Pressure–Viscosity Coefficients for Polyalkylene Glycol Oils and Other Ester or Ionic Lubricants

Abstract

We present in this article new viscosity and density data for polypropylene glycol monomethyl ether, which completes a series of articles where we have published dynamic viscosity data of poly(propylene glycol) dimethyl ethers, dipentaerythritol esters, and pentaerythritol esters. New dynamic viscosity measurements up to 60 MPa at five temperatures in the range of 303.15–373.15 K, and density values at temperatures ranging from 298.15 to 398.15 K up to 60 MPa are reported in addition to other physical properties that affect the behavior of the fluids in elastohydrodynamic lubrication regime, such as the viscosity index value, VI, the universal pressure–viscosity coefficient, α film, and the temperature–viscosity coefficient, β. The experimental measurements were performed using a rotational automated viscometer Anton Paar Stabinger SVM3000, a rolling-ball viscometer Ruska 1602-830 for high pressures, and an automated Anton Paar DMA HPM vibrating-tube densimeter. Together with these data, we also present a comparison of the film-generating capability for the fluids above mentioned as well as for other five ionic liquids. We analyze the dependence of the molecular structure on the lubrication properties of these oils, which can help the lubricant engineers to develop products with enhanced performance.