Investigation of shear-Thinning behavior on film thickness and friction coefficient of polyalphaolefin base fluids with varying olefin copolymer content

J. Zolper Thomas, Yifeng He, Massimiliano Delferro, Paul Shiller, Gary Doll, Babak Lotfizadeh Dehkordi, Ning Ren, Frances Lockwood, Tobin J Marks, Yip Wah Chung, Aaron Greco

Research output: Contribution to journalArticle

3 Citations (Scopus)


This study investigates the rheological properties, elastohydrodynamic (EHD) filmforming capability, and friction coefficients of low molecular mass poly-A-olefin (PAO) base stocks with varying contents of high molecular mass olefin copolymers (OCPs) to assess their shear stability and their potential for energy-efficient lubrication. Several PAO-OCP mixtures were blended in order to examine the relationship between their additive content and tribological performance. Gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy were used to characterize the molecular masses and structures, respectively. Density, viscosity, EHD film thickness, and friction were measured at 303 K, 348 K, and 398 K. Film thickness and friction were studied at entrainment speeds relevant to the boundary, mixed, and full-film lubrication regimes. The PAO-OCP mixtures underwent temporary shear-Thinning resulting in decreases in film thickness and hydrodynamic friction. These results demonstrate that the shear characteristics of PAO-OCP mixtures can be tuned with the OCP content and provide insight into the effects of additives on EHD characteristics.

Original languageEnglish
Article number021504
JournalJournal of Tribology
Issue number2
Publication statusPublished - Apr 1 2017



  • elastohydrodynamic lubrication
  • fluid friction (traction)
  • lubricant additives
  • viscosity

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

Cite this