Characteristics of Bioplastic Composites in Variation of the Ratio of Gadung Starch (Dioscorea hispida D.) - Glucomannan and its Gelatinization Temperature

Abstract

This study aims to determine the effect of variations in the ratio of gadung starch (Dioscorea hipida D.) - glucomannan and their interaction on the characteristics of bioplastic composites and to determine the ratio  of gadung starch (Dioscorea hipida D.) - glucomannan and its gelatinization temperature which gives the best  characteristics of bioplastic composites. This study used a factorial randomized block design (RBD) with two  factors. The first factor is the variation in the ratio of the gadung tuber starch - glucomannan which consists  of 3 levels, namely (60:40), (50:50), (40:60). The second factor is the gelatinization temperature which consists  of 3 levels, namely 75 ± 1oC, 80 ± 1oC 85 ± 1oC. Each treatment was grouped into 2 based on the time of the  manufacturing process so that 18 experimental units were obtained. The variables observed were tensile  strength, elongation at break, elasticity, and biodegradation time. The data obtained were analyzed of variant  and continued with the HSD Tukey. The results showed that the ratio of gadung - glucomannan starch,  gelatinization temperature, and their interactions had a very significant effect on tensile strength, elongation  at break, and elasticity but it did not significantly affect the biodegradation time. The ratio of gadung tuber  starch - glucomannan (60:40) with a gelatinization temperature of 85 ± 1oC produced the best bioplastic  characteristics with a tensile strength value of 4.4 MPa, an elongation at break of 9.5%, and elasticity value  of 22.390 MPa and resulted in a degradation time of 7 days. 2 variables meet the standards, namely: the  extension when the bioplastic composites have broken up has met the SNI plastic standards and biodegradation  has met the international plastic standard ASTM 5336.