Abstract: A polyurethane elastomer exhibiting a low glass transition temperature is provided, which comprises the reaction product of (a) a polyurethane prepolymer having terminally reactive isocyanate groups, prepared by reaction of a polymeric diol with a stoichiometric excess of 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate or a mixture of tolylene diisocyanates containing a major proportion of the 2,4-isomer, with (b) from 80 to 110% of the stoichiometrically required amount of 2,6-dichloro-p-phenylene diamine, and (c) from about 0.01 to 1 part per hundred of prepolymer of a conventional polyurethane catalyst.