Experimental and Mathematical Assessment of Migration from Multilayer Food Packaging Containing a Novel Clay/Polymer Nanocomposite

A novel clay/polymer composite film was prepared by applying a modified clay polymer suspension containing montmorillonite nanoparticles onto bi-axially oriented polypropylene films to form three-layer barrier film via lamination. The suitability of the film to be used as a food contact material was assessed with a focus on two-side migration into specified food simulants (water, 3 % acetic acid, 15 % ethanol, olive oil, grapeseed oil and coconut oil) under three different temperatures. It was found that migration levels increased with increasing contact time and temperature. Among the aqueous food simulants tested, the 3 % acetic acid solution demonstrated the highest migration levels, while the water was the least efficient migrating medium. Migration into fatty simulants was observed to be greater than those into aqueous solutions, but independent of their fatty acid composition. The results provided adequate guarantees for the developed film to be applied for food packaging materials. A numerical model based on Fick's diffusion theory was developed to predict the extent of migration from the multilayer film at any time of exposure in aqueous simulants. Measurements of migration were combined with computer simulations to yield reliable estimates of the diffusion and partition coefficients in the system, which showed an Arrhenius behaviour. The model was solved using a finite element method, and the predicted results and experimental data agreed very well, indicating the rate-controlling steps of diffusion within the polymer in the migration process.