Construction and Properties of Radiation-Crosslinked Halogen-Free Flame-Retardant Ceramizable-Silicone-Rubber Composites

As a novel type of refractory material, ceramizable-silicon-rubber composite has broad application potential in the wire and cable industry. To improve the mechanical strength and flame retardancy of materials, three halogen-free flame-retardant ceramizable-silicone-rubber insulation materials with different compositions suitable for radiation-crosslinking process were constructed by using methyl vinyl silicone rubber (MVSR) as the matrix. It was found that the mechanical strength and moduli of ceramicable-silicone-rubber composites could be greatly improved after ⁶⁰Co (γ-ray) radiation crosslinking. Among them, Composite-3 with allyl-functionalized cyclotriphosphazene (CP-Allyl) and Mg(OH)₂ as synergistic flame retardant exhibited the better radiation crosslinking effect and flame retardancy. The tensile strength of Composite-3 treated by a dose of 80 kGy could reach 4.65 MPa, and its limiting oxygen index was 34.4%. In addition, these composites could form dense and hard ceramic layers after high-temperature ablation at 700-1 000 ℃. As a result, the radiation-crosslinked silicone-rubber composites with a good performance and a high-temperature ceramic forming ability are expected to be applied in the field of insulation materials for wires and cables.