Effect of microcrystalline cellulose on characteristics of cassava starch-based bioplastic

The vast consumption of conventional plastics has a significant effect on the environment that encourages the utilization of natural resources as the raw materials to substitute the petroleum-based plastics. Poor mechanical and moisture barrier properties of starch-based bioplastics causing the development of modified starch-based bioplastics by incorporating reinforcing material. Microcrystalline cellulose (MCC) as a filler of thermoplastic starch shows strong reinforcing ability and high surface area besides its renewability, biodegradability, and affordability compared to nanocellulose. This study aimed to investigate the effect of MCC on the physical, mechanical, and biodegradability properties of starch-based bioplastic. Bioplastic was prepared by melt-mixing starch and glycerol (3:1, w/w) with MCC (5%, 10%, 15%, and 20%, w/w). Density and water contact angle of bioplastic increased with the increase of MCC concentration. Conversely, the moisture content decreased with the increase of MCC concentration. Mechanical properties evaluation showed that bioplastic with the addition of MCC had higher tensile strength than that without MCC where 20% MCC exhibited the highest tensile strength of 16.7 MPa with elongation of 1.31% and Young's modulus of 1.5 GPa. In addition, the decomposition temperature of bioplastic with MCC slightly increased which indicated the higher stability. Cross-section micrograph after tensile test showed that the visible inhomogeneous starch granules decreased with the increase of MCC concentration. FTIR spectra exhibited that the intermolecular interaction in bioplastics occurred through C-H, C = O, C-O-C, C-O-H, and O-H groups. In addition, biodegradability tests of bioplastic showed that the growth of microbes increased in the presence of MCC and microbes covered the bioplastic more than 60% in 21 days. The results showed that MCC performed an important role to enhance the physical, mechanical, and biodegradability properties of starch-based bioplastic.