Abstract: Silicone rubber is an organic-inorganic material, and is an excellent flame retardant material, which has been applied in many fields. After expansion, silicone rubber can expand its application in high- end manufacturing and power cable protection.The intumescent flame retardancy of silicone rubber was studied by using expandable graphite as intumescent flame retardant and adding different content of aluminum hypophosphite.The characteristics were investigated by oxygen index, vertical combustion UL-94, thermal analysis, tensile and volume change tests. The results show that the silicone rubber is the UL-94 V-0 grade while the additive content is 1:1, and the oxygen index can be up to 40.8%, what's more, mechanical properties have reached the best. From the cone measurement results, when the two were mixed, the PHRR decreased from 455 kW/m2 to 250 kW/m2 ,with good expansion effect and the carbon layer strong strength.

Key words: composite; high temperature vulcanized siliconerubber, intumescent flame retardant；expandable graphite；aluminumhypophosphite