Macromolecular non-releasing additives for safer foodpackaging: application to ethylene/a-olefns and propylenebased polymers

Some innovative solutions are proposed to the problem of the unavoidable physical migration of antioxidants from plastic flms for packaging, in order to minimize the consequent undesirable effect of food contamination.In previous exploratory tests, phenolic antioxidant co-units were achieved and incorporated into polyethylenechain and now the work is extended to create new families of polymeric additives properly designed for specifcmaterials. An effective route was designed to synthesize the functionalized comonomer, analogues of commercial2,6-t-butyl-4-methoxy-phenol (BHA), containing eight methylene units as spacer between the aromatic ring and thepolymerizable olefnic double bond (C8). Ethylene/1-hexene/C8 terpolymers, with 1-hexene concentration in thetypical range found in commercial polyethylene grades, and propylene/C8 copolymers with microstructure similarto those of commercial packaging polypropylenes were produced. A careful 13C NMR study was conducted for theprecise determination of the functionalized comonomer content on all terpolymer and copolymer samples. Thesamples melt blended with additive-free commercial LDPE and PP matrices, individually, were analyzed in termsof thermal and thermo-oxidative stability and compared with LDPE and PP flms containing the traditional BHAadditive analogue. The results demonstrate that, in either way, the polymeric additives exert a very positive effecton the degradation temperature of the polymeric matrices, retarding the thermo-oxidative sequence of reaction.Polyolefns J (2014) 1:1-15

Keywords:

macromolecular antioxidants , blends , polyolefns , 13C NMR , thermogravimetric analysis (TGA)