaluated the leakage current suppression and the resistance to tracking and erosion of high-temperature vulcanized silicone rubbers (HTV-SIRs) containing different levels of silicone plasticizer. Slab HTV-SIRs unfilled and filled with alumina trihydrate (ATH, 50 wt%) and with added linear silicone plasticizer (0-6.0 wt%), which was terminated with hydroxyl groups and of which repetition number was 13-18, were tested. Evaluation using the IEC 60587 inclined-plane method indicated that the plasticizer had no influence on the tracking and erosion behavior. Salt-fog test results indicated that a higher level of plasticizer in the ATH-filled HTV-SIR showed smaller leakage current. Gas chromatography and mass spectrometry suggested that the enhanced suppression of the leakage current for ATH-filled HTV-SIR can be attributed to migration of the linear silicone plasticizer onto the surface contaminants. It was concluded that the addition of silicone plasticizer is useful for improving the leakage current suppression ability of HTV-SIR without reducing its tracking and erosion resistance in the above laboratory tests