Tensile and conductivity properties of epoxy composites containing carbon black and graphene nanoplatelets

Abstract

Adding conductive fillers to an insulating polymer matrix produces composites with unique properties. Varying amounts of carbon black (0.33, 0.67, and 1 wt%) and graphene nanoplatelets (5, 10, 15, and 20 wt%) were added to epoxy. In addition, a few carbon black/graphene nanoplatelet/epoxy formulations were also fabricated. The conductivity and tensile properties were determined and analyzed. The single filler composites containing 5 and 10 wt% graphene nanoplatelet and 0.33 wt% carbon black could be used for electrically insulating applications. Composites containing 15 and 20 wt% graphene nanoplatelet could be used for static dissipative applications. The following composites could be used for semi-conductive applications: 0.67 wt% carbon black/epoxy, 1 wt% carbon black/epoxy, 0.33 wt% carbon black/5 wt% graphene nanoplatelet/epoxy, and 0.33 wt% carbon black/10 wt% graphene nanoplatelet/epoxy. At the 95% confidence level, the combination of 0.33 wt% carbon black with 5 wt% graphene nanoplatelet caused the composite electrical resistivity (1/electrical conductivity) to significantly decrease from ∼1015 ohm-cm to ∼104 ohm-cm. It is likely that the highly branched, high surface area carbon black is forming an electrically conductive network with graphene nanoplatelets. Concerning single filler composites, adding ≤1 wt% carbon black did not significantly lower the composite tensile strain; however, adding graphene nanoplatelet did decrease tensile strain and increase modulus. One possible application for the 10 wt% graphene nanoplatelet/epoxy composite is in Polymer Core Composite Conductors for power transmission lines, which need to be electrically insulating, have improved thermal conductivity (increased from 0.2 to 0.3 W/m-K), increased tensile modulus (increased from 2.7 to 3.3 GPa), and good tensile strength (70 MPa) and strain (3.3%).