Search

Ionic liquids (ILs), recognized as environmentally friendly green reagents, have good application prospects in many fields. However, their high viscosity has hindered their widespread application. Currently, an effective solution is to introduce a solvent as an additive. In this work, ethanol with different molar fractions was chosen to form working pairs with three ILs ([emim]BF4, [bmim]BF4 and [hmim]BF4), to reduce their viscosities. The densities and viscosities of the three working pairs were obtained in a temperature range of 293.15 to 338.15 K, thereby determining the thermal expansion coefficients. The effects of ethanol on the volumetric and viscometric characteristics of the three ILs are discussed. To further analyze the interactions between ethanol and the ILs, excess mole volume and viscosity deviations were introduced. The interactions between different molecules were stronger than those between the same molecules in the working pairs. This is the main reason why the addition of ethanol reduces the viscosity of the three ILs. Finally, the hard-sphere model was applied to predict the viscosities of the working pairs. Upon introducing an adjustable argument, the average absolute relative deviation of the prediction for the aforementioned three ILs decreased to 4.4%, 5.9%, and 5.0%, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The thermal expansion of a ZrO2-20 mol% Gd2O3 pellet has been systematically investigated using a thermo-mechanical analyzer in the temperature range of 293-1773 K. Variations in the thermal expansion coefficient and density upon temperature change were calculated using the thermal expansion data. The average linear thermal expansion coefficient of the ZrO2-20 mol% Gd2O3 pellet was found to be 9.522 × 10–6 K–1 in the range of 298-1073 K. This value is smaller than that of ZrO2 and larger than that of Gd2O3. Further, with an increase in temperature to 1773 K, the density of ZrO2-20 mol% Gd2O3 pellet was found to decrease to 94.98 % of the initial density at 293 K.

The Al x CoCrCuFeNi (x = 0.25, 0.5, 1, 2) high entropy alloys (HEAs) were prepared by arc melting and spray casting techniques. Their microstructures, hardness, and thermophysical properties such as fusion enthalpy, entropy, thermal diffusion coefficients, thermal expansion coefficients, were investigated. XRD results indicated that Al x CoCrCuFeNi (x = 0.25 and 0.5) alloys were composed of a high-entropy FCC phase and Cu-rich nanophase. As the Al content increased to 1 and 2, the phase structures included the AlNi-rich B2 phase, FeCr-rich A2 phase and Cu-rich nanophase. With the increased Al content, the microstructures of Al x CoCrCuFeNi HEAs transitioned from coarse dendrites to petal-like dendrites, and the grains were continuously refined. Moreover, the Al additions reduced the density whereas increased the Vickers hardness of the alloys. The maximum hardness observed in Al 2 CoCrCuFeNi HEA was approximately 2.4 times greater than that of the Al 0.25 CoCrCuFeNi HEA. The thermal diffusion coefficients of alloys initially increased and subsequently decreased as the temperature elevated. The phase transformation induced by Al content was an effective method for rapidly homogenizing the internal temperature of alloys. Furthermore, the crystal structure, elemental segregation, lattice distortion, enthalpy and entropy of fusion, and lattice vibration frequency all mutually affected the thermal diffusion and expansion coefficients of Al x CoCrCuFeNi HEAs. • The phase composition changed from FCC to FCC + BCC phases with the increase in Al. • The Al additions reduced the density whereas increased the hardness of the alloys. • The thermal diffusion and expansion coefficients of alloys were investigated. [ABSTRACT FROM AUTHOR]

Density, thermal expansion coefficient, surface tension and viscosity of liquid Zr at high temperatures were measured in two Electrostatic Levitation (ESL) facilities. The ground-based tests at NASA MSFC ESL were conducted in vacuum and the space-based tests at JAXA ELF were conducted in Argon atmosphere with both results reported as a function of temperature. The accuracy and precision of each set of the measurement techniques has been reported using a detailed uncertainty analysis. The uncertainties associated with each measurement were used to characterize performance for each facility. Zr samples processed in microgravity showed heavy influence of oxidation which lowered the natural frequency and thus significantly affecting the accuracy of surface tension measurement. The ground-based results are comparable to previously reported literature values. [ABSTRACT FROM AUTHOR]

In this work, the thermophysical properties of four mineral (paraffinic and naphthenic) and four synthetic (polyalphaolefin and ester) base oils are measured. Knowledge of these properties is of vital importance for the correct and optimal formulation and design of lubricants, and for the development of equations of state and transport models that adequately represent their properties. Density, isothermal compressibility, thermal expansion coefficient, dynamic viscosity, pressure–viscosity coefficient, and contact angle were determined. To carry out this work, a pρT apparatus, a rotational viscometer, a falling body viscometer, and a contact angle analyzer were used. Highest densities were found for the polyalphaolefin and ester synthetic oils, increasing around 5% from 0.1 to 100 MPa for all the base oils. The density of the synthetic oils is less dependent on temperature changes. For the expansivity and compressibility of all the base oils, decreases with pressure of up to 35% and 45% were observed. From the contact angle measurements, it was observed that base oils with a higher viscosity grade have a worse wetting. The greatest effect of pressure on the dynamic viscosity was obtained for the naphthenic mineral oil and the lowest effect for the polyalphaolefin oil. Paraffinic and naphthenic oils present the highest universal pressure–viscosity coefficients. [ABSTRACT FROM AUTHOR]

The heat capacity and volumetric characteristics of 0.20Bi2O3⋅хBaO⋅(0.80 – х)B2O3 glasses containing 5, 10, 15, and 20 mol % BaO have been measured in the temperature range 300–1000 K. The results, in combination with the glass transition characteristics found, have been used to calculate the standard thermodynamic functions (Т), H°(T) − (0), S°(T) − (0), and G°(T) − (0); density ρ(T); and thermal expansion coefficient α(T) in the range from T → 0 to 900 K for the glasses and supercooled melts. Having a broad transmission window, as demonstrated by our spectroscopic measurements, the glasses have high crystallization resistance according to differential scanning calorimetry results. [ABSTRACT FROM AUTHOR]

The thermal expansion of a ZrO2-20 mol% Gd2O3 pellet has been systematically investigated using a thermo-mechanical analyzer in the temperature range of 293-1773 K. Variations in the thermal expansion coefficient and density upon temperature change were calculated using the thermal expansion data. The average linear thermal expansion coefficient of the ZrO2-20 mol% Gd2O3 pellet was found to be 9.522 × 10-6 K-1 in the range of 298-1073 K. This value is smaller than that of ZrO2 and larger than that of Gd2O3. Further, with an increase in temperature to 1773 K, the density of ZrO2-20 mol% Gd2O3 pellet was found to decrease to 94.98 % of the initial density at 293 K. [ABSTRACT FROM AUTHOR]

Cobalt and iron-based alloys with tendency to amorphization is a hot topic nowadays due to their unique magnetic and electrical properties. In the present work the differential thermal analysis (DTA) and density measurements of Co48Fe25Si4B19Nb4 alloy (base composition) with small additions of rare earth metals (Nd, Sm, Tb, Yb) are performed. The temperatures of phase transitions in the alloys are determined by DTA. It was found that small additions of rare earth metals (1 and 2 at %) increase solidus temperature and decrease liquidus of the base composition. Small thermal effects that were observed in the alloys with neodymium, terbium and ytterbium in the range 1080–1100°С, may indicate the decomposition of REM-B type compounds. In the alloys with samarium such effects were not found. That means that samarium does not form the Sm2B5 phase in the investigated alloys but goes into solution. Density was studied experimentally in a wide temperature range, including crystalline and liquid states, on an automated setup where the absolute variant of gamma-penetration method was realized. It is shown that temperature dependences of density in crystalline state are nonlinear and in liquid state are well described by linear functions. When melts are overheated above a certain temperature, density hysteresis (incoincidence of heating and cooling curves) appears; that may indicate structural transformations occurring in the melt. It is found that the rare-earth additions increase density of investigated alloys, however, this occurs non-linearly and depends on REM content. Basing on density experimental data, the coefficients of volume expansion and molar volumes are calculated. [ABSTRACT FROM AUTHOR]

In this work, the thermophysical properties of four mineral (paraffinic and naphthenic) and four synthetic (polyalphaolefin and ester) base oils are measured. Knowledge of these properties is of vital importance for the correct and optimal formulation and design of lubricants, and for the development of equations of state and transport models that adequately represent their properties. Density, isothermal compressibility, thermal expansion coefficient, dynamic viscosity, pressure–viscosity coefficient, and contact angle were determined. To carry out this work, a pρT apparatus, a rotational viscometer, a falling body viscometer, and a contact angle analyzer were used. Highest densities were found for the polyalphaolefin and ester synthetic oils, increasing around 5% from 0.1 to 100 MPa for all the base oils. The density of the synthetic oils is less dependent on temperature changes. For the expansivity and compressibility of all the base oils, decreases with pressure of up to 35% and 45% were observed. From the contact angle measurements, it was observed that base oils with a higher viscosity grade have a worse wetting. The greatest effect of pressure on the dynamic viscosity was obtained for the naphthenic mineral oil and the lowest effect for the polyalphaolefin oil. Paraffinic and naphthenic oils present the highest universal pressure–viscosity coefficients.

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Volume change related defects formation mechanisms are an important detracting phenomenon in production of complex shaped cast components. Among different technical alloys, cast iron behaves in a complex manner due to the combined volume change of the formed phases. The liquid and the austenitic phase are contracting while the graphite phase is expanding during the solidification. The complex volume change in combination with complex casting shapes causes a considerable deviation from isotropy in the solidification domain. The mentioned difficulties are considered the main reason why an extensive research work is condensed in the literature within this topic. The multitude of reported experimental set up and the various efforts to interpret the volume change phenomena in terms of density and thermal expansion coefficients makes the results difficult to compare from different sources. With these difficulties in mind, the present paper presents a broad experimental series and measures unidirectional linear deformation of an industrially spread lamellar cast iron alloy system (Fe-C-2Si) using the push-rod based dilatometer technique. The measurements are divided into two major groups with respect to the liquid iron deformation over the liquidus temperature line, and the austenite deformation below the solidus temperature line. The obtained results are interpreted as thermal expansion coefficients, density variation slopes, and density data at the liquids and solidus temperature. The obtained results are compared with literature data and with calculated values by the Thermo Calc software.

This work aims to present results of the measurements of the density of the anhydrous ethanol fuel in the liquid phase, and the following thermal properties: thermal expansion coefficient and isothermal compressibility factor, in the temperature range of 277.15 K to 313.15 K and for pressures up to 15.0 MPa are presented. The density measurements were performed using a pycnometer that was calibrated, which presents a volume uncertainty of 0.020 cm3. Correlations were obtained for density, thermal expansion coefficient, and the isothermal compressibility factor. A system of measurement was developed capable of realizing density measurements using a pycnometer and a pressure cell with low uncertainties in different pressures and temperatures. [ABSTRACT FROM AUTHOR]

The ionic liquid (IL) of 1-hexyl-3-methylimidazolium acetate is widely used in chemical and bio-chemical processes. In this work, due to the high viscosity of IL, the promising chemicals (i.e., N, N-dimethylacetamide, N, N-dimethylformamide, and dimethyl sulfoxide) were selected as the additives to lower IL viscosity. The thermophysical properties of density and viscosity for IL with solvents were measured using a digital vibrating U-tube densimeter and an Ubbelohde capillary viscometer from 303.15 to 338.15 K at atmospheric pressure (0.0967 MPa), respectively. The influences of the solvents on the thermophysical properties of ionic liquid were quantitatively studied. Furthermore, based on the measurement values, the derived properties of excess molar volumes, thermal expansion coefficient, and the energy barrier were calculated, and the results showed that the mixture composition had great impact on excess volume change and viscosity. The hard-sphere model was employed to reproduce the viscosity. The infrared spectroscopy was performed to study the chemical structure to further understand the interactions between IL and the solvents. [ABSTRACT FROM AUTHOR]

Ionic liquids, which are extensively known as low-melting-point salts, have received significant attention as the promising solvent for CO2 capture. This work presents the synthesis, thermophysical properties and the CO2 absorption of a series of ammonium cations coupled with carboxylate anions producing ammonium-based protic ionic liquids (PILs), namely 2-ethylhexylammonium pentanoate ([EHA][C5]), 2-ethylhexylammonium hexanoate ([EHA][C6]), 2-ethylhexylammonium heptanoate ([EHA][C7]), bis-(2-ethylhexyl)ammonium pentanoate ([BEHA][C5]), bis-(2-ethylhexyl)ammonium hexanoate ([BEHA][C6]) and bis-(2-ethylhexyl)ammonium heptanoate ([BEHA][C7]). The chemical structures of the PILs were confirmed by using Nuclear Magnetic Resonance (NMR) spectroscopy while the density (ρ) and the dynamic viscosity (η) of the PILs were determined and analyzed in a range from 293.15K up to 363.15K. The refractive index (nD) was also measured at T = (293.15 to 333.15) K. Thermal analyses conducted via a thermogravimetric analyzer (TGA) and differential scanning calorimeter (DSC) indicated that all PILs have the thermal decomposition temperature, Td of greater than 416K and the presence of glass transition, Tg was detected in each PIL. The CO2 absorption of the PILs was studied up to 29 bar at 298.15 K and the experimental results showed that [BEHA][C7] had the highest CO2 absorption with 0.78 mol at 29 bar. The CO2 absorption values increase in the order of [C5] < [C6] < [C7] anion regardless of the nature of the cation.

Volume change related defects formation mechanisms are an important detracting phenomenon in production of complex shaped cast components. Among different technical alloys, cast iron behaves in a complex manner due to the combined volume change of the formed phases. The liquid and the austenitic phase are contracting while the graphite phase is expanding during the solidification. The complex volume change in combination with complex casting shapes causes a considerable deviation from isotropy in the solidification domain. The mentioned difficulties are considered the main reason why an extensive research work is condensed in the literature within this topic. The multitude of reported experimental set up and the various efforts to interpret the volume change phenomena in terms of density and thermal expansion coefficients makes the results difficult to compare from different sources. With these difficulties in mind, the present paper presents a broad experimental series and measures unidirectional linear deformation of an industrially spread lamellar cast iron alloy system (Fe-C-2Si) using the push-rod based dilatometer technique. The measurements are divided into two major groups with respect to the liquid iron deformation over the liquidus temperature line, and the austenite deformation below the solidus temperature line. The obtained results are interpreted as thermal expansion coefficients, density variation slopes, and density data at the liquids and solidus temperature. The obtained results are compared with literature data and with calculated values by the Thermo Calc software. [ABSTRACT FROM AUTHOR]

Physical properties, such as density, refractive index and viscosity, of an aqueous sodium salt of (S)-2-amino-3-phenylpropionic acid (L-phenylalanine, Na-Phe) were investigated in this work. These properties were measured over a temperature range of 298.15–343.15 K at atmospheric pressure. The mass fractions (w) of Na-Phe were 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35 and 0.40. The analysis of the experimental data showed that the values of density, refractive index and viscosity decreased with increasing temperature at any constant concentration of Na-Phe. However, these values increased with increasing concentration at any constant temperature. The density values were used to estimate the thermal expansion coefficient. The thermal expansion coefficient increased slightly with increasing temperature and concentration. The density and refractive index data were correlated using a modified Graber equation, while, the viscosity data were correlated using a modified Vogel–Tamman–Fulcher (VTF) equation. In all the cases, quantitative analyses of the influence of temperature and concentration were performed.

The ionic liquid (IL) of 1-hexyl-3-methylimidazolium acetate is widely used in chemical and bio-chemical processes. In this work, due to the high viscosity of IL, the promising chemicals (i.e., N, N-dimethylacetamide, N, N-dimethylformamide, and dimethyl sulfoxide) were selected as the additives to lower IL viscosity. The thermophysical properties of density and viscosity for IL with solvents were measured using a digital vibrating U-tube densimeter and an Ubbelohde capillary viscometer from 303.15 to 338.15 K at atmospheric pressure (0.0967 MPa), respectively. The influences of the solvents on the thermophysical properties of ionic liquid were quantitatively studied. Furthermore, based on the measurement values, the derived properties of excess molar volumes, thermal expansion coefficient, and the energy barrier were calculated, and the results showed that the mixture composition had great impact on excess volume change and viscosity. The hard-sphere model was employed to reproduce the viscosity. The infrared spectroscopy was performed to study the chemical structure to further understand the interactions between IL and the solvents.

Abstract Densities ρ and speed of sound u for the binary liquid mixtures of dipropylene glycol dimethyl ether (1) + 2-propanol (2), +1-butanol (2) and +2-butanol (2) have been measured at temperatures T = (288.15, 293.15, 298.15, 303.15 and 308.15) K and experimental pressure P = 0.1 MPa over the whole composition range. Experimental densities and speed of sound data has been used to determine excess molar volumes V m E , isentropic compressibility κ S , molar isentropic compressibility K s,m and their excess counterpart excess isentropic compressibility K S , m E at different temperatures. Thermal expansion coefficient along with its excess function has been reported. Deviations in intermolecular free length and deviations in acoustic impedance have also been reported. The variations of the parameters with concentration and temperature have been discussed t have insight into the intermolecular interactions prevailing in the mixtures chosen for the present study. Highlights • New data on excess molar volumes for DPGDME + alkanols binary liquid mixtures • Positive deviations in excess molar volumes suggest breaking of structure. • Positive excess isentropic compressibilities increase with increase in temperature. • Excess thermal expansion coefficient indicates weak interactions in binary liquid mixtures. • Intermolecular free length and acoustic impedance have been determined. [ABSTRACT FROM AUTHOR]

The effect of silicon addition to aluminum on the thermophysical properties of Al was experimentally investigated. Thermal diffusivity, heat capacity, density, and thermal expansion of sintered Al-Si samples with Si content ranging 0–8 wt% were measured. For U-Mo/Al dispersion fuel for research reactors, an addition of Si (up to 8 wt% Si) to the Al matrix has been adopted as a method to reduce the formation of interaction layer between the U-Mo and the Al. In this study, the Si-added Al matrix was simulated by using a powder metallurgical method, in which an Al powder and a Si powder were mixed and sintered. All measured properties decreased with the addition of Si. The effect was most pronounced in thermal diffusivity while the decreases in heat capacity and density were relatively insignificant. The measured thermal conductivity from the present study was higher than those measured data for alloy samples available in the literature to the differences in the fabrication method. All measured data including this study, however, were lower than the prediction by the Bruggeman model. It is because the model assumes an ideal heat-transfer conditions such as spherical particles, homogeneous particle distribution, perfect bonding between Al and Si. [ABSTRACT FROM AUTHOR]

The densities of 1-alkyl-3-methylimidazolium acetate [C 3 mim][Ac] and [C 4 mim][Ac] aqueous solution were measured in the concentration from 0.05000 to 3.000 mol·kg − 1 over the temperatures range from 283.15 to 323.15 K. The coefficient of thermal expansion of the solution, α, apparent molar volume, ϕ V B , the apparent molar expansibility of the solute , ϕ E and the partial molar volume were calculated. The Pitzer's model was used to establish an equation to describe the volumetric properties and the corresponding parameters β MX (0) V , β MX (1) V and C MX V were obtained. Comparing the values of V B 0 obtained by Pitzer's method with those values of V ϕ 0 calculated by Redlich and Meyer's shows that Pitzer's formulism can be applied in the aqueous solution of ionic liquids. [ABSTRACT FROM AUTHOR]

Density (ρ), speed of sound (U), and the derived magnitudes of two diethylmethylammoniumionic liquids (ILs) against temperature have been studied in this work. The chosen ILs were diethylmethylammonium trifluoromethanesulfonate [C2C2C1N][OTf] and diethylmethylammonium methanesulfonate [C2C2C1N][MeSO3]. In order to analyze the influence of water content, saturated and dried samples of these ILs were studied. The ILs were dried using a vacuum pump, and the saturation level (28% and 6% in weight for [C2C2C1N][MeSO3] and [C2C2C1N][OTf], respectively) was achieved by keeping the ILs in an open bottle at ambient temperature. Direct measurements of density and speed of sound were taken with an Anton Paar DSA 5000. Linear equations were used to express the correlation of both properties with temperature, and the thermal expansion coefficient, αp, and the adiabatic bulk modulus constant, KS, have been also obtained. Additionally, results were compared with previous literature data in order to have a deeper understanding of the liquid properties and detect possible anomalous behaviors. The effect of water content is different on both properties. Thus, the density of the samples slightly increases when water is removed, whereas the opposite behavior was found with regard to the speed of sound, which decreased when the water content was completely removed.

The function of copper (Cu) inside amalgam is to increase hardness and impact force and to decrease thermal expansion coefficient. In general, amalgam which is used in dentistry and available in the market is contain Cu 22%, while the maximum Cu concentration is 30%. It is necessary to determine the concentration Cu does generate the best physical properties to be used as dental restorative agent. Amalgam is made by mixing blended-metal Ag-Sn-Cu (with Cu concentration of 13%, 21%, 22%, and 29%) and Hg, stirred manually in a bowl for 15 minutes,leave it in temperature 27°C for 24 hours to become hardened. The result of X-Ray Diffractometer (XRD), analyzed by Rietveld method and Rietica program, shows amalgam with Cu 29% concentration for Cu3Sn compound density is 31.790 sma/Å3, for Ag2Hg3 compound is 41.733 sma/ Å3, a Cu3Sn relative weight percentage of 43.23%, Ag2Hg3 of 54.54%, Cu 7Hg6 of 2.23% and hardness of Cu 29% is 90.700 ± 0.005 kgf/mm2. These numbers are the highest values on Cu 29% concentrations compared to other copper concentration variants. Whereas amalgam thermal expansion coefficient on Cu 29% is (2.17 ± 0.91)10-3 mm/°C is the lowest value compared to other Cu concentration. The conclution is that adding Cu concentration into amalgam will increase density value, Cu3Sn relative weight percentage, hardness level and will decrease amalgam thermal expansion coefficient. Amalgam 29% Cu concentration has better physical properties compared to amalgam Cu 22% concentration.

The solubility and volumetric properties of H 2 and heavy hydrocarbons are important to the design of many chemical processes. In this paper, a simplified Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) is chosen to model the solubility and volumetric properties of H 2 /heavy alkanes and H 2 /bitumen mixtures. The number of reduced density roots given by the simplified PC-SAFT is discussed and a robust procedure is employed to solve for the root with the lowest Gibbs free energy. The development of new H 2 parameters and the k ij correlation of H 2 -heavy alkane pairs for the simplified PC-SAFT is completed using extensive experimental data. The new parameters are applied with a developed bitumen characterization method to predict H 2 solubility in Athabasca Bitumen. The average absolute deviations (AADs) between the measured solubility data and the modeling results are within 0.57% for the five H 2 /heavy alkane systems and 0.69% for the H 2 /Athabasca bitumen systems. Finally, the density, thermal expansion coefficient, and compressibility of the systems are predicted over wide ranges of temperature and pressure. [ABSTRACT FROM AUTHOR]

Based on density measurement, we appraised and reported partial molar volumes and thermal expansion coefficients along with their excess values for six binary mixtures of 1-propanol or iso-butanol with vinyl, ethyl and tert-butyl acetate. Temperature range was (293.15–313.15) K and whole range of composition at ambient pressure (0.087 MPa) is considered. Results showed that excess molar volumes for all mixtures are positive and increased with temperature. Also the excess thermal expansion coefficients were positive and demonstrate small positive sensitivity to temperature change. Results are explained based on intermolecular interactions and also Redlich–Kister equations were fitted to excess molar volume data. [ABSTRACT FROM AUTHOR]

Density, sound velocity and refractive index of binary mixtures of water + 1,2-dimethoxyethane mixtures were measured over the whole composition range and at the temperature interval from 293.15 to 323.15 K. Obtained density data for the pure components agree, within experimental error, with published values. However, in the case of binary mixtures, strong discrepancies with values calculated from the equation proposed in the literature for this system are found. Excess functions, isentropic compressibility coefficients and thermal expansion coefficients were calculated from experimental data. Partial molar volumes were obtained employing the exponential representation previously proposed by us which shows better results than the usual polynomial approach. Results are discussed on the grounds of the molecular characteristics obtained from Raman and NMR spectroscopy determinations on this system. [ABSTRACT FROM PUBLISHER]

The densities of ten binary mixtures of biodiesel made from rapeseed oil and ethanol have been measured for eight temperatures within the range between 273.15 K and 333.15 K, using an Anton Paar DMA 4500 M densimeter. The excess molar volume has been calculated from experimental densities. Variation of mixtures volumes was low, but measurable. It was observed that the excess molar volume was positive for all studied mixtures, due to increased physical interactions between fatty acid methyl esters and ethanol. Density variation was modeled by polynomial regression and the thermal expansion coefficient, as well as its excess value, were estimated. The excess molar volume and excess thermal expansion coefficient results were fitted to the Redlich–Kister type polynomial equation to obtain the regression coefficients and estimate the standard deviations and correlation coefficients between experimental and calculated results. [ABSTRACT FROM AUTHOR]

[Display omitted] • Volume property of LiBO 2 (aq) agaist temperature and molality was revealed for the first time. • Single-salt parameters of Li[B(OH) 4 ] at 5 K temperature intervals from 283.15 to 363.15 K were obtained. • The temperature-dependence equations and their coefficients of the single-salt parameters were established. Volume properties of salt lake solution are of great significance in constructing the thermodynamic model of the salt lake brine system and promote the comprehensive utilization of salt lake resources. In this paper, LiBO 2 (aq) densities from 0.08083 to 0.75731 mol·kg−1 were determined experimentally at 5 K temperature intervals from 283.15 to 363.15 K and 101 kPa using a precise digital vibrating-tube densimeter. The apparent molar volume (V ϕ) and the thermal expansion coefficient (α) were derived based on the experimental data. The 3D diagrams of the apparent molar volume and the thermal expansion coefficient against molality and temperature were demonstrated. According to the Pitzer thermodynamic model of apparent molar volume of electrolyte, the Pitzer single-salt parameters β MX (0) ν , β MX (1) ν , β MX (2) ν , C MX ν of LiB(OH) 4 and their temperature-dependence coefficients (p = C o + C 1 ln T /298.15 + C 2 (T -298.15) + C 3 /(620- T) + C 4 /(T -227) were established for the first time. A comparison between the predictive and experimental data indicates that the experimental data and the parameters obtained in this work are reliable. [ABSTRACT FROM AUTHOR]

The densities of aqueous mixtures of aminoethylethanolamine (CAS #000111-41-1) were measured over the entire compositional range at temperatures of 283.15-343.15 K. The results of these measurements were used to calculate excess molar volumes and isobaric thermal expansion coefficients, and partial molar and apparent molar volumes and excess isobaric thermal expansion coefficients were subsequently derived. The excess molar volumes were correlated as a function of the mole fraction using the Redlich-Kister equation. Temperature dependences of the Redlich-Kister coefficients are also presented. The partial molar volumes at infinite dilution of AEEA in water were determined using two different methods. In addition, the solution density was correlated using a Joubian-Acree model. Aqueous solutions of AEEA exhibit similar properties to the aqueous solutions of other alkanolamines (like monoethanolamine) used in acid gas sweetening. [ABSTRACT FROM AUTHOR]

Abstract: In order to select the most suitable ionic liquids (ILs) for certain applications it is necessary to know some of their thermophysical properties, such as density or viscosity. In this work we have performed density measurements of two ILs 1-ethyl-3-methylimidazolium ethylsulfate and 1-(2-methoxyethyl)-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide in a broad range of temperature and pressure ((278.15 to 398.15)K and up to 120MPa). From these measurements we have obtained other volumetric properties such as isothermal compressibility and isobaric thermal expansivity. In addition, density values were predicted using the method proposed by Gardas and Coutinho and also that proposed by Jacquemin et al., obtaining a good agreement with experimental values. [Copyright &y& Elsevier]

Densities and refractive indices have been measured for binary mixtures of 1-propyronitrile-3-hexylimidazolium bromide + ethanol in the temperature range 293.15-323.15 K. From the experimental data the excess molar volume V, refractive index deviation Δ n, and the coefficient of thermal expansion α were calculated and fitted to fifth- and third-order Redlich-Kister type equations, respectively. Using the measured densities, the apparent molar volumes ( V), limiting apparent molar volumes ( $V_{\phi}^{0}$) and limiting apparent molar expansivities ( $E_{\phi} ^{0}$) were also determined and the details are discussed. [ABSTRACT FROM AUTHOR]

The phase-transition studies such as the variation of density with temperature is carried in four newly synthesized compounds namely N-(p-n-decyloxybenzylidene)-p-n-octadecylaniline, 10O.18, N-(p-n-octadecyloxybenzylidene)-p-n-octadecyl aniline, 18O.18, (p-n-phenylbenzylidene)-p-n-octadecyl aniline, PB18A and terephthalyidene-bis-p-n-octadecylaniline, TB18A. These compounds exhibit a variety of phase variants such as isotropic-to-smectic-F (Iso-SmF) in 10O.18 and 18O.18, isotropic-to-smectic-A to-smectic-B (SmA-SmB) in PB18A and Isotropic-to-smectic-C to-smectic-I to-smectic-F (SmC-SmI-SmF) in TB18A. The density and thermal expansion coefficient results reveal that all the phase transitions studied in this article show first/second-order nature. The estimated values like density jumps and the thermal expansion coefficient maxima from the density data at the transitions exhibit characteristic changes. The results are discussed in light of the body of the data available. [ABSTRACT FROM AUTHOR]

We report an experimental search for the enhancement of the isobaric thermal expansion coefficient ( β) of superfluid He near the superfluid transition by a heat current ( Q). The experiment was carried out using the hot volume technique at constant sample pressure of 1 bar. Liquid helium was contained in a thermal conductivity cell, and a constant heat current, Q=10 or 100 μW/cm, was supplied from below through the sample column. We performed a sample density calculation based on existing helium properties known in the literature and a proposed enhancement Δ β( Q). Both calculations, with or without the β enhancement, agree qualitatively with the measurement. The lack of definitive differentiation indicates that the β enhancement cannot be definitively resolved by our measurement in spite of applications of high-resolution thermometry and pressure regulation. [ABSTRACT FROM AUTHOR]

Abstract: The non-linearity parameter B/A is estimated for a number of liquid crystal materials of the type N-(p-n-alkoxy benzylidene)-p-n-alkyl anilines, popularly known as nO.m, where n and m are the aliphatic chains on either side of the rigid core, which can be varied from 1 to 18 to realize a number of LC materials with a variety LC phase variants. The B/A values are computed from both density and sound velocity data following standard relations reported in literature. This systematic study in a homologous series provides an opportunity to study how this parameter behaves with (1) either the alkoxy and/or alkyl chain number, (2) with the total chain number (n+m), (3) with increase in molecular weight and (4) whether the linear relations reported in literature either with αT [thermal expansion coefficient (α) and temperature (T)] and sound velocity (u) will hold good or not and if so to what extent. The results are discussed with the body of data available in literature on liquids, liquid mixtures and other LC materials. [ABSTRACT FROM AUTHOR]

Abstract: Ionic liquids are a class of fluids that requires the attentions of experimentalist and theoreticians. In a new project on synthesis and characterization of new and not-so-new ionic liquids, the study of several thermophysical properties of these liquids was started, namely binary diffusion, electrical conductivity, heat capacity, surface tension, viscosity and thermal conductivity. Among others we will study 1-n-butyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide, ([C4mim][NTf2]), 1-n-butyl-3-methyl-imidazolium dicyanamide, ([C4mim][dca]), 1-ethyl-3-methyl-imidazolium ethylsulfate, ([C2mim][EtOSO3]) and methyltrialkylammonium dicyanamide [Aliquat®336-derived][dca], and in the case of diffusion, their mixtures with water. It is the purpose of this paper to report data on the density, using vibrating tube densimetry, infinite dilution diffusion coefficients, using the Taylor dispersion method, heat capacity, using DSC equipment and surface tension, using the Wilhelmy plate method. Density measurements were performed at atmospheric pressure between 293 and 363K and several isotherms, depending on the stability of the compound, up to 60MPa, with an uncertainty of 0.4%. Measurements were performed at 298.03K for the infinite dilution measurements, with an uncertainty of 1.3–3.5%, for temperatures between 300 and 370K for heat capacity, with an uncertainty better than 1.5%, and between 292 and 395K for surface tension, with an uncertainty of 1.5–1.8%. A brief analysis of the potential of the fluids studied as engineering heat transfer fluids, namely its heat storage capacity was also performed. [Copyright &y& Elsevier]

Abstract: The surface tension and density of almost all members of the 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amides family, [C n mim][Ntf2], with 2≤ n ≤14 were measured for the first time up to 532K and 473K, respectively. The large number of ionic liquids studied within this family and the broad interval of working temperature enabled us to show evidence for a thermodynamic anomaly in the thermal expansivity of these ionic liquids (minima in α p versus T). The minima themselves have never been witnessed before. The data in this extended temperature range also permitted us to discuss the location of hypothetical normal boiling and critical points. [Copyright &y& Elsevier]

Abstract: The thermophysical properties of 1-alkylpyridinium bis(trifluoromethylsulfonyl)imide, [C n py][Tf2N] ionic liquids where n =4, 8, 10, or 12 have been determined. Density ρ, and dynamic viscosity η, were determined at T =(293.15 to 353.15)K and refractive index nD , was measured at T =(293.15 to 333.15)K. Empirical correlations are proposed to represent the present experimental results. The values of the coefficient of thermal expansion were calculated from the experimental density values. The thermal decomposition temperature, Td was also determined using thermogravimetric analyzer (TGA) at a heating rate of (10 and 20)K·min−1. [Copyright &y& Elsevier]

Abstract: Densities of the binary mixtures of (diethylcarbonate+acetophenone), (diethylcarbonate+1-hexanol), and (acetophenone+1-hexanol) were measured at T =(293.15, 303.15, 313.15, and 323.15)K for the liquid region and at ambient pressure over the whole composition range using a vibrating U-tube densimeter. The excess molar volumes , partial molar volumes , limiting partial molar volumes , thermal expansion coefficients α, and their excess values α E, and isothermal excess molar enthalpy–pressure derivative , were calculated from experimental densities. The binary data of and α E were correlated as a function of the mole fraction by using the Redlich–Kister type function to determine the fitting parameters and the standard deviations. The experimental data of the constituent binaries are analysed to discuss the nature and strength of intermolecular interactions in these mixtures. [Copyright &y& Elsevier]

PbO based phosphate glasses having composition 40P2O5·12Al2O3·6B2O3·9PbO· xNa2O·(33− x)K2O ( x=0−33) [ F=Na/(Na+K)] have been prepared using conventional melt quench technique. Density, morphology, thermal expansion coefficient (α) and glass transition temperature ( T g) were studied as a function of Na/(Na+K) ratio. Formation of transparent, bubble free and clear glass was observed up to x=18 mol%. Density was found to vary from 2.70 to 3.69 g cm−3. The significant changes were noticed in external morphologies at temperatures corresponding to softening, half ball and melting points under high temperature microscope for three compositions ( x=0, 10 and 15 mol%). These glasses recorded the softening and half ball temperatures in the range 454–470°C and 523–576°C respectively and melting temperatures agree well with DTA studies within the experimental limits. Glass transition temperature showed a broad maxima while thermal expansion coefficient (TEC) a broad minima around Na/(Na+K)=0.54. This behaviour is explained on the basis of bond formation/phase separation. [ABSTRACT FROM AUTHOR]

Abstract: Density measurements were performed near the smectic C (SmC)-nematic (N1)-nematic (N2)-isotropic (I) phase transitions for HOBA liquid crystal. A discontinuity in the density values at the SmC–N1 and N2–I phase transitions was observed. From a thermodynamic point of view these phase transitions are considered to be first order. An additional small change in the density data was observed in the vicinity of the N1–N2 phase transition. This experimental result confirms the existence of these nematic phases previously reported in the literature. Furthermore, the thermal expansion coefficient (β) was also calculated, exhibiting a large peak at the transition. This behavior can be interpreted as an indication that the transition N1/–N2 is weakly first order. [Copyright &y& Elsevier]

Abstract: Densities of the binary liquid mixtures of (2-methoxyethanol+1-propanol, or 2-propanol, or 1,2-propandiol) have been measured over the entire range of compositions at temperatures from (293.15 to 343.15)K and ambient pressure 81.5kPa, using a vibrating-tube densimeter. The excess molar volumes , thermal expansion coefficients α, and their excess values α E, and isothermal coefficient of pressure excess molar enthalpy , were calculated from experimental densities. The excess molar volume is positive for (2-methoxyethanol+1-propanol) and becomes more positive with increasing temperature. The excess molar volume for (2-methoxyethanol+2-propanol) shows a S-shaped dependence on composition with positive values in the 2-propanol rich-region and negative values at the opposite extreme. With increasing temperature from (293.15 to 313.15)K, it increases but beyond this range with increasing temperature from (313.15 to 343.15)K it decreases. The excess molar volume is negative for (2-methoxyethanol+1,2-propandiol) and becomes more negative with increasing temperature. The excess molar volumes were correlated with a Redlich–Kister type equation. [Copyright &y& Elsevier]

Abstract: A polycrystalline sample of BaSnO3 was prepared from SnO and BaCO3 powders by simple solid-state reactions. The thermal expansion coefficient, heat capacity, thermal diffusivity, thermal conductivity, elastic modulus, Debye temperature, and micro-Vickers hardness were measured. The crystal structure of BaSnO3 is of the cubic perovskite type with a lattice parameter of 0.4116nm at room temperature. The sample bulk density is 95% of the theoretical density. The average linear thermal expansion coefficient is 9.3×10−6 K−1 in the temperature range between 300K and 1773K. The value of Young''s modulus is 244GPa. The thermal conductivity at room temperature is 9.7Wm−1 K−1. [Copyright &y& Elsevier]

Densities of 1-propanol&ThickSpace;+&ThickSpace;dibromomethane, or +bromochloromethane, or +1,2-dichloroethane, or&ThickSpace;+1-bromo-2-chloroethane binary mixtures were measured at 288.15, 298.15 and 308.15&ThickSpace;K, over the entire composition range. Thermal expansion coefficients, α, and excess molar volumes, , were calculated. Moreover, densities at 298.15&ThickSpace;K and pressures up to 2&ThickSpace;×&ThickSpace;10 7 &ThickSpace;Pa were determined for the same mixtures. Isothermal compressibilities, κT, of the pure liquids and their mixtures were obtained. [ABSTRACT FROM AUTHOR]

Cu-SiCp composites made by the powder metallurgy method were investigated. To avoid the adverse effect of Cu-SiCp reaction, sintering was controlled at a reaction temperature less than 1032 K. Electroless plating was employed to deposit a copper film on SiCp powder before mixing with Cu powder in order to improve the bonding status between Cu and SiC particles during sintering. It was found that a continuous copper film could be deposited on SiCp by electroless copper plating, and a uniform distribution of SiCp in Cu matrix could be achieved after the sintering and extrusion process. The mechanical properties of Cu-SiCp composites with SiCp contents from 0.6 to 10 wt% were improved evidently, whereas electrical properties remained almost unchanged as compared with that of the pure copper counterpart. In the electrical discharge machining (EDM) test, the as-formed composite electrodes exhibited a character of lower electrode wear ratio, justifying its usage. The optimum conditions for EDM were Cu–2 wt% SiCp composite electrode operating with a pulse time of 150 μsec. [ABSTRACT FROM AUTHOR]