Characteristics of starch-based bioplastic composites in the ratio variations of the polysaccharide mixture

characteristics. This study used a randomized block design with the following polysaccharide ratio treatment: starch:glucomannan = 25:75, starch:glucomannan = 50:50, starch:glucomannan = 75:25, starch:chitosan = 25:75, starch:chitosan = 50:50, starch:chitosan = 75:25, starch:carrageenan = 25:75, starch:carrageenan = 50:50, starch:carrageenan = 75:25, starch:alginate = 25:75, starch:alginate = 50:50 and starch:alginate = 75:25. Each ratio grouped into 3 times of the process of making bioplastic composites, so that there were 36 experimental units. The results showed that the ratio of the polysaccharide mixture had a very real or significant effect on tensile strength, elongation at break, Young modulus, water vapor transmission rate (WVTR) and swelling but has no effect on biodegradation time. The mixture ratio of starch:carrageenan = 25:75 produced the best composite characteristics with tensile strength of 27.35 MPa, elongation at break of 18.01%, Young modulus of 151.94 MPa, WVTR of 7.19 g/m2 /hr, swelling of 172.62%, biodegradation time of 8.33 days, crystalline content of 20.80% and amorphous 79.20%, weight loss at maximum evaporation temperature (72.56oC) of 4.83% and maximum temperature of degradation (221.01oC) of 30.15%. This bioplastic composite shows the presence of even cubical grains with few pores between the grains in the longitudinal position surface profile and shows sharp and layered peaks and troughs in the transverse position and contains functional groups O-H, C=C (alkene, aromatic), C-H and C-O (alcohol, ether). The characteristics of bioplastic composites such as tensile strength have met the Indonesian national standard (SNI), elongation at break has met PCL plastic standards from the UK and biodradation time has met PLA plastic standards from Japan and PCL from the UK.