Van Laar Equation Research Articles

Solubility and thermodynamic parameters of nicotinic acid in different solvents

Nicotinic acid is an important compound needed for the body to keep proper functioning and stay healthy. The determination of solubility parameters in different solvents can be useful for operations such as crystallization or encapsulation of nicotinic acid. In this study, we critically evaluated the solubility of nicotinic acid in nine solvents: water, methanol, ethanol, propanol, propan-2ol, butanol, acetone, ethyl acetone and dimethyl sulfoxide (DMSO). Solubility data are provided as mole fractions of solvent versus temperature. Results showed that DMSO afforded the highest nicotinic acid solubility, greater than the ideal solubility values. Thermodynamic parameters such as the activity coefficient, melting temperature and enthalpy of fusion were determined by differential scanning calorimetry. Non-predictive activity coefficient models were obtained to represent the experimental data through Margules, van Laar, Wilson, NRTL, and UNIQUAC equations. The van Laar, Wilson, and NRTL models showed broadly similar performance. The UNIQUAC model showed an optimum performance for six of the nine solvents.

Thermal, optical, and volumetric studies on mixing properties of binary nematic mixtures of 9CHBT/11CHBT

• Phase diagrams of a series of binary nematic mixtures (9CHBT/11CHBT) were studied by DSC method. • The modified four-parameter model was used by fitting the experimental data. • The temperature dependence of refractive indices, birefringence and order parameters in nematic phase was investigated. • Quantum chemical calculations on the nematogens provide supportive picture of the optical measurements. Phase diagrams and optical properties of a series of nematic binary mixtures composed of 4-(trans-4′-n-nonylcyclohexyl) isothiocyanatobenzen (9CHBT) and 4-(trans-4′-n-undecylcyclohexyl) isothiocyanatobenzen (11CHBT) were established in the entire range of molar fraction by differential scanning calorimetry method, refractometry as well as density measurements. In this research the thermodynamic, optical, and volumetric properties of the eutectic mixture ( E 9 , 11 ) composed of 9CHBT and 11CHBT ( x 11 C H B T = 0.4 ) were studied and interpreted. The binary phase diagram is in comparable with that predicted from Schroder–van Laar equation. The excess functions were determined using the calculated activity coefficients of the eutectic mixture. Moreover, the temperature dependence of refractive indices, birefringence, and order parameters of the pure nematogens and the binary eutectic mixture was investigated. In contrast to the individual nematogens, the eutectic mixture ( E 9 , 11 ) displays a crossover temperature ( T CO ) based on the four-parameter model. Finally, results from quantum chemical calculations on the studied nematogens provide an overall supportive and coherent picture of the thermal, optical measurements. All calculations were performed using the Turbomole software package. The used methodology allows for an acceptable approximation of effective polarizabilities.

Activity coefficient models for accurate prediction of adsorption azeotropes

In this study seven adsorption azeotropes involving binary systems and zeolite-based adsorbents were systematically investigated. Pure component isotherms and mixed-gas adsorption data were taken from published literature except for the benzene–propene system on silicalite, which is newly presented in this work using molecular simulations. Experimental adsorbed phase composition and total amount adsorbed of the azeotropic systems were compared with the predictions of several models including: the ideal adsorbed solution theory (IAST), the heterogeneous ideal adsorbed solution theory (HIAST) and the real adsorbed solution theory (RAST) coupled with the 1-parameter Margules (1-Margules) and the van Laar equations. In the latter two models an additional loading parameter was incorporated in the expression of the excess Gibbs energy to account for the reduced grand potential dependency of the activity coefficients in the adsorbed phase. It was found that the HIAST and RAST–1-Margules models were able to predict the azeotropic behaviour of some systems with good accuracy. However, only the RAST–van Laar model consistently showed an average relative deviation below 3% compared to experimental data for both the adsorbed phase composition and the total amount adsorbed across the systems. This modified van Laar equation is therefore preferable in those engineering applications when the location of adsorption azeotropes is required with great accuracy and when there is lack of detailed characterization of the adsorbent that is needed to carry out molecular simulations.

Effect of combining rules on modeling of asphaltene precipitation

Asphaltene deposition causes serious problems in the oil industry and reduces oil recovery. Deposition happens as a consequence of asphaltene precipitation which is a process as a result of a change in thermodynamic stability. Thus, prediction and preventing of the precipitation condition are the first step of preventing asphaltene precipitation and deposition. In this study, a thermodynamic model for asphaltene precipitation has been developed using Peng–Robinson (PR), Soave–Redlich–Kwong (SRK), and a new modification on SRK [modified-SRK equations of state (EOS)]. To modify EOS for non-pure sample (oil sample), van der Waals mixing rule with three types of combining rule containing conventional, Margules, and van Laar type was used. In addition, to verify the derived model, the experiments were conducted on a live oil sample to investigate the effect of pressure reduction and gas injection [nitrogen (0.1, 0.2, and 0.4 mol fraction) and first stage gas (0.2, 0.4 and 0.6 mol fraction)] on asphaltene precipitation. The results show that at low pressures (pressures below 5000 psia), nitrogen is not soluble in oil and the injection of nitrogen reduces asphaltene precipitation because of the liberation of the light component from crude oil; however, increasing the pressure (pressures above 6000 psia) increases the solubility of nitrogen and increases the asphaltene precipitation. For the first stage gas injection, asphaltene precipitation increases because of its high solubility in crude oil at any pressure. The amount of asphaltene precipitation due to first stage gas injection is higher than nitrogen injection except at nitrogen concentration and pressures near the bubble point (pressure of 7000 psia and nitrogen injection of 0.1 mol fraction). According to the modeling results, van Laar type combining rule in conjugated with modified-SRK-EOS predicts the amount of asphaltene precipitation very well at all situations of pressures and different gas injections, and has the least deviation from experimental data rather than the other two types of combining rules; and using mentioned combining formula, the RMSE value decreases to about 50% of the conventional combining rule. It is because of the accurate and distinct interaction parameters of each pair of components in van Laar equation.

Influence of Gas and Oil State on Oil Mobility and Sweet-Spot Distribution in Tight Oil Reservoirs from the Perspective of Capillary Force

Summary The coexisting free gas, solution gas, and oil in a tight oil reservoir, constrained by the capillary force of the micrometer/nanometer pore/pore-throat system, are of crucial importance to the sweet spot of a tight oil reservoir. Equations of modified total capillary force for the liquid phase are proposed to indicate the tight oil mobility in situ, and are derived from the Kelvin capillary force equation, the Peng-Robinson (PR) equation of state (EOS) (Robinson et al. 1977), and the Van-Laar (VL) equation (Renon and Prausnitz 1968). In addition, relationships between the vapor/liquid state, phase-flow state for production, and gas/oil ratio (GOR) are established in correspondence with the production data of North American and Chinese (Yanchang) tight oil plays. The following conclusions can be drawn. We proposed a modified total capillary force function to indicate the tight oil mobility in situ, using the PR EOS method and the EOS+λ (VL equation) method. We identified five phase stages according to the gas volume ratio ( yi) in situ: the single-phase oil flow stage, the multiphase transient-flow stage, the multiphase stable-flow stage, the multiphase supercritical-flow stage, and the single-phase gas flow stage. Tight oils are more mobile in three stages: near the critical point of yi-critical(1), such as in the Yanchang and Bakken tight oils; at the transition zone between oil and wet-gas zones before yi-critical(2), such as in the Eagle Ford tight oil; and between the yi-critical(2) and yi-critical(3) in a gas-condensate state, which is at the transition zone between wet-gas and dry-gas zones.

Visco-elastic properties of multi-component mixtures of hockey stick-shaped liquid crystal compounds

Measurements of optical birefringence (Δn), permittivity (ε||, ε⊥), splay elastic modulus (K11) and rotational viscosity (γ1) have been carried out on the nematic (N) phase of a few multi-component liquid crystal mixtures having the hockey stick-shaped 4-(3-n-alkyloxy-2-methyl-phenyliminomethyl)phenyl 4-n-alkyloxycinnamate compounds. Three eutectic mixtures (tri-, tetra- and penta-component) were prepared using the Le Chatelier, Schröder and Van Laar (CSL) equation. The nematic range in all the investigated mixtures has been found to be relatively greater than that in most of the pure components. The Δn values have been found to be comparatively smaller than those for the constituent compounds. A temperature dependent inversion in the static dielectric anisotropy (Δε = ε|| − ε⊥) has been observed for all the mixtures on entering the anticlinic smectic-C (Sm-Ca) phase. No trace of pretransitional divergence has been detected in the temperature dependence of K11 in vicinity of the nematic to lower smectic-C transition. At a fixed reduced temperature, the γ1 values are either slightly higher or close to those of the pure compounds. The outcomes are explained in the framework of influence of molecular structure on the phase behaviour of multi-component mesogenic system.

Investigation of molecular interactions & prediction of calorimetric potentials of a binary liquid system at T = 308.15 K: An insight from physicochemical parameters

Excess values of surface tension/isothermal compressibility/internal pressure/free volume/enthalpy/entropy and Gibbs energy are computed using the experimentally measured density (ρ) and ultrasonic speed (u) for the binary liquid mixtures of dimethyl sulphoxide with acetophenone at T = 308.15 K. Activity coefficients and excess chemical potential are estimated using Morgules, Porter, Van laar and Wilson equations. The studied system shows departure to the ideality indicating the presence of weak interactions. Further, PFP theory is tested to correlative the experimental excess molar enthalpy. Moreover, PFP theory is extended to compute different derivatives of thermodynamic potentials rather calorimetric measurements. The present investigation also encompass of assessment of the acoustic non-linearity parameter (B/A) along with computation of cohesive energy, ΔA, Van der Wall's constants (a,b), distance of closest approach (d).

밀폐식 장치를 사용한 Water+1-Propanol 과 Water+2-Propanol의 인화점 측정과 계산

인화점은 가연성 액체 용액을 안전하게 취급하기 위한 중요한 성질 중 하나이다. 본 논문에서는 Seta flash 밀폐식 장치를 이용하여 이성분계 용액인 water+1-propanol과 water+2-propanol계의 인화점을 측정하였다. 회귀 분석법을 이용하여 인화점을 계산하였다. 또한 라울의 법칙을 이용하여 인화점을 계산하였고, van Laar 식의 이성분계 파라미터를 최적화시키는 방법을 통해 인화점을 예측하였다. 각 인화점 계산 결과와 측정 결과를 비교하였다. 그 결과, 회귀 분석법에 의한 인화점 계산치가 가장 측정치를 잘 모사하였다. Flash point is the one of the important properties for the safe handling of inflammable liquid solution. In this paper, flash points of binary liquid solutions, water+1-propanol and water+2-propanol, were been measured by using Seta flash closed cup aparatus. Flash point was estimated using regression analysis method. Flash points were also estimated by the method based on Raoul's law and the method optimizing the binary parameters of van Laar equation. Experimental results were compared with the calculated results. The regression analysis method is able to estimate the flash point fairly well for water+1-propanol and water+2-propanol mixture.

Predicting The Liquid Phase Equilibrium of Multi-Components Extraction By Thermodynamic Models

Extraction of multi-component is commonly used in the industry. To design new equipment or to stimulate the performance of existing units, the liquid-liquid equilibrium data are very useful. The multi-component system equilibrium, therefore, can be estimated based on the parameters of a single-component system with correlations in estimating thermodynamic in liquid-liquid phase equilibrium with the Wohl, Van Laar, and Three-Suffix Margules equations. Thermodynamic models for the extraction of phenolic compounds using an aqueous acetone and an aqueous methanol solvents showed that the Three-Suffix Margules’s model is more suitable for predicting the liquid equilibrium in multi-component extraction compared to the Wohl’s, and Van Laar’s. The activity coefficients of methanol, acetone, phenol, o-Cresol, and p-Cresol in the extract phase and raffinate phase are really higher than unity. It means that they are far from ideal condition. The activity coefficients of water and kerosene in their phases are close to one. It means that they are nearly ideal in their phases.

Comparative Method of Calculating the Thermodynamic Parameters of Some Uranium Hexafluoride Solutions

It is shown that the thermodynamics characteristics of uranium hexafl uoride solutions with volatile hexaand pentafl uoride elements are a consequence of the strictly symmetric confi guration of their molecular structure in the gaseous and liquid states. Simple methods are proposed for evaluating the properties of binary mixtures of elemental penta- and hexafl uorides. These methods are based on a comparison of the element–fl uorine bond length in the constituent molecules of system and the known enthalpy of mixing of one solution with the potential energy in the formation of a pair of unlike molecules of a different solution. Researchers looking for a universal method of deep purifi cation of uranium hexafl uoride have turned their attention to a rectifi cation method, for which there are no limitations on the depth of purifi cation, and a list of impurities to be removed, including metal impurities which are diffi cult to remove by means of water-extraction conversions of uranium concentrates and give volatile fl uorides (molybdenum, tungsten, ruthenium, technetium, and others). Moreover, its specifi c productivity is high, the energy consumption is low, and the separation effi ciency is high. These advantages are due to the special properties of uranium hexafl uoride as a working substance for rectifi cation: high density of liquid (more than 3.5 times higher than the density of water) and gaseous uranium hexafl uoride, low viscosity comparable to that of water, good wettability of the metals which are corrosion resistant to fl uoride media, and low heat of evaporation of liquid uranium hexafl uoride (less than 1/10th that of water). Deep purifi cation of uranium hexafl uoride raw material by rectifi cation has been used in the Republic of South Africa for several decades now [1]. In our country, we have experience in prolonged operation of a large-tonnage rectifi cation process for purifying sublimate and high-enrichment uranium hexafl uoride [2–4]. In order to develop a rectifi cation process, it is necessary to have information on the phase equilibrium of mixtures based on uranium hexafl uoride and to predict the properties of systems with which it is diffi cult to experiment. Computer methods of calculating steam-water systems have now been developed and are being improved; examples are models of local compositions Wilson, NRTL, UNIQUAC, equations of state SRK, Peng Robinson, and the group model UNIFAC, TTA [5–7]. They are based on the equation of thermodynamic equilibrium between coexisting phases and are generalizations of the Van-der-Waals equation of phase equilibrium, expressed in terms of partial properties [8]. Some forms of this equation are identical to a previously used van-Laar equation expressing the dependence of the coeffi cient of activity of a component on the composition of the solution [9]. Such methods of calculating the liquid–vapor equilibrium in nonideal systems take account of the effect of variable temperature and are convenient for modeling mixtures with an appreciable difference of the boiling temperature of pure components, making it possible to obtain good agreement between the computed and experimental parameters for some solutions. The application of a comparative method for calculating the properties of pure substances and solutions and the characteristics of phase and chemical equilibria is illustrated in the monograph [10]. In the present work, a method is proposed for fi nding parameters that can be used to calculate the vapor–liquid equilibria of mixtures of elemental hexa- and pentafl uorides by means of a comparative method.

Limiting activity coefficient measurements in binary mixtures of dichloromethane and 1-alkanols (C1–C4)

Limiting activity coefficients γ∞ in binary mixtures of dichloromethane with four lower 1-alkanols (C1–C4) were experimentally determined employing alternatively the techniques of inert gas stripping, comparative ebulliometry, Rayleigh distillation, and differential distillation. For each case, the suitable technique was chosen on the basis of the limiting relative volatility of the solute and/or volatility of the solvent. The measurements yielding data of good accuracy (relative standard uncertainty of γ∞ from 0.01 to 0.03) were carried out at several temperatures in the range from (283–333) K. The variation of limiting activity coefficients with temperature was fitted by a suitable two- or three-parameter equation and compared with available literature information on both limiting activity coefficients and calorimetric partial molar excess enthalpies at infinite dilution. The performance of the leading prediction method Modified UNIFAC was further examined using these new data. Concentration dependences of activity coefficients calculated from their infinite dilution values using van Laar equation were found to agree well with those inferred from reliable VLE data from the literature. The occurrence of an azeotropic point was tested for the systems under study and the temperature dependence of the azeotropic composition was estimated for mixtures of dichloromethane with methanol and ethanol.

Solubility Measurement and Correlation of Isobutane with Two Pentaerythritol Tetraalkyl Esters between (293.15 and 348.15) K

The solubilities of isobutane (R600a) in pentaerythritol tetrapentanoate (PEC5) and in pentaerythritol tetraheptanoate (PEC7) between (293.15 and 348.15) K have been measured based on the isochoric saturation method. The experimental solubility data were correlated by using the Peng–Robinson equation of state with the LCVM mixing rule in which the excess Gibbs energy at infinite pressure was represented by the van Laar equation. The absolute average deviation and maximum absolute deviation of the pressure from the correlated results was 1.18 % and 3.27 % for R600a + PEC5 system, respectively. For the R600a + PEC7 system, the absolute average deviation and maximum absolute deviation of pressure was 0.92 % and 2.17 %.

Seta-flash 밀폐식 방법에 의한 n-hexanol+n-butyric acid 계와 n-butanol+propionic acid 계의 인화점 측정

The flash point is one of the most important physical properties used to determine the fire hazard of flammable liquid mixture and defined as the lowest temperature at which a liquid produces sufficient vapor to form a combustible mixture with air. The main purpose of this paper is to measure and predict the flash point of binary flammable miscible mixtures. The flash points for n-hexanol+n-butyric acid and n-butanol+propionic acid, were measured by using Seta-flash closed cup method. The experimentally derived data were correlated with the binary interaction parameters of the van Laar and NRTL equations through the optimization method. The flash points estimated by these correlations were compared with those calculated by the method based on Raoult`s law. The optimization method were found to be better than the method based on the Raoult`s law.

A novel polynary fatty acid/sludge ceramsite composite phase change materials and its applications in building energy conservation

The preparation and characteristics of a composite phase change material (PCM) produced by incorporating polynary fatty acid eutectic mixture into sludge ceramsite were studied. According to Schröeder–Van Laar equation, five different kinds of polynary fatty acid eutectic mixture were prepared, and one of them, suitable for regulating room temperature, was absorbed into sludge ceramsite by vacuum impregnation method. The microstructures were observed by scanning electron microscope (SEM). The thermal properties and chemical structures were analyzed by differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectrometer, respectively. The durability or stability of the composite PCM was determined by heating–cooling cycles test, and the temperature regulation effect was tested by building models. The results indicated that polynary fatty acid eutectic mixture can be retained by 46 wt.% into the pores of sludge ceramsite without seepage. The melting temperature of composite PCM was 26.66 °C, and the corresponding melting enthalpy was 47.1 J/g, suitable to regulate building room temperature. The preparation of composite PCM was just a physical combination, and its chemical structures can remain stable in application process. In addition, model experiments showed that the prepared composite PCM can significantly reduce indoor temperature fluctuation, suitable for building energy conservation.

A new approach to study interaction parameters in cyanobiphenyl liquid crystal binary systems

The phase transition of heptylcyanobiphenyl 7CB and pentylcyanobiphenyl 5CB liquid crystals was investigated using the differential scanning calorimetry DSC technique. Then, the phase transition of different compositions of 7CB/5CB binary mixture was studied to determine the eutectic point. The phase diagram of mentioned binary system in 7CB mole fraction of 0.45 at T=273.45K is in good agreement with that of predicted from Schroder–van Laar equation. The thermodynamic excess functions and interaction parameters were calculated to describe the phase transition physically using the non-random mixing for the first time. The P∗ randomicity parameter was used to describe the phase transitions of C–N and N–I in which a small amount of P∗ shows a non-random identity of C–N phase transition. Contrarily, the P∗ is greater in N–I phase transition showing a random mixing process.

Separation and Solubility of Cis and Trans Isomers in Nanostructured Double-Decker Silsequioxanes

A fractional crystallization method was used to separate the cis and trans isomers of three double-decker silsesquioxanes (DDSQs) with an aminophenyl moiety in a THF + hexanes solvent mixture. The experimental solubilities were fitted to the Schroder–van Laar equation with activity coefficients determined using the NRTL model by adjusting the binary interaction parameters. The ability to separate these cis and trans isomers was affected by the regioisomer (m- or p-aminophenyl) and the R moiety (cyclohexyl or methyl) coupled via silicon. For a given DDSQ compound, the variances between the solubilities of the cis and trans isomers depend on differences in thermal properties (Schroder–van Laar). Cis isomers were 33 times more soluble than trans isomers for p-aminophenyl (R = methyl) and 22 times more soluble for the analogous m-aminophenyl in a solution of THF and hexanes. For a more sterically hindered m-aminophenyl (R = cyclohexyl), the cis isomers were only 3.5 times more soluble, and the overall solubil...

The singular points and phase diagram of the supercritical region of a substance

This paper suggests using the supercritical point and the maximum fluctuation point on the supercritical isotherm for the analysis of the behavior of various substances in the vicinity of the critical point. These three points lie at the vertices of a triangle that is formed by the supercritical isotherm, the line of the local minima of stability, and the line of maxima of fluctuations. In this triangle, which is called supercritical, the fluctuations and instability behave such that this part of the phase surface is most interesting from the viewpoint of performing various chemical reactions. Here, large fluctuations and the stability of the system rapidly decrease with increasing volume. This region is studied in the approximation of the van der Waals and Van Laar equations.

Cleveland 개방식 장치를 이용한 Acetic acid+Formic acid 계의 인화점 측정과 예측

인화점은 공기와 섞인 가연성 증기의 농도가 발화하기에 충분할 때의 최저 온도로, 가연성 액체 용액의 화재 및 폭발 위험성을 분석하는데 사용되는 주된 물리적 특성치이다. 단일 성분의 인화점 정보는 여러 문헌에서 얻을 수 있으나, 가연성 이성분계 혼합물의 인화점은 충분히 제공되어 있지 않다. 본 연구의 목적은 이성분계 가연성 액체 혼합물인 아세트산-포름산계의 인화점을 측정하고, 산출하는 것이다. 인화점 측정은 Cleveland 개방식 장치를 사용하였고, 실험값은 van Laar 식과 Wilson 식을 활용한 최적화 기법에 의해 산출된 값과 비교하였다. 그리고 라울의 법칙에 의해 산출된 값과 비교되었다. 그 결과, 최적화 기법에 의한 산출값이 Rauolt의 법칙에 의한 산출값보다 실험값에 보다 근접하였다. The flash point is the lowest temperature at which there is enough concentration of flammable vapor to form an ignitable mixture with air. The flash point is a major physical property used to analyse the fire and explosion hazards of a flammable liquid solution. The flash point data for pure components are easily available in several literature. But the flash points of the flammable binary solutions appear to be scarce in the literature. The objective of this study is to measure and estimate the flash point of acetic acid-formic acid system. Cleveland open cup tester was used to measure the flash point. The experimental data were compared with the values estimated by the Raoult's law and the optimization methods based on van Laar and Wilson equations. As a result, the estmated values by optimization methods were found to be better than those based on the Raoult's law.

이성분계 용액의 최대인화점 현상의 측정과 예측

인화점은 액체 용액의 폭발과 화재의 위험성을 특징짓는 가장 중요한 물성치 중 하나이다. 액체 혼합물의 최대인화점은 용액을 구성하는 개별 성분들의 인화점보다 높은 것을 의미한다. 본 연구에서는 2-pentanol+acetic acid 계의 인화점을 Seta flash 밀폐식 장치를 통해 측정하였다. 이 계는 최대인화점 현상을 나타내었다. 또한 인화점은 Raoult의 법칙을 이용하여 예측하였고, van Laar 식과 Wilson 식을 활용한 최적화 기법에 의해서도 예측하였다. 최적화 기법에 의한 예측 방법이 Rauolt의 법칙에 의한 예측 방법 보다 측정치를 잘 모사하였다. The flash point is one of the most important physical properties to charaterize fire and explosion hazard of liquid solutions. The maximum flash point of liquid mixture is larger than those of the individual components. In this study, the flash points of 2-pentanol+acetic acid system were measured by Seta flash closed cup tester. This system exhibited the maximum flash point behavior. The flash points were estimated by the Raoult's law and the optimization methods using the van Laar and Wilson equations. The calculated values by optimization methods were found to be better than those based on the Raoult's law.

Volumetric Properties of the {x 1[C4mim][MeSO4] + (1 − x 1)MeOH} System at Temperatures from (283.15 to 333.15) K and Pressures from (0.1 to 35) MPa

Densities of pure 1-butyl-3-methylimidazolium methylsulfate, [C4mim][MeSO4], and its mixtures with methanol have been measured. Measurements were made with an accuracy of ±0.2 kg·m−3, using a vibrating-tube densimeter, over the temperature and pressure ranges (283.15–333.15) K and (0.1–35) MPa, respectively. The experimental densities for the pure ionic liquid and alcohol have been correlated by the Tait equation. The results for the {x 1[C4mim][MeSO4] + (1 − x 1)MeOH} system have been correlated by a van Laar equation involving parameters that are dependent on temperature and pressure. Excess volumes have been obtained directly from the experimental densities, while isobaric expansivities, isothermal compressibilities, and related excess properties were calculated from the correlation equation. Exceptionally strong pressure and temperature influences on these properties were observed.Electronic supplementary materialThe online version of this article (doi:10.1007/s10953-013-0016-8) contains supplementary material, which is available to authorized users.