Optimizing Conductivity and Strength of Biodegradable Polymer Graphene Nanoplatelet Nanocomposites via 3D-Printing

Graphene is an incredibly tensile allotrope of carbon with high thermal and electrical conductivity. By blending GNP with biodegradable and non-corrosive polymers, graphene's properties, ductility, and ease of processing can be exploited. An important drawback though is the reduced ductility that occurs when high concentrations of GNP are used. Here we demonstrate how the addition of a second polymer component could be used to engineer blends that achieve the same high thermal and electrical performance, with reduced GNP content. The higher ductility which results also allows this nanocomposite to be extruded into filaments for FDM printing, and if this component is also degradable, the composite is environmentally sustainable and does not introduce toxicity if recycled. For the work presented here, we chose PLA as the second polymer, which is immiscible with iPP and where the interfacial energy with GNP was much higher than that of the particles with iPP. Hence when the two polymers are blended the GNP are expected to aggregate entirely in the iPP phase. This serves to increase the local density of GNP in the iPP phase, achieving percolation at much lower overall concentrations. Based on the results, GNP concentration is directly correlated with increasing electrical and thermal conductivity. At 15% GNP, the maximum electrical conductivity recorded was at the 40/60 iPP/PLA ratio, around 8 S/m at room temperature. At 20% GNP, the maximum conductivity was at the 30/70 iPP/PLA ratio, around 18 S/m. This Study indicates a similarity in the properties of polymer blend to the properties of expensive elements of semiconductors. Optimizing the environmentally beneficial and durable properties of the polymers with electrically and thermally efficient GNPs yields exciting prospects for more sustainable technology and electronic systems.