Chemical analysis and EHL characterization of several synthetic lubricants

The development of synthetic lubricants in recent decades has been the result of a concerted effort between engineers and chemists to formulate the ideal rheological-tribological properties for a multitude of applications. This has expanded the range of polymeric lubricants available to designers from a relatively small group of natural hydrocarbon polymers to a broad selection of natural and synthesized hydrocarbons as well as several synthesized silicone based polymers. Many desirable properties of lubricants such as film forming abilities and chemical stability are based on the molecular properties of polymers used therein. This study examines the chemical and physical properties of certain silicone lubricants and focuses on how molecular length, weight and features such a phenyl/methyl branching influence the performance of the lubricant. It is found that increasing polymer length and phenyl branches contributes to increased viscosity and film forming ability. A similar albeit less desirable relationship is also observed in the coefficient of friction in elastohydrodynamic lubrication regimes.