Significant improvement of urethane-containing silane on the tracking and erosion resistance of silicone rubber/silica nanocomposite by enhancing the interfacial effect

Rapid crosslinking of silicone chains on the nanosilica surface during arc discharge is proposed as an efficient strategy to improve the tracking and erosion resistance of silicone rubber. Urethane-containing silane (URS) was synthesized by using (3-isocyanatopropyl) triethoxysilane, isopropyl alcohol and allyl alcohol via nucleophilic addition and trans-etherification. The suppression effect and mechanism of URS on the tracking and erosion of addition-cure liquid silicone rubber/silica (ALSR/SiO2) nanocomposite were investigated. It was found that URS could significantly enhance the tracking and erosion resistance of ALSR/SiO2. When only 2.5 phr URS was added, all the ALSR/SiO2/URS specimens passed the inclined plane test at 4.5 kV and the erosion rate decreased from 3.44% to 0.25%. This might be because URS tightly constrained silicone chains on the SiO2 surface by strong hydrogen-bonding interactions. During arc discharge, URS at the interphase enhanced the catalytic activity of platinum compound to promote the radical crosslinking of silicone chains absorbed on the SiO2 surface. Hence, a compact and intact ceramic layer was quickly formed on the ALSR surface and protected the underlying materials from further arc ablation. Our finding provides a new method and theoretical basis for the design, preparation and application of the novel high-performance polymer insulating material.