3. Results and discussion
The scanning electron micrographs are illustrated in Figure 1 for the graphene that solves the problems regarding insufficient exfoliation of the graphite powder and deterioration in the electrical conductivity and thermal conductivity. Graphite is a stack of graphene sheets bound by van der Waals interactions, each graphene layer being made ofsp 2 carbons distributed in a hexagonal crystal structure. Graphene has superior mechanical, electrical, and thermal properties. In bottom-up methods to produce graphene, for example, chemical vapor deposition, graphene is synthesized. In top-down methods, for example liquid-phase exfoliation, graphene sheets are separated from bulk graphite material. The bottom-up approach produces low quantities with high quality and large flakes. The top-down approach using graphite is low in cost and yields a high concentration of suspended flakes, but fabricates limited-size sheets with a low yield of mono-layer graphene. Existing commercially available graphene products usually contains precipitates of graphene due to the presence of thick layers of graphene and are not stable. The method of the exfoliation of graphene from graphite using multilayer coextrusion is described herein. Graphite is dispersed within a first processing material, and the first processing material and a second processing material are co-extruded through a plurality of series coupled layer multiplication dies to exfoliate graphene from the graphite. The graphene is separated from the resulting multi-layered material. Graphite flake and expanded graphite may be dispersed within the first processing material. The process uses an organic solvent and silica under high pressure sheer force to create a liquid intermediate containing thin layers of graphene that allows for easy dispersion of graphene in a liquid organic solvent system. High sheer processing of graphene and silica together in a liquid organic solvent system result in stable graphene platelets. During the process, thick layers of graphene can break down to smaller layers of graphene that is more usable. The silica forms a gel simultaneously as graphene platelet multiple stacks are sheered into smaller platelet stacks through the organic solvent carrier. The small platelet stacks are dispersed in the gel and held by the network of the gel stably. In the process, both a graphene raw material and silica are mixed in an organic solvent to form a liquid precursor. Preferably, the graphene raw material is a graphene powder. The graphene raw material may be obtained commercially. Commercially available graphene usually contains thick layers. Thus, when commercially available graphene is used as an additive or is added to a liquid product, the commercially available graphene may precipitate in the liquid product.