Research Papers: Lubricants

The Viscosity of Polyalphaolefins Mixtures at High Pressure and Stress

[+] Author and Article Information
Scott Bair

Center for High-Pressure Rheology,
George W. Woodruff School of
Mechanical Engineering,
Georgia Institute of Technology,
Atlanta, GA 30332-0405
e-mail: scott.bair@me.gatech.edu

Samuel Flores-Torres

Products Research and Technology Department,
ExxonMobil Research and Engineering,
600 Billingsport Road—Room #48-104,
Paulsboro, NJ 08066-0480
e-mail: samuel.flores-torres@exxonmobil.com

Contributed by the Tribology Division of ASME for publication in the JOURNAL OF TRIBOLOGY. Manuscript received April 13, 2018; final manuscript received August 3, 2018; published online October 11, 2018. Assoc. Editor: Wang-Long Li.

J. Tribol 141(2), 021802 (Oct 11, 2018) (7 pages) Paper No: TRIB-18-1154; doi: 10.1115/1.4041124 History: Received April 13, 2018; Revised August 03, 2018

Understanding the pressure and shear dependence of viscosity is essential to an understanding of the mechanisms of film forming and friction in concentrated contacts. The blending of different molecular mass polyalphaolefins (PAOs) may permit the formulator to arrive at a desired combination of film thickness and friction. The viscosities of PAO base oils and their blends were measured versus temperature, pressure, and shear stress to 1 GPa in pressure. The Grunberg–Nissan mixing rule, with effective mole fractions, provides an excellent mixing rule for the temperature and pressure-dependent low-shear viscosity. This work provides the first look at a possible mixing rule for the non-Newtonian response of mixtures of base oils.

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Bair, S. , Fernandez, J. , Khonsari, M. M. , Krupka, I. , Qureshi, F. , Vergne, P. , and Wang, Q. J. , 2009, “ Letter to the Editor,” Proc. Inst. Mech. Eng., Part J: J. Eng. Tribol., 223(4), pp. 1–2. [CrossRef]
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Bair, S. , and Qureshi, F. , 2003, “ The High Pressure Rheology of Polymer-Oil Solutions,” Tribol. Int., 36(8), pp. 637–645. [CrossRef]


Grahic Jump Location
Fig. 1

The EHL friction shear stress versus apparent shear rate from experiment and versus slide to roll ratio from a simple calculation

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Fig. 2

The pressure–viscosity response of the liquids of Fig. 1 from the correlations in Ref. [17]

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Fig. 3

The viscosity of the blend of PAO-4 with PAO-600 compared with the improved Yasutomi correlation

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Fig. 4

The viscosity of the blend of PAO-4 with 25% PAO-100 comparing the mixing rule with experiment

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Fig. 5

The viscosity of the blend of PAO-4 with 25% PAO-600 comparing the mixing rule with experiment

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Fig. 6

Mixing curves for PAO-4 with effective mole fraction of PAO-100

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Fig. 7

The shear-dependent response of PAO-100

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Fig. 8

The shear-dependent response of PAO-4 + 50% PAO-100

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Fig. 9

The shear-dependent response of PAO-600

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Fig. 10

The shear-dependent response of PAO-4 + 50% PAO-600

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Fig. 11

Comparing the shear-dependent response of mixtures of PAO-4 with PAO-100

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Fig. 12

Comparing the shear-dependent response of mixtures of PAO-4 with PAO-100

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Fig. 13

Mixing curves for the reduced viscosity of PAO-4 + PAO-600 at three values of shear stress



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