Improving physical and mechanical properties of sodium alginate films with clay nanoparticles

Due to problems caused by petroleum-based packaging materials, biopolymers and their biodegradable films have received great attention all over the world in the last two decades. But the use of biopolymers films in food packaging due to their inherent water sensitivity and poor mechanical properties has been limited. A novel practical way for improving the properties of natural biopolymer films is the formation of nanocomposites. Thus, the main objectives of this study were to prepare alginate/clay nanocomposite films and to investigate the effect of montmorillonite concentrations on the properties of the prepared alginate-based nanocomposite films. A bio-based nanocomposite was developed by incorporation of clay nanoparticles (MMT) into alginate biopolymer using the solution casting method. The effect of MMT loading content (1, 3 and 5 wt%) on mechanical properties, color , water solubility, water vapor permeability, XRD and SEM of the nanocomposites were evaluated. Results showed that increasing the MMT content to 3% have improved the tensile strength and water vapor permeability of the nanocomposites up to 14% and 21%, respectively. The water solubility value of the nanocomposite films decreased about 30% compared to pure alginate films. Results of X-ray diffraction (XRD) revealed well developed exfoliated nanocomposite films especially at low level of nanoclay addition.
Properties of alginate films are greatly influenced by the content of the clay nanoparticles and the films containing 3% clay nanoparticles showed the best physical and mechanical properties.