Disproportionated rosin (DPR) is compound of dehydroabie acid and dihydroabtice acid, the DPR is processed through catalytic reaction of gum rosin on proper temperature. In the synthetic rubber industry, DPR is used as emulsifier in the producing of various products including styrene-butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber and acrylonitrile-butadiene-styrene rubber. Using DPR as an emulsifier, rubber product will improve in cohesion, and the endurance to heat will increase for 25%. The endurance to both abrasion and laceration of this rubber is better than ordinary styrene-butadiene rubber. The cohesion will be greatly enhanced if blended with natural rubber.