Starch granules containing amylopectin-rich fractions like sago starch may remain insoluble and undamaged decreasing properties of the film. The aim of this study is to characterize native sago starch films prepared using ultrasonication. An ultrasonication probe was used during gelatinization for 2.5, 5, and 10 min respectively. Ultrasonication decreases the incomplete gelatinized granules resulting in a film with a more compact structure, and lower moisture vapor permeability than non-treated film. The longest duration resulted in a film with the highest transparency, and the highest thermal resistance. The duration for 5 min increased tensile strength of the film by 227%, and its moisture absorption decreased by 29.83% compared to non-sonicated film. After ultrasonication for 10 min, melting temperature increased by 7% in comparison to non-sonicated film. This work promotes a simple method to improve the tensile and physical properties of starch based film.

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Abstract:In this study, the isolation and characterization of nanocellulose from pineapple leaf fibers (PLF) were carried out. Chemical pretreatment included pulping, bleaching, and acid hydrolysis to remove lignin, hemicellulose, and extractive substances were conducted. This was followed by high-shear homogenization and ultrasonication to produce nanocellulose. Morphological changes to the PLF due to treatment were investigated using scanning electron microscopy (SEM). This showed that the PLF had a diameter of 1-10 µm after high-shear homogenizing. Transmission electron microscopy (TEM) indicated that the nanofibers after ultrasonication for 60 min showed 40-70 nm diameters. Particle size analysis (PSA) indicates that the fibers had an average diameter of 68 nm. Crystallinity index was determined by X-ray diffraction (XRD) and had the highest value after acid hydrolysis at 83% but after 60 min ultrasonication, this decreased to 62%. Meanwhile, Fourier transform infrared (FTIR) spectroscopy showed there was no chemical structure change after acid hydrolysis. The most significant finding from thermal gravimetric analysis (TGA) is that the higher degradation temperature of nanofibers indicates superior thermal stability over untreated fiber. These results indicate that PLF waste could become a viable source of commercially valuable nanocellulose.

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