Food sandwich packaging with a recycled polymer between two functional barriers of different thicknesses

The process of pollutant transfer is studied through a sandwich packaging made of recycled polymer located between two functional barriers. These three layers are made of the same polymer but they have different thicknesses. The initial concentration of the pollutant in the recycled polymer is uniform and the diffusivity is the same in the three layers. There is no pollutant transfer through the external surfaces, so the study simulates the process of pollutant transfer through the sandwich before its use as food packaging. The results are expressed in terms of dimensionless numbers in order to provide general results of use in any particular case: the profiles of concentration of pollutant developed through the thickness of the sandwich, the kinetics of pollutant transferred and the pollutant concentration-time histories on each external surface.