Influences of preparation process on electrical conductivity and thermal expansion coefficient of epoxy/graphene nanocomposites

Abstract

In this study, graphene (1 wt% to 5 wt%) is added into epoxy to prepare epoxy/graphene composites by the solution blending method. The process includes the ultrasonication mixing, the mechanical mixing and the isothermal curing. The influences of ultrasonication and curing process on the composite properties are investigated. The microstructure is characterized by AFM (atomic force microscope), SEM (scanning electron microscope), TEM (tunnel electron microscope) and XRD (x-ray diffraction). Based on the experiments, it is concluded that in the ultrasonication mixing, excessive power or operation time may destroy the graphene structure, while insufficient power or operation time may result the aggregation of graphene, both states will lead to the lower electrical conductivity of the composites. Isothermal curing is carried out by a two-step process. By adjusting the parameters, a new fabrication technique is developed. The maximum electrical conductivity of epoxy/graphene composites reaches 2.5 × 10−5 S m−1, which is of great potential in the electrical industry.