Synthesis and characterization of bio-degradable starch based graphene nanocomposites

Abstract

Biopolymers with nano-scale fillers based nano-composites have gained significant research interest as an alternative to the conventional plastics. The synthetic plastics are detrimental to health and are a great threat to wildlife due to its low quality degradation and fabrication of biodegradable starch is therefore much needed. Starch, a natural polysaccharide, is considered as one of the most promising biopolymers to the alternatives of fossil resources because it possesses a number of unique specialties such as renewability, abundance, low cost and biodegradability. The physical properties of biopolymer can be improved by incorporating various nano-materials as fillers in the polymer matrix. In this study, Graphene oxide (GO), and Reduced graphene oxide (RGO), derivatives of Graphene, has been used as a nanofiller for plasticized starch (PS) matrix. Biodegradable PS has been extracted from potato and a solution casting technique was used to fabricate GO/PS and RGO/PS nanocomposite. After synthesis, the structural, chemical, mechanical, optical, dielectric and electrochemical properties of the nanocomposite has been studied. The structural properties of the nanocompopsite shows the presence of the same crystal type for PS, GO/PS and RGO/PS. Chemical analysis indicates formation of hydrogen bonding between graphene and PS in nanocomposite. The optical properties shows that incorporation of GO and RGO enhanced the absorbance of the nanocomposite. The tensile strength of PS increased with the amount of graphene nanofiller, proves that GO/RGO had an obvious reinforcing effect on the PS matrix. Furthermore, the dielectric constant of the nanocomposite increases with the filler concentration indicating interfacial and space charge polarization in the nanocomposite. The electrochemical properties shows that incorporation of GO or RGO nanofiller significantly enhance the specific capacitance of the nanofiller. PS/GO (0.5%) shows a higher dielectric constant of almost 5000 and a specific capacitance of 116.5 f/g while PS/RGO (1%) offers a remarkable value in dielectric constant of 60000. The enhanced dielectric constant & specific capacitances of graphene based PS nanocomposite originate from the synergistic effect of PS and graphene. The starch based graphene nanocomposite with improved mechanical, dielectric and electrochemical properties synthesized from a simple, low-cost process will pave a way to the production of economic and bio-friendly energy storage devices.