Comparison of Carboxymethyl Cellulose (CMC) and Microcrystalline Cellulose (MCC) as Filler for Sago/Citric Based Bioplastic by Response Surface Methodology

Bioplastic material has emerged as one solution to the environmental problem caused by commercial plastic. Several raw materials have been used for bioplastic production, such as cassava, potato, and sago starch.  This research focused on studying the effect of fillers and plasticizers variation to tensile strength and its morphology by using sago starch/citric acid-based bioplastic. The comparison of sorbitol and glycerol role as the plasticizer and microcrystalline cellulose and carboxymethyl cellulose as fillers were observed. This study was conducted by mixed and heated sago starch and fillers together. Then, citric acid and plasticizers were employed in the mixture solution. Next, the mixture was heated for 24 h then molded. The concentration of fillers, plasticizers, and citric acid were used as an independent variable which the interaction among them were investigated using response surface methodology (RSM) based on Central Composite Design (CCD). ASTM D822 evaluated tensile strength, and the morphological analysis was observed by using scanning electron microscopy (SEM). The results showed that the highest tensile strengths were 8.23 MPa for the glycerol and CMC process and 15.84 MPa for the sorbitol and MCC process. It was found that sorbitol and microcrystalline cellulose (MCC) increased the value of tensile strength twofold more than other fillers and plasticizers. As for the response surface method, the results describe the significant interaction between plasticizer and filler. It showed the tendency of increasing the concentration of fillers and citric acid decreased the tensile strength.