Preparation of rubber compositions containing syndiotactic polybutadiene filament and rubber composition and tire

A rubber composition is disclosed comprising a blend of, based on parts by weight per 100 parts by weight rubber (phr), where the term rubber excludes syndiotactic polybutadiene polymer: (A) a polymer alloy comprising 2 to 50 parts by weight of a dispersion of micro sized syndiotactic polybutadiene domains comprising filaments thereof, preferably primarily of filaments thereof, in 98 to 50 parts by weight cis 1,4-polyisoprene rubber; and (B) 100 phr of sulfur curable diene-based elastomers comprising cis 1,4-polyisoprene rubber, preferably the cis 1,4-polyisoprene rubber, and at least one additional diene-based elastomer; wherein the rubber composition comprises the alloy in a sufficient quantity to provide from 2 to 50 phr of the filamentary syndiotactic polybutadiene, and (C) 0 to 150 phr of a reinforcing filler comprising: (1) carbon black, or (2) a combination of silica or precipitated silica and carbon black. [0002] The rubber composition may be used in a tire. Also, a process of manufacturing such a rubber composition is disclosed.