| abstract |
This invention discloses an emulsion styrene-butadienenrubber (SBR) that can be employed innmanufacturing tire tread formulations that havenrolling resistance and treadwear characteristics thatnare similar to those made with solution SBR but withnimproved traction characteristics. Thus, the emulsionnSBR of this invention is superior in many respects fornuse in tire tread compounds to conventional solutionnSBR and conventional emulsion SBR. This inventionnmore specifically discloses a styrene-butadiene rubberncomposition which is comprised of repeat units whichnare derived from styrene and 1,3-butadiene, whereinnthe styrene-butadiene rubber composition has a numbernaverage molecular weight as determined by thermalnfield flow fractionation which is within the range ofnabout 50,000 to 150,000, and wherein the styrene-butadienenrubber has a light scattering to refractivenindex ratio which is within the range of 1.8 to 3.9.nThe subject invention further reveals a styrene-butadienenrubber composition which is comprised ofnrepeat units which are derived from styrene and 1,3-butadiene,nwherein a plot of log frequency versusnstorage modulus of the styrene-butadiene rubberncomposition crosses over a plot of log frequencynversus loss modulus of the styrene-butadiene rubberncomposition at a log frequency within the range ofn0.001 radians per second to 100 radians per secondnwhen conducted at 120°C using parallel plate geometrynin the dynamic oscillation frequency sweep of thenstyrene-butadiene rubber. |