| 摘要 |
A modified organopolysiloxane composition is provided herein. Such organopolysiloxane composition is obtained from the polymerization of (1) a monomer having ethylenic unsaturation in the presence of (2) an organohydrogenpolysiloxane fluid having a viscosity of from 10 to 1,000,000 centipoise at 25.degree.C., in which the organohydrogenpolysiloxane fluid is present in an amount of from 20 to 95 percent by weight based on the weight of monomer (1) and organohydrogenpolysiloxane (2) and (3) a free radical initiator to form a composition having in-situ generated particulate matter dispersed therein and having a polymeric organic group which is constituted of recurring units derived from monomer (1) grafted to the organohydrogenpolysiloxane(2). The composition contains in-situ generated particulate matter. The particulate matter results from the polymerization of monomer (1) in the presence of organohydrogenpolysiloxane (2) and free radical initiator (3),(b) a vinyl containing compound having at least two vinyl groups per molecule which is capable of crosslinking with (A) and (C) a catalyst capable of promoting the addition of silicon-bonded hydrogen groups to silicon-bonded vinyl groups. A process is also provided for preparing such composition, the process comprising reacting an organohydrogenpolysiloxane with an organic monomer in the presence of a free radical initiator at an elevated tempersture. The resultant composition may be combined with vinyl containing compounds having at least two vinyl groups per molecule and a catalyst which promotes addition of SiH groups to vinyl groups to form elastomers. These organopolysiloxane compositions have improved physical properties, e.g. the mixture is homogeneous, and the composition does not shrink on curing, thus making it essentially suitable for use as molding or potting compositions. |
