Preparation and characterization of starch-based bioplastic composites with treated oil palm empty fruit bunch fibers and citric acid

The present paper described the preparation and characterization of starch-based bioplastic composites reinforced by treated oil palm empty fruit bunch fibers and citric acid (CA) at varying loading levels. Structural, thermal, mechanical, and water resistance properties of the bioplastic composites were characterized. Fourier transform infrared spectroscopy (FTIR) evidenced the esterification of starch by CA and the formation of hydrogen bonds among starch, fibers, and CA. Scanning electron microscopy (SEM) micrographs indicated that the fibers below 10 wt% contents can disperse uniformly in the composites, while higher contents of fibers contributed to the starch retrogradation or fiber aggregates. The addition of CA promoted the compatibility between fibers and starch effectively. The incorporation of fibers enhanced the melting temperature and thermal stability of the composites, while the effect of CA on thermal properties depended on its loading levels. The incorporation of fibers or CA improved the tensile strength of the composites significantly and enhanced the water resistance moderately. 3 wt% CA caused the decomposition of starch and deteriorated these properties of the composites. The green bioplastic composites represented a potential replacement for non-biodegradable plastics. Graphic abstract