Preliminary evaluation of the properties and biodegradability of glycerol- and sorbitol-plasticized potato-based bioplastics

A huge amount of plastic wastes caused disastrous effects to the environment. Pertaining to the adverse effects imposed by these wastes, a significant progress is observed in the development of biodegradable plastics using natural raw materials such as starch from potato or corn to produce biodegradable plastic materials with similar functionalities to that of petroleum-based polymers. The present study aimed to investigate the effects of glycerol and sorbitol as plasticizing agents on the properties and biodegradability of potato-based bioplastic. Bioplastic films were produced by varying the type and concentration of plasticizers at the ratio of 15, 30 and 45 (wt%) using solution casting technique. The characterization results revealed that plasticized films were less fragile and more flexible compared to those of 0% plasticizer. Plasticized film with higher concentration of plasticizers demonstrated lower tensile strength with increased elongation at break value. Higher water vapour transmission was also observed for plasticized films as the concentration of plasticizers was increased, indicated higher water permeability but lower water absorption ability of the films. The addition of plasticizers effectively reduced the swelling and water retaining capacity of potato-based biodegradable plastic films. From the Fourier Transform Infrared spectra, similar absorption bands were obtained for both the pure potato starch powder and plasticized films, indicating no significant chemical interaction between the starch and plasticizers which could alter their respective functional groups. Insignificant biodegradation was observed using soil burial test for one week, but slight mass reduction and plastic swelling were observed at low plasticizer concentrations.