Bio-plastic composite characteristics of the modified cassava starch-glucomannan in variations of types and addition of fillers

The aim of this research was to investigate the effect of variations in filler types, the amount of fillers and their interactions on the characteristics of bio-plastic composites from modified cassava starch-glucomannan, and determine the type and amount of fillers that produce the best bio-plastic composite characteristics of modified cassava starch-glucomannan. This research applied a randomized block design with factorial experiments using two factors consisted of the type of filler (ZnO, CMC and chitosan) and the amount of fillers (0, 0.2, 0.4, 0.6, 0.8 and 1.0 g), with the total of 18 combination treatments. Each combination treatment was grouped into 4 based on the processing time of making bio-plastic composites. The variables observed were tensile strength, elongation at break, Young’s modulus, swelling, degradation time of bio-plastic composites, surface profiles using scanning electron microscopy (SEM) and functional groups using FTIR spectrometers. The results showed that the type, the amount of fillers and their interactions had a very significant effect on tensile strength, elongation, Young’s modulus, swelling, and degradation time of bio-plastic composites from modified glucomannan cassava starch. Bio-plastic composites from modified cassava-glucomannan starch using ZnO with the addition of 0.6-1.0 g had the best characteristics compared to others with tensile strength values reaching 2012.45-2022.23 MPa, elongation at break 8.12-8.65 %, Young’s modulus 23.265.32-24,904.31 MPa, swelling 9.52-9.72 %, and degradation time of 6.25 days. Transverse surface profiles showed a smooth wave surface, there were not any holes or pores and visible fibers, while longitudinal surface profiles showed a fewer holes or pores and more smooth surface with not too high waves. In addition, these bio-plastic composites contained functional groups (O-H) and (C-H).