Preparation of graphene based nanofluids: Rheology determination and theoretical analysis of the molecular interactions of graphene nanoparticles

In this work, graphene-based ten nanofluids were synthesized, and their viscosities were determined. Also, a theoretical analysis of the molecular interactions of graphene nanoparticles is carried out in order to understand the mechanisms affecting the viscosity of nanofluids. Based on the results of experiments, an analytical function that describes the dependence of the relative viscosity on the concentration of graphene nanoparticles was obtained. It was established that the viscosity of the base fluid was affected by the graphene sheet structure. If the graphene sheet possessed an ideal surface, a decrease in the viscosity was observed, but if it contained defects, the viscosity of the nanofluid increased rapidly with increasing concentration. The reason for this behavior of graphene nanofluids was the self-assembly of graphene nanoparticles in the base fluid flow and the formation of ordered clusters from base fluid molecules. In this case, the self-assembly of the graphene nanoparticles was inextricably linked with the formation of the nanoclusters. The struggle between these two processes generated changes in the viscosity of the graphene nanofluids. In the function herein proposed, a new parameter, B/A, was introduced, which made it possible to evaluate the nature of the interactions between the graphene nanoparticles and the base fluid molecules. The reported work is highly useful to design more future graphene-based nanofluids; depending on the requirements.