Characteristics of bio-plastic composites from the modified cassava starch and konjac glucomannan

The production of bio-plastic from modified cassava starch and konjac glucomannan has been widely and dependently developed but still demonstrated the characteristics that do not meet international standards. So that needs to be developed bio-plastic composites from both the material. This study aims to know the effect of a ratio variation of the modified cassava starch – konjac glucomannan and the concentration of acetic acid to characteristics of bio-plastic composites, determine a ratio of the modified cassava starch – konjac glucomannan and the concentration of acetic acid solution to produce bio-plastic composites with the best characteristics. This study used a Factorial Randomized Block Design with two factors. Factor I is a ratio of the modified cassava starch – konjac glucomannan, which consists of 5 levels namely 100:0, 75:25, 50:50, 25:75, and 0: 100. The factor II is the concentration of acetic acid which consists of 5 levels, namely 0; 0.5; 1.0; 1.5 2.0%. Each treatment combination was grouped into 4 blocks based on the time of the process of making bio-plastic composites, so that there were 100 experimental units. The data obtained were analyzed of variant and followed by Duncan’s multiple comparison tests. The variables observed were tensile strength, elongation at break and Young’s modulus, swelling, the degradation time of bio-plastic composites, surface profiles and functional groups. The results showed that a ratio of the modified cassava starch – konjac glucomannan, the concentration of acetic acid and its interaction had a very significant effect on tensile strength, elongation at break, Young’s modulus, swelling and the degradation time of bio-plastic composites. A ratio of the modified cassava starch – konjac glucomannan = 75:25 with 1% acetic acid concentration produced the best bio-plastic composites with the characteristics : tensile strength of 1997.40 MPa, elongation at break of 8.90%, Young’s modulus of 22442.70 MPa, swelling of 10.40% and the degradation time of 6.33 days. The surface profiles of bio-plastic composites in longitudinal appearance shows the presence of regular wave forms along with air cavities or regular pores. Bio-plastic composite profiles in transverse appearance shows the arrangement of fibers in the form of regular nets and smooth cross links. These bio-plastic composites contain functional groups: (O-H), (C-H), (C-N), (C-O), (C-C), (C=C), (N-H), -(CH2)n and (C=O).