Biodegradable Barrier Membranes Based on Nanoclays and Carrageenan/Pectin Blends

The aim of this work is the study of the barrier properties of biodegradable membranes based on commercial pectin and kappa-carrageenan and organically modified nanoclays. Membranes (67% k-carrageenan, 33% pectin) with different amounts of nanoclays (1, 5 and 10%) were prepared by the solution intercalation method and casting. The films exhibited enhanced gas and water vapour barrier properties when compared to the ones without nanoclay particles. A water vapour permeability reduction of 35% for a nanoclay loading of 10 % was observed. The positive impact on the films' barrier properties of the organic nanoclay particles inclusion, results from a combined effect of increased tortuosity and reduction of water sorption due to the hydrophobic nature of the clay. The permeability to carbon dioxide has been significantly reduced (50% reduction for 1% nanoclay content). Scanning electron microscopy coupled with energy dispersive X-ray spectroscopy analysis indicated the presence of under exfoliated nanoclay aggregates at 10%. The membranes have also shown a decrease of their stiffness and an increase of the elongation at break with the inclusion of nanoclay particles. An attenuation of the membranes transparency was observed, however, the colour measured after the application of test membranes on coloured paper sheets, did not change significantly with the inclusion of nanoclay particles.