Biodegradable Corn Starch/Silica Nanocomposite Sheets for Food Packaging Applications

The use of nanomaterials for food packaging has been steadily increasing globally and is already a billion dollar industry. There is also growing interests in developing safe and environment-friendly packaging materials. This study developed a corn starch-based nanocomposite sheet using nanosilica from recycled biodegradable rice hull ash using sol-gel method. The nanosilica extraction yield was 80.41% with purity of about 99%. The sizes of extracted silica particles and agglomerated nanosilica are 6.33 ± 1.62 nm (using atomic force microscopy) and 41.67 to 72.92 nm (using scanning electron microscope), respectively. The specific surface area of the nanosilica was 108.54 m2/g with pore radius of 9.07 nm. Nanocomposite sheets from mixture of nanosilica and corn starch matrix, were produced using three different extrusion temperature profiles and three different nanosilica concentration of 1%, 2% and 3%. Addition of nanosilica improved the mechanical properties of the nanocomposite sheets. Tensile strength increased, while elongation at break decreased. Nanocomposite sheets with nanosilica displayed improved water resistance while those without nanosilica disintegrated within two hours of immersion in distilled water at 25 °C.