Determination of gas diffusion and permeability of polymeric food packaging materials with moment technique

Food packaging materials, which are in membrane nature, produced from polymers such as polyvinylchloride (PVC), polyethylene (PE), polypropylene (PP), polystyrene (PS) and polyamide (PA) are frequently used to protect foods from bad odors, gas, light and moisture. Therefore, knowing the transport properties of gases and vapors through polymeric packaging materials plays an important role in the choice of polymeric packaging materials. In this study, the transport of gases such as He, N2 and CO2, and H2O vapor through polymeric food packaging materials, such as PVC stretch film and LDPE refrigerator bags using different temperatures (30, 40 and 50 °C) at isobaric and non-isobaric conditions (2 -20 kPa pressure difference) was studied. The coefficients of diffusion (De), solubility (S) and permeability (Pe) of gas tracers and water vapor through the packaging materials were determined by analysis of zero and first absolute moment data obtained experimentally. At isobaric conditions and for all temperatures studied, De values of gases and water vapor in PVC decreased in the order of He> CO2> N2> H2O and S values followed the order of H2O> CO2> N2> He while Pe values decreased in the following order: CO2> He> N2> H2O. For LDPE, De values of gases decreased in the order of He> CO2> N2, S values followed the order of CO2> N2> He and Pe values decreased by following the order of CO2> He> N2. LDPE was found to be more permeable than PVC against gas and water vapor. At isobaric conditions, the values of De and Pe of gases and water vapor in PVC and LDPE packaging materials increased with temperature while S values decreased with the incresing temperature. There was no significant change in the values of De, S and Pe with increasing pressure difference.