Surface‐Modified Melamine Cyanurate/Silicone Rubber Composites With Improved Mechanical Properties, Aging Resistance and Flame Retardancy

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The deterioration of traditional flame‐retardant silicone rubber under accelerated thermal and radiation aging limits its use as an electrical material for safety equipment in nuclear power plants (NPPs). To address this issue, this study developed a silane coupling agent, a novel phosphorus‐containing polysilazane, and silicone resin, and prepared surface‐modified melamine cyanurate (MCAM‐x) to improve its compatibility with silicone rubber and the flame‐retardant effect. The introduction of MCAM‐x not only enhanced the mechanical properties of silicone rubber but also visibly improved its electrical insulating properties. Moreover, the MCA‐modified silicone rubber composites also exhibit excellent thermal stability, with low thermal decomposition rates and high residual carbon layers at elevated temperatures, helping to maintain the structural integrity of the material. In terms of flame retardancy, the modified silicone rubber shows excellent flame retardancy, with an increase in the limiting oxygen index (LOI) test and a V‐0 rating in the UL‐94 vertical flame test. After thermal aging and irradiation aging tests, the MCA‐modified silicone rubber shows excellent aging resistance, which ensures the stability of the material's physical and chemical properties during long‐term use, especially under extreme conditions. This provides a new solution for flame retardant modification of silicone rubber in high‐end application fields such as NPPs.