Electrolytically Exfoliated Graphene-Polylactide-Based Bioplastic with High Elastic Performance

This work reports an innovative way to prepare biopolymer composite by incorporating graphene (GP) synthesized from electrolytic exfoliation into biodegradable polymer blend (polylactide/epoxidized palm oil: PLA/EPO) based on melt-blending method and studies their physical properties for food packaging and related applications. Multilayer GP structure synthesized by electrolytic exfoliation is confirmed by transmission electron microscopy and Raman spectroscopy, whereas homogeneous GP incorporation in PLA/EPO is verified by scanning electron microscopy and X-ray diffraction. From thermogravimetric analysis and heat deformation temperature (HDT) studies, the decomposition and HDTs of PLA/EPO/GP composites are higher than those of PLA/EPO but are lower than those of pristine PLA and tend to decrease with increasing GP content because of thermal conductivity effect. From standard tensile test, loading of GP in PLA/EPO at an optimal concentration of 0.6 wt % results in higher elongation at break by as much as 52%. The observed additional elongation under a given tension and the corresponding lower tensile strength/Young's modulus may be attributed to lower binding force of materials in the composite because of the presence of relatively weak GP-PLA/EPO interfaces. Moreover, oxygen permeability is found to decrease with increasing GP contents and oxygen permeability is reduced by 40.33% at the GP loading concentration of 0.6 wt %. (C) 2014 Wiley Periodicals, Inc.