Viscometric and Wear Performance of Methacrylate-based Lubricants

Methacrylate based lube oil additive of three different kinds viz, one homopolymer (polyhexadecyl methacrylate [PHDMA]) and two of its copolymers (HDMA-1-decene and HDMA-styrene) have been synthesized, characterized and investigated for their viscosity modifier (VM), antiwear (AW), and thickening performance at different concentrations in two different base oils. The VM properties in terms of viscosity index (VI), the AW properties through determination of wear scar diameter (WSD) using a four ball wear tester and thickening (i.e., rise in oil viscosity due to added polymer at a given polymer concentration was studied). The polymers studied have been found to show VM and AW properties under the experimental conditions. At a given polymer concentration thickening was found to increase in the order PHDMA-styrene > PHDMA-1-decene > PHDMA. The intrinsic viscosity, a measure of polymers hydrodynamic volume, showed a higher value in lower viscosity base stock, as compared to the higher viscosity oil in the case of homopolymer and PHDMA-1-decene copolymers. The decrease in viscosity with temperature followed the order PHDMA > PHDMA-1-decene > PHDMA-styrene; indicating a better viscosity index for the styrene copolymer (PHDMA-styrene).