Processing and characterization of high content multilayer graphene/epoxy composites with high electrical conductivity

A new processing method was developed to fabricate nanocomposites with a high concentration of multilayer graphene (MLG) in a highly oriented morphology. MLG was first dispersed in a water-based solution with the aid of polyethylenimine. A thin MLG film (paper) having highly in-plane aligned platelets was produced by using a vacuum-assisted self-assembly (VASA) technique. After heat treatment, the MLG paper was immersed in an epoxy/acetone bath at room temperature under vacuum to produce an epoxy impregnated composite. After removal of the acetone, nanocomposites consisting of multiple layers of the MLG paper with up to 27 wt% MLG were fabricated and thermally cured. Scanning electron microscopy (SEM) examination showed that the MLG was well dispersed and aligned, and the MLG paper was fully impregnated with epoxy resin. At 30 degrees C, dynamic mechanical analysis (DMA) results showed that the storage modulus of the resulting nanocomposites with 27.2 wt% MLG reached 10.2 GPa, a 300% increase compared to the neat epoxy. The resulting composites also exhibited electrical conductivity as high as 35 Siemens per centimeter (S/cm). This research demonstrates that the VASA processing technique is capable of fabricating well aligned, high content MLG nanostructured polymer composites with high electrical conductivity. (C) 2015 Society of Plastics Engineers