Relative permittivity of organic liquids as a function of pressure and temperature

Scaife, W Garrett

doi:10.1088/0305-4470/4/3/019

Cited by 19 publications

(12 citation statements)

References 22 publications

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13] Work at the time was hampered by the long and tedious manual procedures required to make dielectric measurements for different pressures at different temperatures. More recently, however automated data collection techniques as well as the data analysing techniques 14,15 have made such studies more revealing of the effects observed at pressures especially exceeding 500 MPa (5 kbar).…”

Section: Introductionmentioning

confidence: 99%

Effect of high hydrostatic pressure on the dielectric relaxation in a non-crystallizable monohydroxy alcohol in its supercooled liquid and glassy states

Pawlus

Paluch

Nagaraj

et al. 2011

The Journal of Chemical Physics

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The complex relative permittivity of a non-crystallizable secondary alcohol, 5-methyl-2-hexanol, is measured over a wide range of temperatures and pressures up to 1750 MPa (17.5 kbar). The data at atmospheric pressure (P = 0.101 MPa) are analyzed in terms of three processes, and the results are in complete agreement with that of O. E. Kalinovskaya and J. K. Vij [J. Chem. Phys. 112, 3262 (2000)]. Process I is of the Debye type and process II is of the Davidson-Cole type, whereas process III is identified as the Johari-Goldstein relaxation process. For pressures of ∼500 MPa and higher, processes I and II are seen to merge into each other to form a single dominant process which unambiguously cannot be resolved into more than one process. The dielectric relaxation strength of process I decreases slightly initially with pressure and when the two processes have merged at elevated pressures, the total relaxation strength increases with increase in pressure. Process III is better resolvable at higher pressures especially above T g in the supercooled liquid state for the reason that the separation in the time scales between the dominant and the JG relaxation process increases at elevated pressures. Surprisingly we find a change in the slope in the plot of log τ JG vs. 1/T for P = 1750 MPa. The results for the relaxation time of alcohols are compared with the Kirkwood correlation factor, g, and it is found that higher is the g, lower is the relaxation time for process I, and it is more of the Debye type. On a reduction in g brought about by an increase in pressure at lower temperatures, the dominant process becomes non-Debye though extensive hydrogen bonding is still present. The dielectric strength of the merged processes increases with increase in pressure. The values of the steepness index, m = |d log τ /d(T g /T)| T = Tg for processes I and II are different for P = 0.1 MPa. However the value of m, for the composite process, which is a merger of processes I and II, for P = 1750 MPa is almost the same for process II at P = 0.1 MPa. From the results of the activation volume, activation enthalpy, and a comparison of the relaxation times with the g factor, we conclude that both processes I and II are significantly affected by hydrogen bonding and both contribute to the structural relaxation.

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Section: Introductionmentioning

confidence: 99%

Effect of high hydrostatic pressure on the dielectric relaxation in a non-crystallizable monohydroxy alcohol in its supercooled liquid and glassy states

Pawlus

Paluch

Nagaraj

et al. 2011

The Journal of Chemical Physics

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“…The ε r ( p = 0.1 MPa) reported by other workers ,,− are shown as deviations from eq in Figure . The ε r ( p = 0.1 MPa) of Smyth and Snoops that were obtained with a concentric cylinder capacitor all lie within the estimated uncertainty of eq in the overlapping temperature range, and also at temperatures down to 183.15 K, an extrapolation of 120 K below the lowest temperature of our measurements; only values to a temperature of 253.15 K are shown in Figure .…”

Section: Resultsmentioning

confidence: 86%

“…Fractional deviations Δε r = ε r (expt) – ε r (calc) of the measured relative electric permittivity ε r (expt) of heptane as deviations from the calculated values ε r (calc) of eq at p = 0.1 MPa. ●, This work, Table ; ◇, ref ; +, ref ; □, ref ; ○, ref ; ×, ref ; △, ref . The dashed lines at 0 indicate an extrapolation of eq , while the solid line indicates the temperature range of the fit to eq .…”

Section: Resultsmentioning

confidence: 99%

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Determination of the Relative Permittivity, ε_r, of Heptane at Temperatures between (303 and 363) K and Pressures below 60 MPa with a Concentric Cylinder Capacitor at a Frequency of 1 kHz

et al. 2013

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The relative electric permittivity, ε r (T, p), of liquid heptane has been determined with an estimated relative expanded uncertainty of ± 0.018 % from measurements of the complex capacitance of a concentric cylinder capacitor at temperatures between (293 and 363) K and pressures below 60.6 MPa. The measurements were corrected for the capacitor's isothermal compressibility that was determined by comparison of measurements of ε r (He, 303 K and 393 K, p) with ab initio results from quantum mechanics. The measured ε r (C 7 H 16 , T, p) were combined with the amount-of-substance density, ρ, which was obtained from the equation of state reported by Span and Wagner (Int. J. Thermophys. 2003, 24, 41−109), to calculate the total molar polarizability, P, that was fit with an expanded (k = 2) relative uncertainty of ± 0.06 % to a correlation with three parameters. The ε r (T, p) obtained from the literature were converted to P•ρ, compared with our correlation, and found to have a relative difference of < ± 0.5 % at temperatures that overlap ours.

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“… a From ref . Hereinafter, ε 1 means the value of relative permittivity at ambient pressure (1 bar). b From ref . c From ref . d From ref . …”

Section: Resultsmentioning

confidence: 99%

Changes in Permittivity and Density of Molecular Liquids under High Pressure

2014

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We collected and analyzed the density and permittivity of 57 nonpolar and dipolar molecular liquids at different temperatures (143 sets) and pressures (555 sets). No equation was found that could accurately predict the change to polar liquid permittivity by the change of its density in the range of the pressures and temperatures tested. Consequently, the influence of high hydrostatic pressure and temperature on liquid permittivity may be a more complicated process compared to density changes. The pressure and temperature coefficients of permittivity can be drastically larger than the pressure and temperature coefficients of density, indicating that pressure and particularly temperature significantly affect the structure of molecular liquids. These changes have less influence on the density change but can strongly affect the permittivity change. The clear relationship between the tangent and secant moduli of the permittivity curvatures under pressure for various molecular liquids at different temperatures was obtained, from which one can calculate the Tait equation coefficients from the experimental values of the pressure influence on the permittivity at ambient pressure.

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Relative permittivity of organic liquids as a function of pressure and temperature

Cited by 19 publications

References 22 publications

Effect of high hydrostatic pressure on the dielectric relaxation in a non-crystallizable monohydroxy alcohol in its supercooled liquid and glassy states

Effect of high hydrostatic pressure on the dielectric relaxation in a non-crystallizable monohydroxy alcohol in its supercooled liquid and glassy states

Determination of the Relative Permittivity, ε_r, of Heptane at Temperatures between (303 and 363) K and Pressures below 60 MPa with a Concentric Cylinder Capacitor at a Frequency of 1 kHz

Changes in Permittivity and Density of Molecular Liquids under High Pressure

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Relative permittivity of organic liquids as a function of pressure and temperature

Cited by 19 publications

References 22 publications

Effect of high hydrostatic pressure on the dielectric relaxation in a non-crystallizable monohydroxy alcohol in its supercooled liquid and glassy states

Effect of high hydrostatic pressure on the dielectric relaxation in a non-crystallizable monohydroxy alcohol in its supercooled liquid and glassy states

Determination of the Relative Permittivity, εr, of Heptane at Temperatures between (303 and 363) K and Pressures below 60 MPa with a Concentric Cylinder Capacitor at a Frequency of 1 kHz

Changes in Permittivity and Density of Molecular Liquids under High Pressure

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Determination of the Relative Permittivity, ε_r, of Heptane at Temperatures between (303 and 363) K and Pressures below 60 MPa with a Concentric Cylinder Capacitor at a Frequency of 1 kHz