The development of sago starch/kenaf fibre biocomposite films

Abstract

Interest in producing bio-based polymers is encouraging to support environmental rights. Fascinatingly, local natural resources such as sago starch can be converted into biopolymer and formed a thermoplastic starch. However, modification on the thermoplastic starch is required to overcome its poor mechanical and water absorption properties. In this present work, the thermoplastic sago starch (TPSS) was reinforced with Kenaf bast fibre and fabricated by film casting technique. TPSS formulation was initially determined by statistical experimental model Central Composite Design (CCD). CCD optimized the TPSS formulation of having 8.14 g of sago starch, 3.79 g of glycerol and 86.71 g of distilled water, to attain a minimum water absorption and maximum tensile strength predicted at 75.53% and 1.97 MPa, respectively. The effect of Kenaf fibre content (1, 2, 3, 4 and 5 (%wt.)) on the optimized TPSS was further investigated through mechanical (tensile test), physical (water absorption test), failure modes and morphological (Scanning Electron Microscope (SEM)), biodegradable (soil burial test) and thermal (TGA) properties. Tensile properties showed an improvement with the addition of Kenaf fibre and the optimum tensile strength of 9.63 MPa was achieved at 4 (%wt.) of Kenaf fibre content. Water absorption, however, increased with increasing of fibre content. Biodegradable test showed that TPSS attained 90.7% of weight loss after 60 days of burial, higher than the reinforced biocomposite films. Consequently, the effect of citric acid content (1, 5, 10, 15 and 20 (%wt.)) on the sago starch/Kenaf fibre biocomposite films was also investigated. Both tensile strength and water resistance of the biocomposite films were improved with the addition of 5 wt.% of citric acid content. The optimum tensile strength and water absorption were attained at 10.57 MPa and 42.45%, respectively. Conversely, biodegradation rate of the cross linked films reduced with higher citric acid concentration. Thermal property was enhanced with the addition of higher Kenaf fibre and citric acid content.