Experimental Dynamic Viscosities Research Articles

Combined thermodynamic and theoretical study on ether-functionalized ionic liquid mixture systems of [MOEmim][TFSI] with ACN/GBL

Ether-functionalized ionic liquids (ILs) have a higher fluidity and are widely used in a variety of applications due to the introduction of the ether group. In order to better understand the relationship between properties and internal interactions of ether-based ILs, we prepared two ether-functionalized ILs 1–2-methoxyethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide ([MOEmim][TFSI]) with acetonitrile (ACN) or γ-butyrolactone (GBL) mixture systems, and investigated the changes of their thermodynamic properties and internal interaction behaviors over the entire concentration range. First, the thermodynamic properties such as dynamic viscosity, density and electrical conductivity of the two mixture systems were measured from 288.15 K to 343.15 K. The excess molar volume (VE), and viscosity deviation (Δη) were calculated by using the measured experimental density and dynamic viscosity data, which can provide microscopic information on the interactions. Further, the intermolecular interactions of the mixture systems were evaluated by density functional theory (DFT) calculations. The sigma–profile (σ–profile) provided insight into the hydrogen bonds (H-bonds) and molecular surfaces interactions. We also used molecular dynamics simulations (MD) to study ILs mixtures in many different solvent concentrations, thereby providing a microscopic and macroscopic characterization of fluid structure, molecular aggregation, and intermolecular forces.

Some experimental and theoretical studies of diethylene glycol diethyl ether and 2-alkanol mixtures

Experimental density and dynamic viscosity data for the diethylene glycol diethyl ether +2-alkanol (C3 to C6) mixtures have been published at 293.15 K, 303.15 K, 313.15 K, and 323.15 K and at pressure of 0.1 MPa. Excess molar volume and deviation in dynamic viscosity were obtained from experimental data and correlated with Redlich–Kister equation, from the values obtained, the interaction forces were studied. Perturbed chain-statistical associating fluid theory equation of state was used for modeling the density for pure fluids and mixtures. Free volume theory coupled to Perturbed chain-statistical associating fluid theory equation of state was used to modeling the viscosity of pure fluids and mixtures; in the case of binary mixtures, we proposed a simple mixing rule and used the Pourabadeh et al. mixing rule. Good results in the prediction and correlation of experimental liquid density and dynamic viscosity for binary mixtures were obtained, 0.12% and 2.28%, respectively.

Entropy scaled viscosities of choline-chloride-based deep eutectic solvents using a cubic EoS with volume translation

The present modeling work formally introduces, for the very first time, the application of the residual-entropy scaling approach to adequately represent the dynamic viscosity of deep eutectic solvents (DESs) as a function of temperature and density. In doing so, diverse unreduced and reduced viscosity forms (total viscosity, Rosenfeld and dilute gas) were verified and compared. The use of a cubic equation of state (CEoS: Soave-Redlich-Kwong or Peng-Robinson) served here to provide sufficiently accurate residual entropy data required by the present scaling procedure. Experimental DES density data were also modeled by applying a modified Mathias volume translation to the density data originally obtained from the two CEoS during the present scalings. The resulting modeling approach was sucessfully validated during the representation of experimental dynamic viscosities and mass densities of three of the most representative choline chloride-based DESs: ChCl:Urea(1:2), ChCl:Ethylene Glycol(1:2) and ChCl:Glycerol(1:2) within a temperature range varying from 10 to 100 °C and at pressures from 1 to 1,000 bar.

Semi-empirical correlations and an artificial neural network for liquid dynamic viscosity of low GWP refrigerants

In this work, simple semi-empirical correlations to describe the temperature and the pressure dependence of the dynamic viscosity of low GWP refrigerants, namely HydroFluoroOlefins (HFOs) and HydroChloroFluoroOlefins (HCFOs), in the liquid phase are presented. Firstly, the experimental liquid dynamic viscosity data available in scientific literature and databases were collected and statistically analyzed. From the data collected for low pressures, the Latini et al. (2002, 1990) correlation for the dynamic viscosity of liquid refrigerants in saturated conditions was re-fitted and constants expressly dedicated to the studied low GWP refrigerants were obtained. Then, the proposed temperature-dependent correlation was modified to represent liquid dynamic viscosity dependence on pressure. In addition, an artificial neural network was developed to predict the dependence of the liquid viscosity of the studied refrigerants on temperature and pressure. This model was trained, validated, and tested for the selected dataset. The results of the proposed correlations and the multi-layer perceptron neural network were compared with the liquid viscosity calculations provided by some of the most well-known literature correlations and REFPROP 10.0, proving the accuracy of the proposed models for engineering applications.

Investigation of stiffness and damping coefficients in fluid film bearing with bio-oils and mineral-based oil

Rotating machinery utilizes fluid film bearings because of their good load carrying capacity and inherent damping properties. Fluid film bearings offer stiffness and damping parameters to ensure dynamic stability. The damping and stiffness characteristics of oil film significantly change the critical speed and unbalance response of the rotor. The damping and stiffness coefficients (direct, cross-coupled) may lead to system instability, also known as self-excited vibrations. Bio-oils have good tribological and physiochemical properties. They are also environment-friendly and bio-degradable. In this work, bio-oils (rapeseed, palm olein, and soybean) are evaluated in terms of their dynamic characteristics to that of mineral-based SAE40 lubricant for journal-bearing applications. The analytical extraction of damping and stiffness coefficients is performed based on the experimental dynamic viscosity data at different temperatures. In comparison to SAE40, the bio-oils have shown improved responsiveness. Bio-oils showed lower cross-coupled stiffness coefficients than SAE40, the primary source of rotor instability. The main contribution of this study is that it provides damping and stiffness coefficients for various bio-oils at different eccentricity ratios and viscosities for different types of oils. This may be used to characterize the dynamic properties of the fluid film bearing under various operating circumstances. It is concluded that the difference in cross-coupled stiffness favors bio-oils. Whereas, the difference in cross-coupled damping favors SAE40 by around 6%. This discrepancy is decreased to less than 2% for all oil’s final eccentricity ratio values (bio-oils and SAE40).

A van der Waals-EoS-based model for the dynamic viscosity of ionic liquids

A density-independent thermodynamic model was presently developed to adequately represent the dynamic viscosity of pure ionic liquids (ILs). The present model adopts the simple form of the van der Waals equation of state under the basis of a previously established phenomenological similarity between the P-V-T and T-η-P surfaces for non-ionic fluids; however, we found that, in the particular case of pure ionic liquids, the surface P−f−T (where f is the fluidity, the reciprocal of viscosity) rather than the T-η-P surface conforms much better to the P-V-T surface. The resulting model was successfully validated during the representation of experimental dynamic viscosities of three families of imidazolium-based ILs ([CXmim][BF4], [CXmim][PF6] and [CXmim][Tf2N]), four pyridinium-based ILs ([bmpy][BF4], [empy][EtSO4], [Et2Nic][EtSO4] and [hemmpy][Tf2N]) and two ammonium-based ILs ([cpmam][MeSO4] and [4bam][doc]) within a temperature range varying from 0 to 80 °C and at pressures from 1 up to 3,000 bar thus covering a wide viscosity range of 10–19,610 mPa-s.

Investigations of Liquid Steel Viscosity and Its Impact as the Initial Parameter on Modeling of the Steel Flow through the Tundish.

The paper presents research carried out to experimentally determine the dynamic viscosity of selected iron solutions. A high temperature rheometer with an air bearing was used for the tests, and ANSYS Fluent commercial software was used for numerical simulations. The experimental results obtained are, on average, lower by half than the values of the dynamic viscosity coefficient of liquid steel adopted during fluid flow modeling. Numerical simulations were carried out, taking into account the viscosity standard adopted for most numerical calculations and the average value of the obtained experimental dynamic viscosity of the analyzed iron solutions. Both qualitative and quantitative analysis showed differences in the flow structure of liquid steel in the tundish, in particular in the predicted values and the velocity profile distribution. However, these differences are not significant. In addition, the work analyzed two different rheological models—including one of our own—to describe the dynamic viscosity of liquid steel, so that in the future, the experimental stage could be replaced by calculating the value of the dynamic viscosity coefficient of liquid steel using one equation. The results obtained support the use of the author’s rheological model for the above; however, this model still needs to be refined and extended to a wide range of alloying elements, mainly the extension of the carbon range.

Simultaneous Prediction of the Density and Viscosity of the Ternary System Water-Ethanol-Ethylene Glycol Using Support Vector Machine

Ethylene glycol is an organic solvent used in extractive distillation to separate water-ethanol mixtures. An appropriate process description requires accurate physical property data. In this paper, experimental liquid densities and dynamic viscosities of pure ethylene glycol as well as the ternary system water-ethanol-ethylene glycol are presented over a wide temperature range (298.15 to 328.15 K) at atmospheric pressure. Density and viscosity data of the ternary system of water-ethanol-ethylene glycol solutions were obtained from the literature and a support vector machine model was used to predict the density and viscosity of this system. The determination coefficients for density and viscosity of the ternary system of water-ethanol-ethylene glycol are 0.9854 and 0.9892, respectively. The mean square errors of density and viscosity are obtained 4.6572×10-4 and 3.4920×10-4, respectively. The results confirmed that the proposed method can predict the density and viscosity of the ternary system of water-ethanol-ethylene glycol as a function of temperature, using a support vector machine.

Simultaneous viscosity and density measurements and modeling of 2-alcohols at temperatures between (291 and 353) K and pressures up to 50 MPa

Dynamic viscosity (η) and density (ρ) were simultaneously measured for pure 2-alcohols (2-propanol, 2-butanol, 2-pentanol, 2-hexanol, and 2-heptanol) in the temperature range from (291–349) K and pressures up to 50 MPa. The measurements were performed using a new coil capillary viscometer coupled with a vibrating tube densimeter with a relative expanded uncertainty (coverage factor k=2) of 1.6% for the dynamic viscosity and 0.3% for the density considering the impurities of the compounds. The reliability of the equipment used was verified by determining and comparing the dynamic viscosity and density of ethanol with the data published in the international literature, resulting a maximum deviation of 10 μPa s for viscosity and 0.40 kg m−3 for density. Experimental dynamic viscosity and density data were successfully represented by two empirical models, obtaining good results in agreement with the uncertainty (maximum deviation of 1.3% and 0.15% for dynamic viscosity and density, respectively). From the experimental density data, the isothermal compressibility and isobaric thermal expansivity were determined.

Experimental and MD simulation investigation on thermophysical properties of binary/ternary mixtures of 1-butyl-3-methylimidazolium trifluoromethanesulfonate with molecular solvents

Ionic Liquids (ILs) show remarkable properties which make them environmental friendly. This work focused on sophisticated measurements of thermophysical properties of IL, 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([BMIM][CF3SO3]) with molecular solvents, dimethylsulfoxide (DMSO) and ethylene glycol (EG). The densities, ρ, speeds of sounds, u, and dynamic viscosities, η, of pure IL and its binary/ternary mixtures with DMSO or/and EG over the entire mole fractions range at various temperatures from 298.15 K to 323.15 K with an interval of 5 K and at pressure 0.1 MPa have been measured experimentally. Excess molar volumes, VE, excess molar isentropic compressions, ΚS, mE, viscosity deviations, ∆η, and Gibbs free energy of activations, ∆G⁎ have been evaluated from the experimental data at all the studied compositions and temperatures. The experimental studies of the focused systems reveal that the interaction found in IL + DMSO system is comparatively more pronounced as compared to IL + EG systems. But for DMSO + EG system, the interactions are strongest in contrast to IL-solvent systems. The VE, ΚS, mE and ∆η are fitted to Redlich-Kister polynomial equation and it fits well for all the studied systems. The experimental and derived parameters, varied with mole fraction and temperature, discussed in terms of ion-ion, ion-dipole and dipole-dipole interactions. Some semi-empirical models for the correlation of experimental dynamic viscosity data and to evaluate interactional parameters prevailing in the studied binary mixtures are also employed. The excess molar volumes of all the studied binary systems have been correlated with the Prigogine-Flory-Patterson (PFP) theory which shows good agreement with experimental one. The study of ternary system shows the strong interaction among the three components i.e., IL + DMSO + EG. The MD simulations studies have also been performed for pure components and their binary mixtures to determine the radial distribution function (RDF), the dynamic properties, mean square displacement (MSD), velocity auto-correlation function (vacf), Fourier transform and vibrational density of states (vDos) terms. The RDFs suggest that both the solvents, DMSO/EG substantially disrupt the long-range-anion-cation network characteristic of IL. Herein, DMSO shows their preference towards [BMIM]+ whereas, the EG towards [CF3SO3]− and it is attributed to the presence of H-bonding. The SDF studies reveal that [BMIM]+ has strong coordination sites for DMSO while, the EG shows weaker coordination.

A Nonequilibrium Model for Particle Networking/Jamming and Time-Dependent Dynamic Rheology of Filled Polymers.

We describe an approach for modeling the filler network formation kinetics of particle-reinforced rubbery polymers—commonly called filler flocculation—that was developed by employing parallels between deformation effects in jammed particle systems and the influence of temperature on glass-forming materials. Experimental dynamic viscosity results were obtained concerning the strain-induced particle network breakdown and subsequent time-dependent reformation behavior for uncross-linked elastomers reinforced with carbon black and silica nanoparticles. Using a relaxation time function that depends on both actual dynamic strain amplitude and fictive (structural) strain, the model effectively represented the experimental data for three different levels of dynamic strain down-jump with a single set of parameters. This fictive strain model for filler networking is analogous to the established Tool–Narayanaswamy–Moynihan model for structural relaxation (physical aging) of nonequilibrium glasses. Compared to carbon black, precipitated silica particles without silane surface modification exhibited a greater overall extent of filler networking and showed more self-limiting behavior in terms of network formation kinetics in filled ethylene-propylene-diene rubber (EPDM). The EPDM compounds with silica or carbon black filler were stable during the dynamic shearing and recovery experiments at 160 °C, whereas irreversible dynamic modulus increases were noted when the polymer matrix was styrene-butadiene rubber (SBR), presumably due to branching/cross-linking of SBR in the rheometer. Care must be taken when measuring and interpreting the time-dependent filler networking in unsaturated elastomers at high temperatures.

A Volumetric and Viscosity Study for the Binary Mixtures of Ammonium-Based Asymmetrical Gemini Ionic Liquids with Alcohols at T = 293.15–333.15 K

In this work, the experimental densities and dynamic viscosities of binary mixtures of ammonium-based room-temperature asymmetrical Gemini ionic liquids (GILs) 1-trimethylammonium-3-(pyridinium) propane bisdicyanamide ([N111C3Py][DCA]2) and 1-trimethylammonium-3-(1-methylpiperidinium) propane bisdicyanamide ([N111C3MPi][DCA]2) with methanol (MeOH) or ethanol (EtOH) over the entire concentration range were, respectively, determined experimentally at temperatures of (293.15, 303.15, 313.15, 323.15, and 333.15) K in the atmospheric pressure of 0.1 MPa. The excess molar volumes (VmE), excess dynamic viscosities (Δη), and excess Gibbs energy of activation (ΔG*E) of the mixtures were evaluated according to the experimental ρ and η values of pure [N111C3Py][DCA]2, [N111C3MPi][DCA]2, MeOH, EtOH, and their binary solutions at the investigated temperatures and pressure. The change of VmE and Δη were correlated with the Redlich–Kister-type expression and optimal fitting parameters were evaluated. It was observed tha...

Viscosity, Electrical Conductivity, Density and Surface Tension of Methyltriphenylphosphonium Carboxylate Ionic Liquids

Abstract In this paper, three new kinds of phosphonium-based room temperature ionic liquids (ILs) [Ph3PCH3][CH3(CH2)8COO] (MTPP-D), [Ph3PCH3][CH3(CH2)10COO] (MTPP-L), and [Ph3PCH3][CH3(CH2)12COO] (MTPP-M) were synthesized using triphenylphosphine, dimethyl carbonate and carboxylic acids as raw materials. The viscosity, electrical conductivity, density and surface tension of the synthesized ILs were measured in the temperature range from 298.15 K to 333.15 K under ambient pressure. Meanwhile, the effects of temperature and alkyl chain length on their viscosity, electrical conductivity, density and surface tension were also investigated. The molecular volume, standard entropy, lattice energy and isobaric expansivity of the three ILs were calculated at 298.15 K. Experimental results indicate that the viscosity, density and surface tension of the three ILs decrease significantly with the increase of temperature, while the electrical conductivity shows an opposite trend. The longer the alkyl chain, the higher the viscosity, the lower the electrical conductivity, density and surface tension of the ILs. The experimental dynamic viscosity can be well correlated by the Vogel-Fulcher-Tammann (VFT) equation and simple linear equation. The temperature dependence of electrical conductivity can be well fitted by Arrhenius equation and VFT equation. The molecular volume, standard entropy and isobaric expansivity increase with increasing alkyl chain length, while the lattice energy decreases.

Dynamic viscosity of colloidal silica suspensions at low and high volume fractions

A comprehensive study was carried out on the dynamic viscosity of X30 silica dispersions at both high and low volume fractions of colloidal silica particles at various electrolyte ionic strength and pH values. Booth and Ruiz-Reina and Carrique theoretical models (R-R&C) were compared in predicting the primary electroviscous effect (PEE) for viscosity at low volume fractions. To this respect the colloidal dispersion was well characterised with regards to electrolyte properties such as the Debye length, κ−1, calculated from the ionic strength, and zeta potential, ζ, calculated from the electrophoretic mobility using the full numerical model by O’Brien and White (O’B&W). R-R&C hard sphere model (which is a modified version of Simha hard sphere model that includes a boundary condition by Happel on the outer radius of the cell) and the semi-empirical Krieger-Dougherty (K-D) models were fitted to the experimental data at high volume fractions. At both low and high volume fractions the viscosity increased with pH and decreased with ionic strength. At low volume fractions both theoretical models significantly underestimated the experimental dynamic viscosities obtained in this work. This could be attributed to the fuzzy structures for silica particles in aqueous conditions reported previously in the literature, where a significantly larger electroviscous parameter, p, was obtained experimentally for silica particles. The experimental electroviscous parameter, pexp, in this work was found to be roughly an order of magnitude up to 26 times larger than that predicted by Booth and around 5 ± 1 times larger than the predicted p by R-R&C model allowing the introduction of a correction factor in the PEE coefficient obtained from R-R&C model enabling good prediction for X30 silica dispersions by the latter model. The significant improvement of the electroviscous effect predictions by R-R&C model compared to Booth model may be attributed to the limitations invalidating the Booth model at the electrolyte conditions in this study. At high volume fractions, the R-R&C hard sphere cell model, gave a much better fit to the experimental data compared to the K-D model, which also had the advantage of being only dependent on a coefficient that linearly relates an effective volume fraction postulated for the fuzzy silica particles to the experimental. The K-D model however, depends on the intrinsic viscosity, [η], which requires the calculation of the experimental slope of the dynamic viscosity against volume fraction in the dilute limit, and also on a maximum packing fraction as a fitting parameter. Due to the effect of the fuzzy structures on the viscosity, the latter effective volume fraction ϕeff was calculated using two approaches: (i) as a fitting parameter by fitting the R-R&C hard sphere model to the experimental viscosity data over the entire volume fraction range, and (ii) by fitting only the linear part of the experimental viscosity at low volume fractions, It is concluded that the R-R&C hard sphere model with the effective volume fraction accounting for the fuzzy structures fits reasonably well the full range of experimental results at low and high volume fractions. When the model was used with the Adamczyk effective volume fraction (i.e., considering only the dilute region in the fitting procedure), the predictions became worse at high volume fractions where significant deviations from the experimental results were found upon the increase of pH.

Proposing a novel and accurate model for forecasting dynamic viscosity of n-alkane in operational conditions

The viscosity of fluid is known as resistivity of fluid to flow and straightly affected by temperature and pressure. As it is obvious, the viscosity of reservoir fluid is known as one of the critical parameters which extensively effect on production. Therefore, in the present paper, multilayer perceptron artificial neural network (MLP-ANN) is used as a novel and accurate model to predict dynamic viscosity of normal alkanes in the operational conditions. To this end, 228 dynamic viscosity points as function of carbon number of n-alkane, temperature, and pressure were collected from a reliable paper. The comparison between MLP-ANN outputs and experimental dynamic viscosities is performed in graphical and statistical manners. The calculated coefficients of determination 0.99739 and 0.99051 for training and testing phases express the great ability of MLP-ANN algorithm in prediction of dynamic viscosity of n-alkane. According to the analysis, MLP-ANN has enough accuracy and potential to be used as software for which applicable in petroleum industry.

Viscosity calculation of 1‑ethyl‑3‑methyl‑imidazolium chloride ionic liquids based on three-body potential hydrogen bond model

In this study, we have developed an all-atom force field with three-body hydrogen bond model for 1‑ethyl‑3‑methyl‑imidazolium chloride ([Emim][Cl]), predicted the experimental dynamic viscosity successfully and calculated the relationship between dynamic properties and ion pair (IP) structures relaxation time. The partial atom charges and parameters of Lennard-Jones and hydrogen bond model are derived from ab initio molecular dynamic (AIMD) simulations. The strategy is that charges are fitted by AIMD structures and parameters are adjusted to make structure consistent between molecular dynamic (MD) and AIMD. The dynamic viscosities were calculated by Green-Kubo (GK) relation and were in excellent agreement with experiments results. Structure of ionic liquids was studied by using several distribution functions and IP time response was calculated. The calculated IP lifetime was found in linear correlation with viscosity and self-dynamic coefficient.

Effect of co-solvent and temperature on interactions in 1-ethyl-3-methylimidazolium trifluoromethanesulfonate + ethylene glycol or/and N,N-dimethylformamide, and ethylene glycol + N,N-dimethylformamide mixtures: Measurement of thermophysical properties

The excess molar volumes, VE, excess molar isentropic compressibilities, Κs,mE, viscosity deviations, Δη and Gibbs free energies of activation, ΔG∗ have been determined by using the experimentally measured values of densities, ρ, speeds of sound, u, and viscosities, η of pure 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][CF3SO3]), ethylene glycol (EG) and N,N-dimethylformamide (DMF) and of binary mixtures [EMIM][CF3SO3] + EG/DMF; EG + DMF in the mole fraction range (x1) from 0 to 1 and of ternary mixture [EMIM][CF3SO3] + DMF + EG in the range of x1 from 0.03 to 0.8 at temperatures, (298.15, 303.15, 308.15, 313.15, 318.15 and 323.15) K and pressure 0.1 MPa. The VE, Κs,mE and Δη values of binary systems have been correlated with Redlich-Kister polynomial equation. The VE, Κs, mE and Δη values of ternary system have been correlated with Cibulka equation. The variations of measured data with composition and temperature are discussed in terms of ion-ion, ion-dipole and dipole-dipole interactions prevailing in the mixtures. We have also applied a number of semiempirical relations for correlation/prediction of our experimental dynamic viscosity data and evaluated some interactional parameters of studied binary mixtures. The excess molar volumes of each binary system have also been correlated to the Prigogine-Flory-Patterson (PFP) theory.

A viscosity model for ionic liquids based on the Eyring's theory and a cubic EoS

A thermodynamic model based on the combined use of the Eyring's activated state theory and a cubic equation of state was developed here to accurately represent the dynamic viscosity of pure ionic liquids (ILs). Within the Eyring's theory, the net viscous flow of a pure IL is assumed to be governed by four main variables: (1) the energy necessary for a molecule to jump from an initial equilibrium position to a new one, (2) the energy necessary to break the molecular bonds to create a hole (vacant sites) of molecular size in the liquid, (3) the availability of the vacant sites, and (4) the frequency or the mean residence time of the jumping molecules. The various activation-state variables were then related to well-known thermodynamic potentials that in turn were estimated from two simple cubic equations of state of the van der Waals type (Soave or Peng-Robinson). The resulting model was successfully validated during the representation of experimental dynamic viscosities of three families of imidazolium-based ILs ([CXmim][BF4], [CXmim][PF6] and [CXmim][Tf2N]), four pyridinium-based ILs ([bmpy][BF4], [empy][EtSO4], [Et2Nic][EtSO4] and [hemmpy][Tf2N]) and two ammonium-based ILs ([cpmam][MeSO4] and [4bam][doc]) within a temperature range varying from 0 to 80 °C and at pressures from 1 up to 3000 bar thus covering a wide viscosity range of 10–19,610 mPa-s.

Viscosity Modeling of Ionic Liquids Using the Friction Theory and a Simple Cubic Equation of State

In the present work, the well-known friction theory (FT) based on friction concepts of classical mechanics and the van der Waals theory of fluids has been modified to accurately represent the dynamic viscosity of pure ionic liquids in a rather simplified manner. Unlike previous FT applications to pure ionic liquids, the dilute gas limit for viscosity was excluded from the present model since it is negligible for ionic liquids which exhibit extremely low vapor pressures; the friction term thus prevailed for viscosity calculations. The latter was expressed in terms of new temperature-dependent friction coefficients whereas the repulsive and attractive pressure terms were in turn estimated from two simple cubic equations of state (Soave or Peng–Robinson) rather than using sophisticated multiparameter equations of state such as SAFT- or CPA-based expressions previously used by other authors. The resulting model was successfully validated during the representation of experimental dynamic viscosities of three f...

Excess Molar Volumes, Excess Molar Isentropic Compressibilities, Viscosity Deviations, and Activation Parameters for 1-Ethyl-3-methyl-imidazolium Trifluoro-methanesulfonate + Dimethyl Sulfoxide and/or Acetonitrile at T = 298.15 to 323.15 K and P = 0.1 MPa

The densities, ρ, speeds of sound, u, and dynamic viscosities, η, of pure 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, ([EMIM][CF3SO3]), dimethyl sulfoxide, (DMSO), acetonitrile, (ACN), and their binary and ternary mixtures have been measured experimentally over the entire composition range and at temperatures of 298.15, 303.15, 308.15, 313.15, 318.15, and 323.15 K and at a pressure of 0.1 MPa. The excess molar volume, VE, excess molar isentropic compressibility, Ks,mE, viscosity deviations, Δη, Gibbs energy of activation, ΔG*, and excess Gibbs energy of activation, ΔG*E have been calculated using the experimental ρ, u, and η values of pure [EMIM][CF3SO3], DMSO, ACN, and their binary/ternary mixtures at the studied temperatures and pressure. The excess/deviations properties for the studied binary/ternary systems have been fitted to Redlich–Kister equation. The variations of these parameters with composition and temperature are discussed in terms of ion–ion, ion–dipole, and dipole–dipole interactions prevailing in these mixtures. The excess molar volumes of each binary system have also been correlated to the Prigogine–Flory–Patterson (PFP) theory. Some semiempirical models for correlation/prediction of experimental dynamic viscosity data for studied binary and VE, Ks,mE, Δη, and ΔG*E for ternary mixtures have been applied.