Utilization of sago starch, waste palm cooking oil (WPO), and densified CO2 in the synthesis of starch-based bioplastics

Abstract

The incentive to produce thermoplastic material from renewable and biodegradable resources including the utilization of waste cooking oil and the application of “green’ solvent in plastics synthesis has arisen in the last decade. This due to the urgency to solve several problems existed in the conventional plastics production and their consumption, i.e : the depletion of fossil fuel as the major resources for many polymer precursors, the enormous amount of plastics waste produced annually and the application of various organic solvents which give a high environmental impact. In this work, two different starch-based bioplastics which are thermoplastics starch (TPS) and fatty acid starch ester (FASE) were produced via extrusion of sago starch with glycerol, palm cooking oil (PO) and WPO and transesterification of sago starch with WPO in densified CO2, respectively. Fatty acid starch ester (FASE) with a broad range of ester content (EC of 21.2 – 701.3 meq/kg) were obtained within the experimental window. The presence of fatty acid in the starch backbone is confirmed with FT-IR (carbonyl (C=O) absorption peak at 1720 – 1740 cm-1) and 1H-NMR analyses (proton of fatty acid group at δ of 0.8 – 2.2 ppm). FASE products show significant changes in the morphology and thermal properties compared with the ones of the native sago starch suggesting the potential used of WPO as fatty acid resources and densified CO2 as solvent in FASE synthesis. Furthermore, an improve in the mechanical properties of native sago starch after extrusion processes was achieved where a maximum tensile strength of 5.2 MPa, modulus of 481.93 MPa and elongation at break of 34.45 % of TPS products are accessible. The finding in this work gives a new insight on the potential application of sago starch and WPO as the raw material and densified CO2 as solvent for starch-based bioplastics synthesis.