This invention is based upon the discovery that elongated silica has
superior characteristics for reinforcing rubbery elastomers as compared
to conventional silica. More specifically, elongated silica provides a
higher level of reinforcement for elastomers at the same level of
loading. Accordingly, elongated silica can be employed to attain an
equivalent level of reinforcement at a lower level of loading. This
results in lower weight compositions and potential cost savings. Rubber
compounds that are reinforced with elongated silica offer significant
advantages in tires including reduced rolling resistance, increased tread
life, and, of course, reduced weight. The subject invention more
specifically relates to a silica reinforced rubber composition which is
comprised of (1) a rubbery polymer and (2) an elongated silica, wherein
the elongated silica has a width that is within the range of about 5 nm
to about 40 nm and wherein the elongated silica has a length of about 40
nm to about 300 nm. The present invention also discloses a process for
preparing a silica reinforced rubber composition which comprises (1)
adding an elongated silica to a latex of a rubbery polymer, and (2)
recovering the silica reinforced rubber composition from the latex.