Graphite nanoplatelets (GNP) have recently become a commercially available alternative to graphene that has been widely studied as an additive to improve polymer properties. In particular, their use in improving the thermal properties of composites has many applications for the electronics industry. Expanded graphite (EG) is commonly used as starter material for the production of these nanoplatelets. However, the exfoliation of EG into nanoparticles typically involves the use of solvents, which are difficult to remove, and includes sonication which is time consuming and can cause defects in the platelets. Here, a commercially available, high-shear mixer is used to rapidly exfoliate EG in epoxy resin. The cured composites were measured for improvements in thermal conductivity and characterized using scanning electron microscopy and Raman spectroscopy.