title: Typical diffusion behaviour in packaging polymers - application to functional barriers.
abstract: When plastics are collected for recycling, possibly contaminated articles might be recycled into food packaging, and thus the contaminants might subsequently migrate into the food. Multilayer functional barriers may be used to delay and to reduce such migration. The contribution of the work reported here is to establish reference values (at 40 degrees C) of diffusion coefficients and of activation energies to predict the functional barrier efficiency of a broad range of polymers (polyolefins, polystyrene, polyamide, PVC, PET, PVDC, [ethylene vinyl alcohol copolymer], polyacrylonitrile and [ethylene vinyl acetate copolymer]). Diffusion coefficients (D) and activation energies (Ea) were measured and were compiled together with literature data. This allowed identification of new trends for the log D=f(molecular weight) relationships. The slopes were a function of the barrier efficiency of the polymer and temperature. The apparent activation energy of diffusion displayed two domains of variation with molecular weight (M). For low M (gases), there was little variation of Ea. Focusing on larger molecules, high barrier polymers displayed a larger dependence of Ea with M. The apparent activation energy decreased with T. These results suggest a discontinuity between rubbery and glassy polymers.
authors.affiliation: INRA SquAlE, Reims, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: Dole
authors.forename: Alexandre E
authors.initials: AE
authors.lastname: Feigenbaum
authors.forename: Carlos
authors.initials: C
authors.lastname: De La Cruz
authors.forename: Sara
authors.initials: S
authors.lastname: Pastorelli
authors.forename: Perfecto
authors.initials: P
authors.lastname: Paseiro
authors.forename: Thomas
authors.initials: T
authors.lastname: Hankemeier
authors.forename: Yiannis
authors.initials: Y
authors.lastname: Voulzatis
authors.forename: Susana
authors.initials: S
authors.lastname: Aucejo
authors.forename: Philippe
authors.initials: P
authors.lastname: Saillard
authors.forename: Costas
authors.initials: C
authors.lastname: Papaspyrides
mesh_terms: D000180:Acrylic Resins; D003247:Conservation of Natural Resources; D005506:Food Contamination; D018857:Food Packaging / Q000379:methods*; D008970:Molecular Weight; D009757:Nylons; D010969:Plastics; D011090:Polyenes; D011093:Polyethylene Terephthalates; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes; D011143:Polyvinyl Chloride; D011145:Polyvinyls; D012016:Reference Values
chemical_list: D000180:Acrylic Resins; D009757:Nylons; D010969:Plastics; D011090:Polyenes; D011093:Polyethylene Terephthalates; D011108:Polymers; D011137:Polystyrenes; D011145:Polyvinyls; C016438:ethylenevinylacetate copolymer; C010504:polyacrylonitrile; C020320:ethylene-vinyl alcohol copolymer; C035051:PL 732; D011143:Polyvinyl Chloride