Temperature and Pressure Dependence of the Viscosities of 2-Ethylhexyl Benzoate, Bis(2-ethylhexyl) Phthalate, 2,6,10,15,19,23-Hexamethyltetracosane (Squalane), and Diisodecyl Phthalate

The viscosities of the esters 2-ethylhexyl benzoate (EHB), bis(2-ethylhexyl) phthalate (DEHP), and the long-chain hydrocarbon 2,6,10,15,19,23-hexamethyltetracosane (squalane, C 30 H 62 ) have been measured between (0 and 80) °C with a falling-body viscometer to a maximum pressures of (315, 371, and 379) MPa, respectively. The expanded uncertainty is estimated at ± 2 %. These substances are possible alternatives to diisodecyl phthalate (DIDP) as reference materials for viscometry at moderate to high pressures. In addition, further measurements for DIDP are reported in the range (0.1 to 90) MPa and (25 to 75) °C to supplement those given by Harris and Bair ( J. Chem. Eng. Data, 2007, 52, 272−278). These are compared with vibrating-wire measurements reported by Al Motari et al. ( J. Chem. Eng. Data, 2007, 52, 1233−1239). The data have also been fitted as a function of the quantity ( TV γ ) using the thermodynamic scaling method of Roland et al. ( J. Chem. Phys. 2006, 125, 124508-1−124508-8), yielding scaling parameters, γ, equal to 3.69, 3.65, 4.16, and 3.96 for EHB, DEHP, squalane, and DIDP, respectively.