Aminopropyltriethoxysilane-modified MXene for remarkably enhancing tracking resistance and flame retardancy of silicone rubber

The preparation of silicone rubber with excellent tracking resistance and flame retardancy is of great significance for application in high-voltage electrical insulation. Unfortunately, to date there lacks an effective strategy to simultaneously endow silicone rubber with satisfied tracking resistance and flame retardancy. In this work, aminopropyltriethoxysilane-modified MXene (APTES-MXene) was prepared by dehydrative condensation between the Si-OH in the hydrolyzed aminopropyltriethoxysilane (APTES) and the hydroxyl groups in MXene. The APTES-MXene was homogeneously dispersed in addition-cure liquid silicone rubber (ALSR). The effects of APTES-MXene on the tracking resistance and flame retardancy of ALSR were investigated. Incorporating 0.175 phr APTES-MXene and 15 ppm Pt catalyst enabled ALSR to pass 1A4.5 level, with a low erosion rate of only 0.29 %, indicating a significantly improved tracking resistance. Meanwhile, the 0.175 phr APTES-MXene also endowed ALSR a UL-94 V-0 rating and the limiting oxygen index (LOI) value reached 32.8 %. It was found that APTES-MXene and Pt catalyst synergistically promoted ALSR forming ceramic layer at elevated temperature. The mechanism for APTES-MXene improving the tracking resistance of ALSR was also proposed. This work provided new insights for high performance high-voltage insulation silicone rubber.