Study of alkyl acrylate-co-maleic anhydride-based novel amide copolymers as multifunctional lubricant additives

Three novel multifunctional additives (MFAs), poly(alkyl acrylate-co-maleic anhydride)-based amide copolymers, were synthesized by the reaction between intermediate alkyl acrylate-co-maleic anhydride and three different amines, viz. octylamine (MFA 1), dodecylamine (MFA 2), and octadecylamine (MFA 3). Additives were successfully prepared by the polymerization route using benzoyl peroxide (Bz₂O₂) as a free radical initiator. Analytical techniques such as Fourier transform infrared, nuclear magnetic resonance, and gel permeation chromatography were used to characterize the synthesized polymeric compounds. Polyol was taken as reference base oil for performance evaluation of the synthesized polymers as multifunctional additive for viscosity index improver, pour point depressant, anti-wear, anti-friction, detergent–dispersant, and anti-corrosion properties. MFA 1 reflected the best performance as detergent–dispersant and anti-corrosive additive with observed increment of ~ 48% and ~ 54%, respectively, in comparison with blank polyol. MFA 3 showed the best viscosity index improving property which enhanced the viscosity index of polyol base oil from 191.85 to 250.45 at 3000 ppm. It also showed best tribological performance in 3000 ppm concentration at which the average wear scar diameter and average friction coefficient values decrease to 482 µm and 0.0823 from the 690 µm and 0.1276 for blank polyol.