Construction of Micro‐Crosslinked Carrier Barrier Network: Enhancing Dielectric and Mechanical Properties of Silicone Rubber

High‐temperature vulcanized silicone rubber (SiR) is widely utilized as additional insulation in high‐voltage direct current (DC) cable accessories due to its excellent insulation and mechanical properties. However, under prolonged electro‐thermal‐mechanical coupling conditions, the tensile and torsional forces exerted on the cable accessories can disrupt the intermolecular forces of the SiR, leading to a decrease in insulation resistance. As a result, the initial breakdown voltage at the heterogeneous interface between the SiR and cross‐linked polyethylene significantly decreases, making it highly susceptible to interfacial discharge faults. To address this critical insulation weakness, cinnamonitrile small molecules, known for their high insulating properties, are introduced as cross‐linking agents into the SiR, thereby enhancing its mechanical performance. These cinnamonitrile molecules also exhibit strong electron‐repelling characteristics, which can effectively scatter electrons within the rubber matrix, improving the DC breakdown strength and breakdown voltage at the heterogeneous interface. This study is based on fully organic modification, and the experimental scheme is conducive to engineering applications. It holds significant importance for enhancing the reliability of high‐voltage DC power transmission and promoting the development of higher voltage levels.