Thermal conductivities are reported for a series of 1-alkyl-3-methylimidazolium hexafluorophosphates having butyl, hexyl, and octyl groups, which are expressed by [bmim][PF 6 ], [hmim][PF 6 ], and [omim] [PF 6 ], respectively. The experimental method used was a transient short-hot-wire method. Since only a small amount of sample liquid is required, this method was found to be effective for the thermal-conductivity measurements of ionic liquids (ILs). The experimental temperatures ranged from 294 to 335 K at pressures up to 20 MPa. The values of the thermal conductivities of ILs at normal pressure are similar to those of benzene. It was found that an effect of the length of the alkyl chain on the thermal conductivities in ILs is negligible. From the data for the thermal conductivity and viscosity at 293.15 K and 0.1 MPa of ILs and normal alkanes, a simple correlation was developed based on the Mohanty theory. From comparisons between the thermal conductivities of ILs and those of organic liquids (n-hexane, benzene, and methanol), the temperature and pressure dependences of the thermal conductivity of ILs are relatively weak.

The viscosities of 1-hexyl-3-methylimidazolium hexafluorophosphate ([hmim][PF 6 ]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([omim][PF 6 ]) were measured with a rolling ball viscometer. The experimental temperatures were from (293.15 to 353.15) K and pressures were up to 20.0 MPa. The experimental values were correlated with a Vogel-Tamman-Fulcher (VTF) equation and a Tait-form equation.

Viscosity and thermal conductivity values are reported for a series of 1-alkyl-3-methylimidazolium tetrafluoroborate compounds with hexyl (1-hexyl-3-methylimidazolium tetrafluoroborate) and octyl (1-octyl-3-methylimidazolium tetrafluoroborate) groups. The viscosity was measured with a rolling-ball viscometer at 293.15 K to 353.15 K and pressures up to 20.0 MPa. The experimental values were correlated with a hybrid VFT-Tait equation. The thermal conductivity was measured using the transient short hot-wire method at 294 K to 335 K and pressures up to 20.0 MPa. The experimental values at 293.15 K and 0.1 MPa agreed with the predicted values proposed by Fröba et al.

Ionic liquids are salts that are liquid at room temperature. They have attracted considerable attention as new materials. In this study, a transient short-hot-wire apparatus was prepared, and the thermal conductivity of 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim] [BF 4 ]) was measured. The experimental temperatures were from 294 to 334 K, and the pressures were from 0.1 to 20 MPa. It was found that the thermal conductivity of an ionic liquid has a very small temperature and pressure dependence.

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