Studies on the application of poly(acrylate‐co‐maleic anhydride) amides with N‐phenyl‐p‐phenylenediamine as multifunctional lube additives

Three polymeric amides were developed by utilizing three acrylates of alkyl chain C‐8, C‐12 and C‐18 and maleic anhydride via polymerization pathway followed by successful coupling with N‐phenyl‐p‐phenylenediamine to give poly(Ac8‐co‐MA)PPA, poly(Ac12‐co‐MA)PPA and poly(Ac18‐co‐MA)PPA. After successful molecular identification, application as lubricant additives as viscosity index improver, pour point depressants, deposit control agents and anticorrosion was done in polyol based synthetic lube oil. A rheological study was also carried out. For comparative performance evaluation, the commercial additives were also taken. Because of the diphenyl moiety in the molecular structure, additives showed the DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) radical scavenging activity. Poly(Ac18‐co‐MA)PPA additive at a high concentration of 5000 ppm, the viscosity index increased from 179 to 217 while the pour point decreased from −18 to −30°C. As far as the detergent dispersant property is concerned, poly(Ac18‐co‐MA) reduced the coking value from 87.5 to 13.2 mg, while % dispersancy increased from 20% to 42%. Three polymeric multifunctional additives [poly(Ac8‐co‐MA)PPA, poly(Ac12‐co‐MA)PPA and poly(Ac18‐co‐MA)PPA] were prepared by polymerization pathway and evaluated as VII, PPD, detergent‐dispersants, antioxidants and corrosion inhibitors. Standard test methods (ASTM) were used to examine the additive performance. Longer alkylated amide polymer viz. poly(Ac18‐co‐MA)PPA reveals the best activity due to the solvation effect at 5000 ppm.