FUNCTIONALIZED POLYMERS FOR LUBRICANTS

Specialty polymers are used as viscosity index (VI) improvers to contr ol the viscosity-temperature characteristics of a lubricating oil. The polymer properties are critical to the physical characteristics of th e final lubricant and its engine performance. The structure of the pol ymers can be modified to produce multifunctional additives which not o nly improve the VI but also impart other properties to the oil such as dispersancy and/or antioxidancy and/or antiwear properties. Such VI i mprovers are based on polymers containing very small amounts of pendan t polar functionality. Ethylene-propylene copolymers (EPs) and their d erivatives are widely used as VI improvers. The structure of the polym er, i.e., the average composition, crystallinity, the arrangement of t he monomers along the chain, and molecular weight distribution are of great importance. The effect of composition and crystallinity of EPs o n their viscosities in hydrocarbons has been studied. We have also stu died the functionalized EPs by the fluorescence probe method and molec ular modeling.