Patent ID: 8092905

Claim:
An uncured composition comprising: (i) a fluoroelastomer having at least one cure site; (ii) a multiolefinic crosslinker; (iii) a free radical polymerization initiator; and (iv) a nanosilica composite comprising: a plurality of nanosilica particles which have been reacted with a silicon compound having at least one vinyl group, said silicon compound selected from the group consisting of: disilazanes, a first silane having a hydrolysable functional group, and a hydrolysis product or a hydrolysis and condensation product of the first silane, said hydrolysis product or hydrolysis and condensation product formed by reacting the first silane with a nanosilicon oxide colloid containing greater than 0% water; and said nanosilica particles further having been reacted with a second silane having at least one acryloyloxy or methacryloyloxy functional group and a hydrolyzable functional group bonded to the silicon of the second silane, and at least one of a hydrolysis product or hydrolysis and condensation product of the second silane; wherein the hydrolysis product or hydrolysis and condensation product is formed by contacting the second silane, in the presence of a catalyst, with from about 1 to about 15 moles of water per mole of hydrolyzable functional group bonded to the silicon of the second silane.