To improve the performance of rubber compounds using precipitated sili
ca as a reinforcing filler, the silica surface was directly modified b
y (1) adsorption of a surfactant, (2) adsolubilization of an organic m
onomer, (3) in situ polymerization of the monomer in the surfactant bi
layer, and (4) partial surfactant removal. Silica was thus surface mod
ified with polymerized styrene, isoprene, butadiene, and copolymers. S
tyrene-butadiene modification afforded the most promising candidate ba
sed on evaluation in a silica-filled model tire compound. Compound phy
sical testing showed that cure times were decreased, and break strengt
h, tear energy, elongation to break, and cut growth resistance were in
creased. Thus, surface modification of silica by the in situ polymeriz
ation of organic monomers affords unique materials useful in improving
rubber cure properties and cured compound physical properties. (C) 19
95 John Wiley and Sons, Inc.