This invention relates to blends of a specific type of cis-l,4-
polybutadiene rubber with other rubbery polymers, such as
natural rubber, synthetic polyisoprene rubber,
styrene-butadiene rubber,
isoprene-butadiene rubber and / or
styrene-
isoprene- butadiene rubber. The cis-1,4-
polybutadiene rubber utilized in the blends of this invention is synthesized by polymerizing 1,3-butadiene in the presence of (a) an organonickel compound, (b) an organoaluminum compound, (c) a
fluorine containing compound and (d) para-styrenated
diphenylamine; wherein the organoaluminum compound and the
fluorine containing compound are brought together in the presence of the para-styrenated
diphenylamine. The cis-1,4-
polybutadiene rubber blends of this invention offer improved processability and enhanced physical properties. For instance, improved mixing which results in better incorporation of pigments and fillers, such as
carbon black and silica, at lower levels of
power consumption is realized. Additionally, improvements in
extrusion characteristics and in
tear resistance with little sacrifice in hysteretic properties, abrasion resistance and modulus are also attained with the rubber blends of this invention. The rubber blends of this invention can be used in manufacturing a wide variety of rubber products, such as tires, hoses, belts, golf balls, tennis balls, racquet balls,
golf club grips, stoppers, plungers, tubing, straps, diaphragms, motor mounts, bushings, weather stripping,
windshield wiper blades, shoe soles, other molded rubber products and adhesives.