the present invention relates to an antidegradant system comprised of an antidegradant selected from the group consisting of phenolic antidegradants , amine antidegradants and mixtures thereof ; and a unique polymerizable synergist . in addition , there is disclosed a stabilized polymer comprising a polymer selected from the group consisting of homopolymers and copolymers of monoolefins ; natural rubber ; and synthetic rubber derived from a diene monomer ; from about 0 . 05 to about 10 parts by weight based upon 100 parts of polymer of an antidegradant selected from the group consisting of phenolic antidegradants , amine antidegradants and mixtures thereof ; and from about 0 . 05 to about 20 parts by weight based upon 100 parts of polymer of a unique polymerizable aromatic sulfide synergist .