LDPE-based blends and films stabilized with nonreleasing polymeric antioxidants for safer food packaging

Several novel random copolymers of ethylene and 1-olefin counits bearing a highly efficient phenolic antioxidant moiety placed at different distances from the polymerizable double bond were prepared in the presence of a metallocene catalyst. These copolymers were melt-blended with an antioxidant-free LDPE in an internal batch mixer to obtain innovative materials containing nonreleasing polymeric antioxidants suitable for safer food packaging applications. Blends and films, obtained by compression molding, were tested for their thermal and thermo-oxidative stability by thermogravimetric analysis both in dynamic and isothermal conditions. Films containing the macromolecular antioxidants showed a longer induction time before O2 uptake starts and, consequently, a higher degradation temperature than neat LDPE or LDPE containing a low molecular weight commercial additive. Aging tests demonstrated that the new polymeric antioxidants also exert a valid protection against photo-oxidation. Eventually, migration tests demonstrated the absence of any trace of products containing the antioxidant moiety when the films were kept in contact with a food simulant.