A dynamically vulcanized alloy contains at least one isobutylene-containing elastomer, at least one thermoplastic resin, and an anhydride functionalized oligomer grafted to the thermoplastic resin. In the alloy, the elastomer is present as a dispersed phase of small vulcanized or partially vulcanized particles in a continuous phase of the thermoplastic resin and the alloy is substantially absent of any sulfonamides.