Production of Cassava Starch Composite as a Sustainable Alternative for Plastics

Abstract

Production of petroleum-based non-biodegradable plastic is increasing all over the world while making a huge threat to the environment. As a solution, in the past few decades, there has been a marked advance in the development of bio-plastics from renewable resources mainly from starch-based materials for different applications. The aim of this study was to develop a bio-plastic from Cassava (Manihot esculenta) and reinforce with materials to improve the tensile properties with respect to HDPE towards industrial applications. Initially, starch was extracted from the Cassava tubers and using the ‘doctor-blade method’, plastic films were prepared with various formulations. By varying percentages of Citric acid and Phosphoric acid, a series of plastic films were made and to optimized tensile strength with to respect HDPE. An optimized recipe for plastic films containing Cassava starch, Citric acid and, Phosphoric acid was selected to incorporate reinforcing modifiers such as Graphene Oxide (GO) and r-GO. GO for reinforcement was produced using Tour’s method. The chemical and mechanical properties of the produced films were recorded and analysed using Fourier Transform Infrared Spectrometer (FTIR) and tensile strength tester respectively. Additionally, an ANOVA was also performed for all the tensile strength results, at a confidence level of 95% to select the optimized recipe. The FTIR spectroscopy revealed an appearance of ester carbonyl peak at 1700-1750 cm-1 indicating that the hydroxyl group of starch has been cross-linked with Citric acid forming an ester group. Tensile strength results indicated that the strength of the cross-linked films have also increased beyond the reported value for HDPE, which is 20 MPa. The tensile strength and FTIR spectroscopy results obtained for different films concluded that the optimized Citric acid percentage as 3%(w/w) with 1%(w/w) Phosphoric acid. The ANOVA indicated that there is a statistically significant effect on tensile strength at 95% confidence level from the interaction between Phosphoric acid and Citric acid. Time limitation and waiting period for certain results restricted the fast progress of the project and therefore had to limit the original scope. In conclusion, plastic films containing 96% Cassava starch were prepared to match the tensile strength of HDPE and some preliminary studies of reinforcement were carried out with GO and r-GO. Further studies to show the permeability, biodegradability and solubility should be carried out with these plastic films to optimize towards industrial applications.