Abstract: At least partially vulcanized elastomers are described, these elastomers obtained by at least partially crosslinking (1) an elastomeric polymer containing reactive substituents with (2) a crosslinking agent (a) containing two or more reactive substituents differing from those contained in the elastomeric polymer, and (b) having a number average molecular weight less than about 2000, each of the reactive substituents selected (i) such that those of the elastomer will react with those of the crosslinking agent to at least partially crosslink the elastomer, and (ii) from the group consisting of carboxylic acid, carboxylic anhydride, carboxylic acid salt, carbonyl halide, hydroxy, epoxy, and isocyanate.