Influence of Polyalkylmethacrylate VII on Boundary Film Formation,Friction,Wear and Efficiency of Lubricants

1 Influence of PAMAon Boundary Fil mFormation and Friction1.1 Experi mental methodsUltra-thin optical interferometry has been used tostudy thinlubricating fil ms for more than a decade and theexperi mental details of this technique have been reportedpreviously1].The principle of the test setup is shown inFigure1.A polished steel ball is loaded and rolled againstthe flat surface of a glass disc that is coated with a thinsemi-reflecting chromiumlayer and a silica spacer of about500nmthickne…

Influence of Polyalkylmethacrylate VII on Boundary Film Formation,Friction,Wear and Efficiency of Lubricants

Polyalkylmethacrylates(PAMAs) are well-known as viscosity index improvers and dispersant boosters.This paper shows that PAMAs are able to adsorb from oil solution on to metal surfaces,to produce thick,viscous boundary films.These films enhance lubricant film formation in slow speed and high temperature conditions and thus produce a significant reduction of friction.A systematic study of this phenomenon has made use of the highly flexible nature of PAMA chemistry.A range of dispersant and non-dispersant polymethacrylates has been synthesized.The influence of different functionalities,molecular weights and architectures on both boundary film formation and friction has been explored using optical interferometry and friction-speed charting.From the results, guidelines have been developed for designing PAMAs having optimal boundary lubricating properties.Through their ability to form boundary films PAMAs can significantly contribute to reduce wear in engine,gear and hydraulic lubrication.As a consequence of their viscometric and tribological performance PAMAs can furthermore improve fuel and energy efficiency in different,namely engine and hydraulic applications.Extensive work is currently conducted in the lubricant industry to develop engine oils with lower sulfur,phosphorus and metal content(low SAPS) and to optimize their frictional properties through the use of friction modifiers or synthetic base stocks.We have investigated the contribution of PAMA viscosity index improvers and boosters to improve fuel economy and to reduce wear levels.This paper reports our efforts to develop a new range of PAMAs that have been optimized in terms of composition,architecture,molecular weight and functionality and which can be used in low viscosity,low SAPS formulations to help meet the stringent requirements of modern engine oils.