Temperature and Pressure Dependence of the Viscosities of Krytox GPL102 Oil and Di(pentaerythritol) Hexa(isononanoate)

Abstract

This work reports high-pressure viscosity measurements on two viscous liquids that may prove useful as high-temperature, high-viscosity reference materials, Krytox GPL102 and di(pentaerythritol) hexa-(isononanoate). The perfluoropolyether oil, Krytox GPL102, is the subject of a round-robin comparison of high-pressure viscosity measurements on a specific sample being made by a group of laboratories worldwide employing a variety of viscometric techniques. Viscosity data are reported between (0 and 95) °C, at pressures to 226 MPa and viscosities between (6 and 4182) mPa•s. For the more viscous di(pentaerythritol) hexa(isononanoate), data are reported between (0 and 90) °C, at pressures to 203 MPa and viscosities between (34 and 2269) mPa•s. Correlations are provided using modified Vogel−Fulcher−Tammann (VFT) equations for both substances, a modified Litovitz equation for Krytox GPL102 and a modified Barlow-Lamb equation for di(pentaerythritol) hexa(isononanoate). Glass temperatures are estimated to be (178.2 and 218.1) K, respectively, based on the Angell equation relating the VFT parameters to T g . Thermodynamic scaling is applied to both the experimental and reduced viscosities. The scaling parameters found are consistent with previous work on chain molecular compounds and esters.

Temperature and Pressure Dependence of the Viscosity of the Ionic Liquid 1-Butyl-3-methylimidazolium Acetate

“…The atmospheric pressure data were fitted to the Vogel–Fulcher–Tammann (VFT) equation, the Litovitz equation being unsuitable in this case The high-pressure data were fitted to a modified form used in previous viscosity studies (MVFT1) ,− , The fitted coefficients for the various samples are given in Tables and , respectively. There appear to be no high-pressure data in the literature available for comparison.…”

“…It is now generally agreed that it is the reduced forms of the transport properties that should be scaled using dimensionless expressions suggested by kinetic theory, with scaling being made in terms of the mean interparticle distance, d = v 1/3 [where v is the molecular volume ( V / N A ), V being the molar volume], and the thermal velocity, u th = ( k B T / m ) [where m is the molecular mass ( M / N A ), M being the molar mass] . For the viscosity, the appropriate expression is Table shows the values of γ for [BMIM]­[Ac] and a number of other [BMIM] + salts. ,, Figure shows the scaled fit. While the values of γ are similar, the fit for [BMIM]­[Ac] is slightly poorer (Figure ), showing some systematic deviations.…”

“…The techniques used for high-pressure falling body viscometry have been fully described in earlier studies. ,− The unit was calibrated with Cannon Instrument Co. standard viscometer oils: 5.9 mm sinkerS20, N100, N350, and S2000, 293.15–363.15 K, 15.3–4285 mPa·s; 6.0 mm sinkerN100 and S2000, 293.15–363.15 K, 16–2253 mPa·s. The calibration constants are independent of temperature.…”

In Pursuit of a High-Temperature, High-Pressure, High-Viscosity Standard: The Case of Tris(2-ethylhexyl) Trimellitate

“…RT M (11) and substitution of typical values for TOTM yields, for the Newtonian limit, a shear stress of approximately 5 MPa. The viscosities measured by Bair are listed in Table 7.…”

“…At the time the project was conceived, there were no available fluids satisfying these conditions as well as all those features normally expected of a standard reference material such as low toxicity, ready availability, and uniformity from lot-to-lot from a manufacturer. During the overall IATP project to date, a number of reference fluids have been proposed and examined including DIDP, − Squalane, − and Krytox. − In turn, each of these proposals has moved the project nearer to fulfillment of its objective. In this work, we report on the latest development with regard to the examination of the liquid 1,2,4-benzenetricarboxylic acid tris­(2-ethylhexyl) ester (CAS-No.…”