Migration from food packaging containing a functional barrier: Mathematical and experimental evaluation

A model for predicting the functional barrier properties of layered films based on Fickian diffusion is presented along with experimental migration data from layered poly(ethylene terephthalate) films (PET) to test the model. Three-layered coextruded PET films were produced in which the center layer contained model solutes/contaminants and the outer layers were made with virgin material. The contaminants in the center layer were toluene and chlorobenzene. The PET films, which were 400 mu m thick, had barrier layers of 20, 30, 40, and 60 mu m of virgin coextruded PET. The center or core layer had thicknesses between 360 and 280 mu m. The amount of migration was measured into water, 3% acetic acid, and isooctane at temperatures up to 60 degrees C. The measured amount of migration through the different barrier thicknesses was predictable on the basis of the model presented. The effects of diffusion from the center layer to a virgin barrier layer during the coextrusion process must be considered if reliable predictions of migration are to be obtained.