Effect of LAPONITE® addition on the mechanical, barrier and surface properties of novel biodegradable kafirin nanocomposite films

The objective of this research was to evaluate the effect of LAPONITE (R) addition on mechanical, surface and barrier properties of kafirin films. Kafirin was extracted using 70% ethanol, sodium metabisulphite and glacial acetic acid at 70 degrees C, which gave it a less hydrophobic character compared to earlier studies as determined using water contact angle (WCA) and secondary structure analysis through FTIR. Kafirin was then plasticized with equal concentration of lactic acid, glycerol and poly ethylene glycol and then loaded with different concentrations of LAPONITE (R) (1, 3, 5 and 10% by weight). Kafirin nanocomposite films were characterized using FTIR, water vapor permeability (WVP), water contact angle (WCA), mechanical properties, optical microscopy and transmission electron microscopy (TEM). Collectively these measurements helped understand the interaction of LAPONITE (R) with kafirin in the film matrix. The a alpha-helix and 13 beta-sheet content correlated with the relative hydrophilicity. Addition of LAPONITE (R) into kafirin films made the films stronger and less ductile while the WVP did not show any significant change. The new information obtained from this study can help in fabricating improved biodegradable films that can be used in various packaging, coating, biomedical and other functional film applications.