Influence of functionalized exfoliated reduced graphene oxide nanoparticle localization on mechanical, thermal and electronic properties of nanobiocomposites

This article reports unique microstructural development and enhanced mechanical and thermal properties of a biodegradable polylactide (PLA)/poly(ε-caprolactone) (PCL) blend through selective localization of functionalized thermally exfoliated reduced graphene oxide (f-TERGO) particles in the dispersed PCL phase. We used batch melt-blending to produce the PLA/PCL/f-TERGO composites with matrix of PLA and PCL. With the addition of 0.05 and 0.1 wt% f-TERGO to the polymers, there was no significant change in the blend morphology; however, at 0.25 wt% f-TERGO loading the size of the dispersed phase increased. The impact strength increased from 6 kJ/m² for neat PLA to 10 kJ/m² for the 0.1 wt% f-TERGO composite, whereas the elongation-at-break increased from 5% for neat PLA to 90% for the 0.05 wt% f-TERGO-filled composite. The thermal conductivity of the composites moderately increased with f-TERGO addition, which was associated with an increased number of nucleation sites in the f-TERGO-containing composites, homogenous spherulite growth, and increased crystallization temperature of the PCL phase. Unlike TERGO, f-TERGO addition did not increase electrical resistivity, clearly due to the surface functionalization. This study demonstrates the possibility of enhancing the toughness, melt-viscosity, and thermal conductivity of PLA by blending it with PCL and f-TERGO.