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Thickening Mechanisms of Polyisobutylene in Polyalphaolefin

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Abstract

Molecular dynamics simulations are used to study the effect of polyisobutylene polymer on the viscosity of polyalphaolefin base oil. The Newtonian viscosities of the solution calculated from simulations at 40 and 100 °C agree with rheometer measurements. The simulations are used to investigate three possible mechanisms by which the polymer may increase solution viscosity. The results indicate that neither (1) coil expansion nor (2) polymer–polymer association underlie viscosity enhancement in the case studied here. Measurements of solvent reorientation close to the additive molecule suggest that (3) modification of the solvent by the additive molecule contributes to viscosity enhancement.

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Acknowledgements

We thank David Gray, Joan Souchik and Paul Michael for useful discussion and feedback related to viscosity modifiers. We also acknowledge the Donors of the American Chemical Society Petroleum Research Fund (Grant #55026-ND6), National Science Foundation Engineering Research Center for Compact and Efficient Fluid Power EEC 05440834, and the National Fluid Power Association Education and Technology Foundations Pascal Society for support of this research.

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Authors and Affiliations

  1. Department of Mechanical Engineering, University of California Merced, Merced, CA, USA

    Michelle Len, Uma Shantini Ramasamy & Ashlie Martini

  2. Department of Mechanical Engineering, Northwestern University, Evanston, IL, USA

    Seth Lichter

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  1. Michelle Len
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  2. Uma Shantini Ramasamy
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  3. Seth Lichter
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  4. Ashlie Martini
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Correspondence to Ashlie Martini.

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Len, M., Ramasamy, U.S., Lichter, S. et al. Thickening Mechanisms of Polyisobutylene in Polyalphaolefin. Tribol Lett 66, 5 (2018). https://doi.org/10.1007/s11249-017-0960-3

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  • DOI: https://doi.org/10.1007/s11249-017-0960-3

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