Thermophysical Properties of Binary Mixtures of Methanol with Chlorobenzene and Bromobenzene from 293 K to 313 K

Densities and viscosities have been measured for the binary mixtures of methanol with chlorobenzene and with bromobenzene from 293 K to 313 K over the complete composition range. Densities were used to compute the excess molar volume ( , for these binary systems. The results have been discussed in terms of molecular interactions. Furthermore, viscosity results were compared with a corresponding-states model. The average absolute deviation was found to be 1.9 %.     

Densities and Volumetric Properties of Binary Mixtures of Butyl Acrylate with Benzene, Toluene, o-Xylene, m-Xylene, p-Xylene, and Mesitylene at Temperatures from 288.15?K to 318.15?K

The densities, ρ, of binary mixtures of butyl acrylate (BA) with benzene, toluene, o-xylene, m-xylene, p-xylene, and mesitylene, including those of pure liquids, over the entire composition range were measured at the temperatures (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 318.15) K and atmospheric pressure. From the experimental data, the excess molar volumes, V_m^E{V_{\rm m}^{\rm E}} were calculated. The V_m^E{V_{\rm m}^{\rm E}} values were negative over the whole composition range for all the mixtures and at each temperature studied, except for BA + mesitylene which exhibit positive V_m^E{V_{\rm m}^{\rm E}} values, indicating the presence of specific interactions between BA and aromatic hydrocarbon molecules. The deviations in V_m^E{V_{\rm m}^{\rm E}} values follow the order: benzene<toluene<p-xylene<m-xylene<o-xylene<mesitylene. It is observed that V_m^E{V_{\rm m}^{\rm E}} values depend upon the number and position of the methyl groups in these aromatic hydrocarbons.     

Densities and Volumetric Properties of Binary Mixtures of Aniline with 1-Propanol, 2-Propanol, 2-Methyl-1-Propanol,and 2-Methyl-2-Propanol at Temperatures from 293.15 to 318.15 K

The densities of binary mixtures of aniline with 1-propanol, 2-propanol, 2-methyl-1-propanol, and 2-methyl-2-propanol were measured over the entire composition range, along with the pure components, at temperatures of 293.15, 298.15, 303.15, 308.15, 313.15, and 318.15 K and atmospheric pressure. Using the experimental data, the excess molar volumes, , and the temperature coefficients of the excess molar volume, for the binary mixtures were calculated. The variations of these parameters with composition and temperature of the mixtures have been discussed in terms of molecular interactions in these mixtures. The values were found negative for all the mixtures at each temperature studied, indicating the presence of specific interactions between aniline and alkanol molecules. The extent of negative deviations in values follows the order: 1-propanol < 2-propanol < 2-methyl-1-propanol < 2-methyl-2-propanol. It is observed that the values depend upon the positions of hydroxyl and methyl groups in these alkanol molecules.     

Thermal Conductivity of Carbon Dioxide–Methane Mixtures at Temperatures Between 300 and 425 K and at Pressures up to 12 MPa

The thermal conductivities of carbon dioxide and three mixtures of carbon dioxide and methane at six nominal temperatures between 300 and 425 K have been measured as a function of pressure up to 12 MPa. The measurements were made with a transient hot-wire apparatus. The relative uncertainty of the reported thermal conductivities at a 95% confidence level is estimated to be ±1.2%. Results of the low-density analysis of the obtained data were used to test expressions for predicting the thermal conductivity of nonpolar mixtures in a dilute-gas limit developed by Schreiber, Vesovic, and Wakeham. The scheme was found to underestimate the experimental thermal conductivity with deviations not exceeding 5%. The dependence of the thermal conductivity on density was used to test the predictive scheme for the thermal conductivity of gas mixtures under pressure suggested by Mason et al. and improved by Vesovic and Wakeham. Comparisons reveal a pronounced critical enhancement on isotherms at 300 and 325 K for mixtures with methane mole fractions of 0.25 and 0.50. For other states, comparisons of the experimental and predicted excess thermal conductivity contributions showed a smaller increase of the experimental data with deviations approaching 3% within the examined range of densities.     

Viscosities for Binary Mixtures of 1-Bromobutane and 1,4-Dibromobutane with Isomeric Butanols at 298.15 and 313.15 K

This paper reports viscosities and viscosity deviations for binary mixtures of 1-bromobutane and 1,4-dibromobutane with an isomer of butanol at temperatures of 298.15 and 313.15K. Absolute viscosities were correlated using the Grunberg–Nissan equation, and kinematic viscosities by the equations of McAllister and Heric. Viscosity deviations were correlated by means of a Redlich–Kister-type equation. Viscosity deviations show negative values at both temperatures over the complete composition range.     

Isochoric Heat Capacities of Propane + Isobutane Mixtures at Temperatures from 280 to 420 K and at Pressures to 30 MPa

The isochoric heat capacity (c_v) and pressure–volume–temperature-composition (pvTx) properties were measured for propane + isobutane mixtures in the liquid phase and in the supercritical region. The expanded uncertainty (k = 2) of temperature measurements is estimated to be ±13 mK, and that of pressure measurements is ±8 kPa. The expanded relative uncertainty for c_v is ±3.2% for the liquid phase, increasing to ±4.8% for near-critical densities. The expanded uncertainty for density is estimated to be ±0.16%. The present measurements for {xC₃H₈ +(1−x)i-C₄H₁₀} with x = 0.0, 0.498, 0.756, and 1.0, were obtained at 659 state points at temperatures from 270 to 420 K and at pressures up to 30 MPa. The experimental data were compared with a published equation of state. Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A.     

Topological Investigations of Excess Molar Volumes and Excess Isentropic Compressibilities of Ternary Mixtures Containing Pyrrolidin-2-one at 308.15 K

Excess molar volumes, ${V^{\rm E}_{ijk}}$ , and speeds of sound, u _ijk , of pyrrolidin-2-one (2-Py) (i)+benzene or methyl benzene (j)+propan-1-ol (k) ternary mixtures and speeds of sound, u _ij , of benzene or methyl benzene (i)+propan-1-ol (j) binary mixtures have been measured dilatometrically and interferrometrically over the complete mole fraction range at 308.15 K. Speed-of-sound data have been utilized to evaluate excess isentropic compressibilities for binary and ternary mixtures. ${V^{\rm E}_{ijk}}$ and ${\left({\kappa_S^{\rm E}}\right)_{ijk}}$ values have been fitted to a Redlich–Kister equation to predict ternary adjustable parameters and standard deviations. Topological investigations employed for predicting excess molar volumes and excess isentropic compressibilities, ${\left({\kappa _S^{\rm E}} \right)_{ij}}$ , of 2-Py + benzene or methyl benzene or propan-1-ol binary mixtures have been extended to ternary mixtures (by employing the concept of a connectivity parameter of third degree, ³ ξ, of a molecule) to obtain an expression that describes well the measured ${V^{\rm E}_{ijk}}$ and ${\left({\kappa_S^{\rm E}}\right)_{ijk}}$ values.     

Measurements of the Properties of Binary Mixtures of Dimethylsulphoxide (DMSO) with 1-Alkanols (C4, C6, C7) at 303.15 K

This paper presents experimental data for densities, ρ, ultrasonic velocities, u, and refractive indices, n, of pure dimethylsulphoxide (DMSO), 1-butanol, 1-hexanol, 1-heptanol, and their binary mixtures, with DMSO as a common component, over the whole composition range at 303.15 K. The molar refraction, R_m, molecular association, M_A, excess molar volume, V^E, and deviation in isentropic compressibility, ΔK_s, were calculated from the experimental data. The apparent molar volume, V_ϕ,2, and apparent molar isentropic compressibility, K_ϕ,2, of alkanols in DMSO were also calculated. The values of V_ϕ,2 and K_ϕ,2 were used to estimate the partial molar volume, , and partial molar isentropic compressibility, , of alkanols in DMSO at infinite dilution. The changes in these parameters with composition and the size of the alkyl chain length in the alkanol molecule are discussed with reference to the nature of interactions between component molecules. Excess molar volumes have also been estimated from measurements of refractive indices     

Thermodynamic Properties of Liquid 3He-4He Mixtures Between 0–10 bar below 1.5 K

The thermodynamic properties of liquid ³He-⁴He mixtures at pressures of up to 10 bar and temperatures below 1.5 K are determined. The calculations are based on previously determined thermodynamic properties of ³He-⁴He mixtures at saturated (zero) pressure, and available experimental measurements of the molar volume, which are used to determine an expression for the molar volume. Since available experimental data for mixtures at higher pressures are restricted to low temperatures (below about 0.7 K), the calculated molar volumes at high pressure and high temperature are largely based on pure ³He and pure ⁴He data.     

Speed of Sound in Pure Water at Temperatures between 274 and 394 K and at Pressures up to 90 MPa

A newly designed experimental apparatus has been used to measure the speed of sound u in high-purity water on nine isotherms between 274 and 394 K and at pressures up to 90 MPa. The measurement technique is based on a traditional double-reflector pulse-echo method with a single piezoceramic transducer placed at unequal distances from two stainless steel reflectors. The transit times of an acoustic pulse are measured at a high sampling rate by a digital oscilloscope. The distances between the transducer and the reflectors were obtained at ambient temperature and pressure by direct measurements with a coordinate measuring machine. The speeds of sound are subject to an overall estimated uncertainty of 0.05 %. The acoustic data were combined with available values of density ρ and isobaric heat capacity c_p along one isobar at atmospheric pressure to calculate the same quantities over the whole temperature and pressure range by means of a numerical integration technique. These results were compared with those calculated from the IAPWS-95 formulation with corresponding relative deviations which are within 0.1%. Paper presented at the Fifteenth Symposium on Thermophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A.     

Realization of a 3He�C4He Vapor-Pressure Thermometer for Temperatures Between 0.65?K and 5?K at LNE-CNAM

In the temperature range between 0.65 K and 5 K, the International Temperature Scale of 1990 (ITS-90) is based on ³He and ⁴He vapor-pressure thermometers. Between 0.65 K and 1 K, the ITS-90 overlaps with the Provisional Low Temperature Scale of 2000 (PLTS-2000), defined in term of the melting pressure of ³He. Some differences, up to more than 1 mK, exist between the two scales in the overlapping interval. The LNE-CNAM has recently started the construction of a ³He?C⁴He vapor-pressure thermometer to realize the ITS-90 in its lowest subrange at the highest degree of accuracy. The device is provided with two separate vapor-pressure chambers, one for ³He and the other for ⁴He, built in a single copper block, and is installed in the experimental space of a dilution refrigerator. The vapor-pressure thermometer is designed to accommodate on the same copper block several transfer standards, an acoustic thermometer, and the ³He melting-pressure thermometer. This configuration is intended for realizing calibrations of transfer standards down to 0.65 K, for investigating the possibility to extend the acoustic thermometer below 4 K, and to perform a direct comparison between the ITS-90 and the PLTS-2000 in the overlapping temperature range, in order to study their differences. The realization of the system has been recently accomplished, and this report illustrates the characteristics of such an experimental device.     

Thermal and Electrical Properties of Titanium Between 300 and 1900 K

The specific heat capacity and electrical resistivity of titanium were measured by a subsecond pulse-heating method. Specimens were in the form of a 1.6-mm-diameter-wire. Experiments covered the range between 300 and 1900K; thermometry was provided by Pt10%Rh/Pt and W5%Re/W25%Re thermocouples. The maximum uncertainties in the specific heat capacity and electrical resistivity determinations were less than 3 and 1%, respectively. Results are reported and discussed for both the bcc and hcp structures and the transformation between the two phases.     

Volumetric Properties of Binary Mixtures of 2,4,6-Trimethylpyridine with 1,2-Ethanediol,Methanol, and Water,and the Association Energies of the O–H· · ·N Bonded Complexes

2,4,6-Trimethylpyridine forms 1:1 complexes with methanol, 1,2-ethanediol, and water due to the O–H· · ·N bonds. The association energy of the complexes was calculated using MP2 and DFT methods. The complexes with 1,2-ethanediol and water aggregate in the liquid phase as a result of the O–H· · ·O bonds. In spite of the higher O–H· · ·N bond energy, the aggregation of the ethanediolic complexes is less pronounced than that of the aqueous ones. That is probably caused by the weaker induction effect due to the C–C chain separating the hydroxyl groups in the diol molecule. Aggregation is impossible in the methanolic system, because of the lack of proton-donating functional groups. Differences in the hydrogen bond energy and in the ability to aggregate are manifested in the volumetric properties of the mixtures.     

Densities,Viscosities, and Refractive Indices of Binary Mixtures of Benzene with Isomeric Butanols at 30°C

The densities, , viscosities, , and refractive indices, n, of binary mixtures of benzene with 1-butanol, 2-methyl-1-propanol, 2-butanol, and 2-methyl-2-propanol, including those of the pure liquids, were measured over the complete composition range at 30°C. The dependence of , , and n on composition was checked by using an empirical relation. The experimental data were used to calculate excess molar volumes, V^E, deviations in viscosity, , excess free energies of activation of viscous flow, G^*E, deviations in refractive index, n, apparent molar volumes, V_,1 and V_{, 2}, and partial molar volumes, , of benzene in alcohols and alcohols in benzene, respectively, at infinite dilution. The variations of these parameters with composition and the effect of branching in alcohols were discussed from the point of view of intermolecular interactions in these mixtures.     

Measurement of the (p, \rho,T) Properties for Pure Hydrocarbons at Temperatures up to 600 K and Pressures up to 200 MPa

The data available for the thermodynamic properties of propane, \(n\) -butane, and isobutane at temperatures above 440 K are outdated and show significant discrepancies with each other. The ambiguity associated with these data could be limiting to the development of any understanding related to the effects of mixing of these substances with other materials such as \(\text{ CO}_{2}\) , ammonia, and non-flammable or lower-flammable HFC refrigerants. In this study, the (p, \(\rho \) , T) properties of propane, \(n\) -butane, and isobutane were measured at temperatures ranging from (360 to 600) K and pressures ranging from (50 to 200) MPa. Precise measurements were carried out using a metal-bellows variable volumometer with a thermostatted air bath. The expanded uncertainties \((k = 2)\) in the temperature, pressure, and density measurements were estimated to be \(<\) 5 mK, 0.02 MPa, and 0.88 kg  \(\cdot \)  m \(^{-3}\) ( \(T\le 423\)  K, \(p<100\)  MPa), 0.76 kg  \(\cdot \)   \(\text{ m}^{-3}\) ( \(T\le 423\)  K, \(p\ge 100\)  MPa), 0.76 kg  \(\cdot \)   \(\text{ m}^{-3}\) ( \(T>423\)  K, \(p < 100\)  MPa), and 2.94 kg  \(\cdot \)   \(\text{ m}^{-3}\) ( \(T>423\)  K, \(p \ge 100\)  MPa), respectively. The data obtained throughout this study were systematically compared with the calculated values derived from the available equations of state. These models agree well with the measured data at higher temperatures up to 600 K, demonstrating their suitability for an effective and precise examination of the mixing effects of potential alternative mixtures.     

pρT Measurements of Polyethylene Glycol Dimethylethers Between 278.15 and 328.15 K at Pressures to 12 MPa

In this paper we present a new experimental apparatus designed to measure pressure–density–temperature (pT ) properties with a high-pressure vibrating tube densimeter. Data reliability has been verified by comparing our experimental results for methanol, n-heptane, toluene, and HFC-134a with literature data. In this work we also report new experimental densities from 278.15 to 328.15 K, and up to 12 MPa, of triethylene glycol dimethylether (TrEGDME) and tetraethylene glycol dimethylether (TEGDME). The isobaric thermal expansion coefficients, isothermal compressibility, and internal pressure have been calculated. The dependence of these properties on the length of polyethylene glycol dimethylether, CH₃O–((CH₂)₂O) _n –CH₃, is analyzed.     

Characteristics of Standard Capsule-Type PtCo Resistance Thermometers Between 0.65 K and 25 K

Standard capsule-type platinum–cobalt (PtCo) resistance thermometers represent one of the few types of resistance thermometers that have been developed for precise thermometry in the cryogenic temperature range. These thermometers remain sensitive even at 0.65 K, which is the lower limit of the ITS-90. Standard capsule-type rhodium–iron (RhFe) resistance thermometers are another type of resistance thermometer intended for use in this temperature range and have been well characterized and are the de facto standard worldwide. Existing data show RhFe resistance thermometers are more reproducible than the corresponding PtCo resistance thermometer. However, it has become difficult to obtain brand-new standard capsule-type RhFe resistance thermometers since their production was discontinued in the early 2000s. Unfortunately, information regarding the characteristics of standard capsule-type PtCo resistance thermometers is limited compared to that available for RhFe resistance thermometers. In this study, the characteristics of two standard capsule-type PtCo resistance thermometers between 0.65 K and 25 K were investigated. Because the resistance versus temperature curves for these thermometers over this temperature range exhibit two inflection points, setting break points near each of the inflection points was found to be beneficial during polynomial curve fitting to obtain mK-level precision. Special attention was paid to the reproducibility of these thermometers, and it was observed that the reproducibility of one of the thermometers within the cryogenic temperature range was ±0.5 mK over 6 years, while the second thermometer showed a larger variation. Similar trends in the resistance characteristics of the two thermometers were observed at the triple point of water.     

Characterization of Thermal Conductivity of Carbon Fibers at Temperatures as Low as 10 K

Due to their excellent thermal structural properties, carbon fibers have been extensively applied in the fields of mechanical and aerospace engineering. Many studies have been conducted at room temperature or higher, yet the literature gives very few data on the measurement of thermophysical properties at very low temperatures. The thermal diffusivity of two kinds of carbon fibers was measured by the transient electrothermal technique at very low temperatures (down to 10 K) in the work, the ρCp followed the Debye T3 law dependence quite accurately in agreement with theoretical investigations at very low temperatures(<?10 K). The thermal diffusivity of carbon fiber almost increases linearly with decreasing temperature, but when the temperature drops down below 90 K, the thermal diffusivity rapidly decreases. The thermal expansion mismatch between the different materials present in carbon fibers may influence the change of thermal diffusivity. The relationship between the impurity concentration and the thermal transport of the carbon fibers is discussed.     

Physicochemical Properties of L-Alanine in Aqueous Silver Sulphate Solutions at (298.15, 308.15, and 318.15)?K

Apparent molar volumes ${(\varphi_V)}$ and viscosity B coefficients for L-alanine in (0.005, 0.010, 0.015, and 0.020) mol · dm^?3 aqueous silver sulphate (Ag₂SO₄) solutions were determined from the solution density and viscosity measurements at (298.15, 308.15, and 318.15) K as a function of amino acid concentration. The standard partial molar volumes ${(\varphi_V^0)}$ and experimental slopes ${(S_V^\ast )}$ obtained from the Masson equation were interpreted in terms of solute?Csolvent and solute?Csolute interactions, respectively. To analyze solution viscosities in terms of viscosity B coefficients, the Jones?CDole equation was applied. The structure-making or -breaking ability of the amino acid has also been discussed in terms of the sign of ${(\delta^{2}\varphi_V^0/\delta T^{2})_{P}}$ . The activation parameters of viscous flow for the ternary solutions were also derived and explained in terms of transition state theory.     

Wetting and reaction of molten La with poly- and mono-crystalline MgO at 1323 K

Wetting of poly- and mono-crystalline MgO substrates by molten La was investigated at 1323 K in a high vacuum using a modified sessile drop method. The wettability seems to depend mildly on the substrate orientation but strongly on the surface roughness. The initial contact angles on the smooth (100), (110), and (111) surfaces are 63° ± 1°, 69° ± 1°, and 69° ± 1°, respectively, while on the rough polycrystalline surfaces they are much larger (104° ± 3°). The wetting behavior is dictated by the disruption of the oxide film covering the La surface, the extent of the interfacial reaction and the evolution of the reaction product. A thick layer of La₂O₃ phase formed at the interface and then enwrapped the liquid surface, leading to the recession and warping of the triple line and finally the deterioration in the wettability. On the other hand, magnesium was displaced by the reaction and its evaporation provided additional impetus for the movement of the triple line. Due to different reaction intensities, the wetting behavior of La on the different orientations of the MgO surfaces also showed some discrepancies.