Novel ethylene/norbornene copolymers as nonreleasing antioxidants for food-contact polyolefinic materials

An efficient procedure for the copolymerization of ethylene (E) with a novel norbornenic comonomer (NArOH) bearing a stabilizing moiety analogous to commercial antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT) is successfully developed. This study is aimed at: i) tuning the concentration of the stabilizing function along the polymer chain, and ii) preparing "nonreleasing" polymeric additives specifically destined to protect commercial low-density polyethylene (LDPE). Films obtained from blends of the novel E/NArOH copolymers with an antioxidant-free LDPE matrix are characterized by superior thermal, thermo-oxidative, and photostability when compared not only with neat LDPE films but also with films stabilized by the commercial BHT additive. Specific migration tests conducted in order to investigate the nonreleasing character of the novel macromolecular additives confirm the reduced risk of migration, from the films into food simulants, of unreacted comonomer or degradation products bearing the antioxidant moiety.