Abstract: A free-flowing silicone polymer powder, having an average particle size of 1 to 1000 microns and prepared by mixing a polydiorganosiloxane with a silica filler, is uniformly dispersed in an organic resin using conventional equipment, such as a single screw or, preferably, a twin screw extruder. When employed at a concentration of about 0.5 to 25 parts by weight of powder per 100 parts by weight of resin, a significant improvement in the burn character of the modified resin is obtained such that the rate of heat release, generation of smoke and evolution of toxic carbon monoxide gas is significantly reduced relative to the unmodified resin.

Abstract: A free-flowing silicone polymer powder, having an average particle size of 1 to 1000 microns and prepared by mixing a polydiorganosiloxane with a silica filler, is uniformly dispersed in an organic resin using conventional equipment, such as a single screw or, preferably, a twin screw extruder. When employed at a concentration of about 0.5 to 25 parts by weight of powder per 100 parts by weight of resin, a significant improvement in the burn character of the modified resin is obtained such that the rate of heat release, generation of smoke and evolution of toxic carbon monoxide gas is significantly reduced relative to the unmodified resin.