Effect of VI Improver on the In-Service Viscosity of Hydraulic Fluids

Kopko, R. J.; Stambaugh, R. L.

doi:10.4271/750693

Cited by 11 publications

(3 citation statements)

References 21 publications

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“…High-temperature pumping efficiency: High-temperature pumping efficiency is influenced by the role of viscosity in control of internal pump leakage, related to the high-shear-rate viscosity at test temperature [63]. It was also demonstrated that high-shear viscosity directly influences the pumping efficiency of hydraulic fluids as well as being a factor in gear upshifts in automatic transmissions [101].…”

Section: High-temperature Viscositymentioning

confidence: 98%

“…Figure 5.8 shows that engine oils are the mildest application, followed by automatic transmission fluids, hydraulic fluids and rear axle lubricants [63]. Thus, matching shear stability requirements of the application with the selection of VI improver is a key formulation consideration.…”

Section: Overall Viscosity Lossmentioning

confidence: 99%

“…Relationship of molecular weight to SSI for commoner VI Improver applications, redrawn and adapted from [63] Extensive work has attempted to develop laboratory test methods which simulate viscosity loss in various applications, particularly engine oils in field service. Virtually any device which can shear polymers has been used, including sonic oscillators, ball mills, high-speed stirring, diesel injector rigs, pumps in hydraulic circuits, gear rigs, roller bearing devices and a variety of small engines, both motored and fired.…”

Section: Fig 58mentioning

confidence: 99%

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Viscosity Index Improvers and Thickeners

Stambaugh

Kinker

2009

Chemistry and Technology of Lubricants

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The viscosity index of an oil or an oil formulation is an important physical parameter. Viscosity index improvers, VIIs, are comprised of five main classes of polymers: polymethylmethacrylates (PMAs), olefin copolymers (OCPs), hydrogenated poly(styrene-co-butadiene or isoprene) (HSD/SIP/HRIs), esterified polystyrene-co-maleic anhydride (SPEs) and a combination of PMA/OCP systems. The chemistry, manufacture, dispersancy and utility of each class are described. The comparative functions, properties, thickening ability, dispersancy and degradation of VIIs are discussed. Permanent and temporary shear thinning of VII-thickened formulations are described and compared. The end-use performance and choice of VI improvers is discussed in terms of low-and high-temperature viscosities, journal bearing oil film thickness, fuel economy, oil consumption, high-temperature pumping efficiency and deposit control. Discussion of future developments concludes that VI improvers will evolve to meet new challenges of increased thermaloxidative degradation from increased engine operating temperatures, different base stocks of either synthetic base oils or vegetable oil-based, together with alcohol-or vegetable oil-based fuels. VI improvers must also evolve to deal with higher levels of fuel dilution and new types of sludge and also enhanced low-temperature requirements. IntroductionThe 'viscosity index', VI, was an important measure of quality early in the history of the lubricants industry, indicating an oil's potential applications over a wide range of temperatures, described in Section 1.3.2. Pennsylvania grade oils,~100 VI, were the standard against which all others were measured. Hydrogenation and solvent extraction processes were developed to upgrade lubricants from poorer quality crude oils, but the practical VI ceiling for 1930s refinery technology was~110-115.Early workers found that small amounts of rubber dissolved into mineral oil substantially raised VI; however, high levels of unsaturation in the polymer led to oxidation and sludge formation. This was overcome by using a synthetic polymer prepared from gasoline light ends [1], and similar behaviour was later described for 153 R.M. Mortier et al. (eds.), Chemistry and Technology of Lubricants, 3rd edn.,

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Section: High-temperature Viscositymentioning

confidence: 98%

Section: Overall Viscosity Lossmentioning

confidence: 99%

Section: Fig 58mentioning

confidence: 99%

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Viscosity Index Improvers and Thickeners

Stambaugh

Kinker

2009

Chemistry and Technology of Lubricants

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Methacrylic Polymers

Slone¹

2003

Kirk-Othmer Encyclopedia of Chemical Technology

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The commercially relevant and diverse chemistry of methacrylic ester polymers has encouraged their use in a remarkable variety of applications. Within this overview, particular attention is paid to the diversity of properties of methacrylic ester polymers and copolymers, the methods used to produce methacrylic ester polymers with specific properties, and the commercial applications of these materials.

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