Application of semi-in situ liquid exfoliation of graphite to the scalable production of graphene-epoxy nanocomposites

Abstract

Recent advances in graphite wet exfoliation methods include new solvent systems, exfoliation-assisting agents such as pyrophosphate and use of graphite-intercalated compounds. These open new avenues for the scalable and versatile production of graphene/nanographite composites, with the prospect of reducing barriers to the adoption of these materials for real-world applications. This article proposes a semi-in situ exfoliation method in which graphite is exfoliated directly in the epoxy/cosolvent system via high-shear mixing. The method is tested with three different solvent systems: epoxy/acetone; epoxy/N-Methyl-2-pyrrolidone (NMP); and epoxy/NMP/water. Tailoring of mechanical properties of the composites is achieved by adjusting the mixing and centrifugation times and the temperature of the process. The incorporation of graphite microparticles in the composites has a positive influence on strength and flexibility at the expense of rigidity resulting in a 13.4% increase in ultimate tensile strength (UTS) and 73% in elongation at break (εmax) at 0.04 wt% loading. The proposed method also leads to nanocomposites with enhanced properties at low-filler loadings. For example, the 0.01 wt% loading gave a 7.4% increase in Young's modulus, 10.6% in UTS, and 9.1% in εmax. The scalability and versatility of this method make it a promising alternative for industrial production of epoxy/graphene nanocomposites.