Effect of Graphene Oxide Reduction with L-Ascorbic Acid on Electrical Conductivity and Mechanical Properties of Graphene Oxide-Epoxy Nanocomposites

Abstract

In this study, conductive nanocomposites were prepared by dispersing two different types of nanoparticles in the epoxy resin (bisphenol A) matrix. In the first case, Graphene Oxide (GO) was used as the nanoparticle filler, while in the second one, reduced graphene oxide (rGO), which was made using L-ascorbic acid as the reducing agent, was dispersed in the epoxy base. For this purpose, different weight percentages of nanoparticles including 0.25, 0.5, 1, and 2 % were selected to be examined. The prepared samples then were compared with the blank sample in terms of electrical conductivity and mechanical properties involving tensile strength and elastic modulus. According to FT-IR and XRD analyses, it was observed that oxygen functional groups were reduced substantially for the rGO. However, in this case, owing to the transformation of the binary system from polar-polar to polar-nonpolar, rGO could not disperse well in the epoxy matrix. To address this problem, nonylphenol polyethylene was used as a surfactant to provide more suitable dispersion in the epoxy. Results also demonstrated that the electrical conductivity of rGO-epoxy nanocomposite increased dramatically in comparison with both neat epoxy samples and epoxy/GO ones, and the maximum conductivity of 3×10-4 S/m (8 orders of magnitude higher than the pristine epoxy resin) was achieved at the rGO percentage of 2%. In addition, mechanical properties (e.g. tensile strength and elastic modulus) were superior in the case of GO and rGO nanocomposites in comparison to that of the blank sample, except for the 2 wt% rGO. Therefore, the best-prepared nanocomposite was the 1wt% rGO sample which improved the electrical conductivity up to 7 orders of magnitude. Likewise, tensile strength and elastic modulus modified 21% and 34 %, correspondingly relative to the neat epoxy sample.

Keywords

• conductive nanocomposite
• l-ascorbic acid
• reduction
• epoxy
• graphene