This reduced average viscosity has been shown to be an effective formulation strategy for the improvement of overall operational efficiencies in automotive and industrial lubricant applications. One strategy then, to improve overall efficiency, has been to use lubricants that have been designed to have weak viscosity-temperature dependence and a reduced average viscosity across their entire operational temperature range. While these minimum viscosity requirements at higher operating temperatures are critical for maintaining durability and efficiency, at lower operating temperature regimes, the natural increase in the lubricant’s viscosity is counterproductive to overall operational efficiency. To maintain the load-bearing characteristics which lead to this fluid film, the lubricant must maintain a minimum viscosity across its entire range of operating conditions, including those occurring at high temperatures and high shear environments. In this way, frictional penalties due to solid-to-solid contacts are greatly reduced by hydrodynamic lubrication. Interactions between polymer molecules that can be controlled by the choice ofĪ powerful and widely-applied strategy for reducing frictional losses between two moving mating surfaces is to separate the surfaces by means of lubricating oil. Macromolecules on VI should be complemented with the idea of hydrodynamic
This finding implies that even in theĭilute regime, the coil-expansion theory used to explain the effect of In this paper, we show that the dependence of VI on the non-dimensionalĬoncentration c / c * (or c ) can be presented in a form of masterĬurve with shift factors proportional to K M that decreases Interactions of polymer chains at actual polymer concentrations in lubricating While the intrinsic viscosity is associated with the volume of macromolecules at infiniteĭilution, the parameter K M reflects the hydrodynamic We establish structure property relationships for these PAMAs, specificallyĪnd Martin interaction parameters K M relate to VI and SSIĬharacteristics. Then, expanding on previous methodology reported in the literature, Polymerization in a family of PAMAs with varying lauryl, hexyl, butyl, ethyl,Īnd methyl groups. In this report, we use reversible addition-fragmentationĬhain transfer (RAFT) polymerization to precisely target identical degrees of Methacrylates) (PAMAs) are routinely used to control these properties inįully-formulated liquid lubricants. A variety of oil-soluble polymers, including poly(alkyl Temperature-viscosity dependency and resistance to product degradation,
Viscosity index (VI) and shear stability index (SSI)Īre standard methods used in the lubricant industry to determine
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