One of the potential applications of the ionic liquids (ILs) is their use as lubricants or lubricant additives. The choice of the cation and the anion of the ILs, as well as the side chain design, determine their fundamental properties, which permits us to create tailor-made lubricants and lubricant additives among other functional fluids. In this work we have studied 10 ILs for which we report densities and viscosities from 283.15 K (and for some ILs at lower temperatures) up to 373.15 K. The viscosities of the ILs fall in the range of the applications of hydraulic fluid or lubricants. Four of these ILs were composed by the anion tris(pentafluoroethyl)trifluorophosphate [(C 2 F 5 ) 3 PF 3 ] À and one of the following cations:and trihexyl(tetradecyl)phosphonium [P 6,6,6,14 ] + . Furthermore, three of the ILs contain the anion bis(trifloromethylsulfonyl)imide [NTf 2 ] À and one of the following cations [C 4 C 1 C 1 mim] + , [C 4 C 1 Pyrr] + , or [C 1 OC 2 C 1 Pyrr] + . Two other ILs contain the 1-ethyl-3-methylimidazolium cation [C 2 C 1 mim] + and an alkyl sulfate anion (ethylsulfate [C 2 SO 4 ] À or n-hexylsulfate [C 6 SO 4 ] À ). The last one is composed by [C 4 C 1 Pyrr] + and trifluoromethanesulfonate [CF 3 SO 3 ] À . The experimental values were used to determine the glass-transition temperature and fragility of these ILs and to analyze the capability of two group contribution methods recently proposed by Gardas and Coutinho for the density and viscosity prediction of ILs.

This paper presents new reference correlations for both the density and viscosity of squalane at high pressure. These correlations are based on critically evaluated experimental data taken from the literature. In the case of the density, the correlation, based on the Tait equation, is valid from 273 to 473 K at pressures to 200 MPa. At 0.1 MPa, it has an average absolute deviation of 0.03%, a bias of −0.01%, and an expanded uncertainty (at the 95% confidence level) of 0.06%. Over the whole range of pressures, the density correlation has an average absolute deviation of 0.05%, a bias of −0.004%, and an expanded uncertainty (at the 95% confidence level) of 0.18%. In the case of the viscosity, two correlations are presented, one a function of density and temperature, based on the Assael-Dymond model, and the other a function of temperature and pressure, based on a modified Vogel-Fulcher-Tammann equation. The former is slightly superior to the latter at high temperatures (above 410 K), whereas the reverse is true at low temperatures, where the viscosity is strongly temperature dependent. In the temperature range from 320 to 473 K at pressures to 200 MPa, the first correlation has an average absolute deviation of 1.41%, a bias of −0.09%, and an expanded uncertainty (at the 95% confidence level) of 3%. Below 320 K, deviations from the present scheme rise to a maximum of 20%. In the temperature range from 278 to 473 K at pressures to 200 MPa, the second viscosity correlation has an average absolute deviation of 1.7%, a bias of −0.04%, and an expanded uncertainty (at the 95% confidence level) of 4.75%.

International audienceThe paper presents a new reference correlation for the viscosity of squalane at 0.1 MPa. The correlation should be valuable as it is the first to cover a moderately high viscosity range, from 3 to 118 mPa s. It is based on new viscosity measurements carried out for this work, as well as other critically evaluated experimental viscosity data from the literature. The correlation is valid from 273 to 373 K at 0.1 MPa. The average absolute percentage deviation of the fit is 0.67, and the expanded uncertainty, with a coverage factor k = 2, is 1.5%

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