Modeling of electrical conductive graphene filled epoxy coatings

Abstract

Electrical conductive coatings were prepared by incorporating various fractions of graphene nanoplatelets (GNPs) into epoxy resin, i.e. 0–2.5 wt.%. High stability of GNPs as dispersed form in chloroform and their uniform distribution in epoxy matrix were proved by UV–vis spectroscopy, turbidimetry and optical microscopy techniques. SEM images were also used to check the GNPs state in each step of fabrication. All epoxy coatings underwent electrical conductivity measurement, the conductivity of epoxy coating increased 13 orders of magnitude by addition of 2.5 wt.% GNP. Through this experiment, GNP fraction as low as 0.5 wt.% was defined as percolation threshold. Four types of conductivity models were analyzed (i.e. Kirkpatrick and Zellen, GEM, updated Mamunya and additive model) to select the most precise one for predicting epoxy/GNP coating conductivity behavior. It was finally demonstrated that the additive model presented the best correlation with the experimental data. We also revised the additive model parameters to further promote its accuracy. Finally, mechanical properties of coatings studied by DMTA demonstrated relative increase of about 100% in storage modulus of coating at percolation threshold with respect to neat coating, approving the desired conductivity and mechanical attributes for graphene containing epoxy coating.