Studies on the properties and biodegradability of PVA/Trapa natans starch (N-st) composite films and PVA/N-st-g-poly (EMA) composite films.

The morphological modification of Trapa natans starch was done by grafting the methylmethacrylate (EMA) using ferrous ammonium sulphate‑potassium persulphate as a redox initiator. Different reaction parameters such as reaction temperature, time, monomer concentration, pH and solvent were optimized to get maximum graft yield (56%). The graft copolymers thus formed were characterized by Fourier transform infrared, scanning electron microscopy, X-ray diffraction and TGA/DTA/DTG techniques. PVA/starch (N-st) composite films and PVA/N-Starch-grafted-poly (EMA) composite films were prepared separately by using glycerol as a plasticizer. The effect and content of grafted starch on the mechanical properties, water uptake (%), and biodegradability of the composite films were observed. Elongation at break % of PVA/starch-grafted-poly (EMA) (1:1) increased up to 38.9% of pure PVA/N-starch composites (1:1). With further increase in the ratio of grafted starch from (50% to 70%) Elongation at break, % increased to a great extent. There was 223.14% increased in PVA/starch-grafted-poly (EMA) (3:7) as compared to pure PVA/N-starch (3:7) composite films. The Max stress increased up to 100% in PVA/N-starch-grafted-poly (EMA) (3:7) composite film of pure PVA/N-starch composite films (3:7). There were 41.63% decreases in water uptake in PVA/N-starch-grafted-poly (EMA) (3:7) composite films as compared to PVA/N-starch composite films.