N-Vinylcarbazole Group Grafted Modified Silicone Rubber for Dielectric Performance Improvement of High-Voltage Insulation

Silicone rubber serves as a critical insulating material in electrical engineering due to its outstanding antifouling characteristics, mechanical robustness, and electrical performance. Nevertheless, its insulating properties require further enhancement to meet the demanding requirements of ultra-high voltage (UHV) applications, particularly for long-distance, high-capacity power transmission. In this work, we developed an improved insulating silicone rubber by grafting p–p conjugated N -vinyl carbazole (VK) groups—known for their space charge trapping capability—onto thiol-silicone oil, followed by cross-linking with end-methyl branched vinyl silicone oil. The modified material demonstrated optimal insulating performance at a VK group concentration of 0.5 wt%, achieving a 23.19% increase in breakdown field strength compared to unmodified silicone rubber films. This study provides a viable approach for enhancing the dielectric strength of polymer-based silicone rubber materials.