Bioplastic Properties of Cassava Peel Starch (<i>Manihot esculenta</i>) Influenced by the Addition of Crab Shell Chitosan and Zinc Oxide (ZnO)

Abstract

Cassava shell starch and crab shell chitosan can be used as basic for bioplastics with glycerol and additives such as zinc oxide (ZnO) to improve their mechanical properties. This study used the variables of ZnO percentage and crab shell chitosan mass, which has never been done before. This research process was carried out in several stages, the first was bioplastic synthesis using cassava shell starch, glycerol, and crab shell chitosan with variations of 1 g and 1.5 g with zinc oxide (ZnO) of 3% and 5% of the total mass of starch. The limitations of the research are that the thickness of the tensile test samples is only 0.1-1 mm and the method for making bioplastics is the solution casting method. The second stage is characterization using FTIR to analyze the functional groups of cassava peel starch. Next, observe the morphology on the sample surface using an optical microscope, then a tensile test is carried out to calculate the tensile strength value using the ASTM D882 standard. The results of this research show that the highest tensile strength value for the 1.5 g chitosan and 5% ZnO variation was 10,353 MPa, while the lowest was for the 1 g chitosan and 3% ZnO variation at 4,526 MPa. The elongation value obtained was the highest in the variation of 1.5 g of chitosan and 3% zinc oxide at 10.508%. Meanwhile, the lowest ductility value was found in specimens with variations of 1 g of chitosan and 5% zinc oxide, amounting to 6.716%. The level of water resistance from the swelling test was found to be the highest with the 1.5 g chitosan and 5% zinc oxide variation with water absorption of 23.14%, however, the highest water absorption of 39.36% was obtained with the 1 gr chitosan and zinc oxide variation 3%. Optical microscope testing on the surface of samples of variations of 1.5 g chitosan and 5% zinc oxide showed the best physical properties. Therefore, the addition of reinforcement in the form of chitosan and zinc oxide affects the tensile strength value of the bioplastic film, where the higher the amount of reinforcement used, the higher the strength value produced.