Extrudable curable organosiloxane compositions exhibiting reduced compression set

摘要

Cured organosiloxane elastomers exhibiting compression set values of 25% or less with no adverse affect on other physical properties are prepared from organosiloxane compositions curable by a platinum-catalyzed hydrosilation reaction and containing a reinforcing silica filler that has been treated with at least one organosilicon compound that is a hexaorganodisilazane wherein two of the silicon-bonded hydrocarbon radicals are alkenyl. The hexaorganodisilazane constitutes from 1 to 4.6 weight percent of the organosilicon compounds used to treat the silica filler and the molar ratio of silicon-bonded hydrogen atoms to alkenyl radicals in the curable composition is from 0.8 to 2.0, preferably from 1 to 1.5.