Rheology of Plastic Lubricants with Additives of Carbon Nanostructures of Various Type

Abstract—Viscosity and the viscosity–temperature dependence are the main criteria for selecting plastic lubricant materials (PLM). The viscoelastic flow of three industrially produced PLM doped with four types of carbon nanostructure (CNS) was assessed. The effect of concentration, type of CNS, and frequency shift (shear and oscillation tests) on this indicator was analyzed. It was shown that the general trend for all the studied systems is a decrease in dynamic viscosity and viscoelastic properties upon the addition of CNS into the basic PLM in the range of shear velocities from 0 to 10 rps and the frequency range from 0.1 to 12 Hz. Shungite carbon nanoparticles have the least effect on the elastic properties of the systems. It was found that the magnitude of the decrease in viscosity of the PLM doped with CNS (additive concentration of 0.5 or 1.0 wt %) depends on the spatial structure of CNS and can be represented by the following sequence: 2D (multilayer oxidized graphene) > 1D (single-walled carbon nanotubes) > 1D (multiwalled carbon nanotubes).