Abstract
Six copolymers based on acrylates were used as viscosity index improvers [1]. The effect of these copolymers on the rheological behavior such as viscosity thinning or thickening has been studied. A rheological study was carried out to SAE 30 base oil before and after adding the viscosity index improvers with different concentrations (1, 2, 3% wt). Brookfield rheometer model (DV-III+) was used with different shear rates and at different temperatures (40, 60, 100 ˚C), for characterization of the enhanced lubricant. It was noticed that Free- additives Base oil exhibits a Newtonian behavior at all temperatures, on the other hand; all enhanced samples exhibit a weak non-Newtonian behavior that disappears with increasing either temperature or shear rate or both of them. The effect of temperature on specific viscosities of the blends under different shear rates was studied to determine the efficiency of viscosity index improvers and record its mechanism of action at different shear rates and temperatures.