Effect of Nanoclay and Cross-Linking Degree on the Properties of Alginate-Based Nanocomposite Film

Montmorillonite nanoclay (MMT) and CaCl2-reinforced alginate-based nanocomposite film was prepared by solvent casting method. The combined effect of nanoclay addition and internal cross-linking degree on the mechanical and physical properties of the obtained nanocomposites was evaluated. The MMT concentration was 3% and CaCl2 content in the matrix was varied from 0.01 to 0.03 ([w/w] % dry matrix). Results showed that the water vapor permeability and water solubility of the nanocomposite films significantly (P < 0.05) decreased about 30% and 39%, respectively, with the addition of MMT and CaCl2. Incorporation of both nanofiller and cross-linking agent also improved the mechanical performance of the nanocomposites (increase in tensile strength up to 36%) compared to the neat alginate film. Nevertheless, hydrophilicity of the nanocomposite films increased with incorporating both nanoclay and CaCl2, resulted in decreased contact angle. Results on X-ray diffraction revealed well-developed exfoliated nanocomposite films at 3 wt % of nanoclay addition. Practical Applications The importance of packaging in the food supply chain is fully recognized. In the last two decades, due to increasing environmental concerns, great efforts have been expended to extend food shelf life and quality while reducing post-consumption disposal waste of packaging materials. These endeavors have led to the development of new bio-packaging materials called biodegradable films, produced using biopolymers. These polymers are considered environmentally friendly and attractive materials with interesting properties and functionalities that can improve food preservation in the film form.