Kinds Of Mixtures Research Articles

Thermodynamic properties of 1,1,1,2-tetrafluoroethane + polyether mixtures up to 60 MPa

In this work we report several derived thermodynamic properties, the isothermal compressibility (κT), the isobaric thermal expansion coefficient (αp), and the internal pressure (π), and their excess functions (κTE, αpE, and πE) for the refrigerant + lubricant mixtures HFC-134a + triethylene glycol dimethyl ether and HFC-134a + tetraethylene glycol dimethyl ether. These properties have been determined in wide temperature (293.15–373.15 K) and pressure (10–60 MPa) ranges in an effort to better understand the behaviour of these kinds of mixtures and their thermophysical properties as functions of temperature, pressure, and composition. The analysis of the thermodynamic excess properties (negative values for κTE and αpE, positive values for πE) for both systems shows a high degree of interaction between the refrigerant and the synthetic lubricant molecules. Key words: HFC-134a, high pressure, internal pressure, isobaric thermal expansion coefficient, isothermal compressibility, polyglycol ethers, refrigerant–lubricant mixtures.

Rutting response of hot-mix asphalt to generalized dynamic shear moduli of asphalt binder

In this paper, a stiffness indicator of Generalized Dynamic Shear Modulus (GDSM) of asphalt binders is introduced to study the rutting resistance of unmodified and polymer-modified asphalt binders. Seven binders of two unmodified and five SBS-modified binders are tested. At 60 °C, the data of peak shear stress and corresponding peak shear strain are obtained for each binder by the Dynamic Shear Rheometer (DSR). In the linear viscoelastic region of binders, the GDSM is calculated on the basis of the constitutive shear stress–strain equation that is obtained by fitting the Box–Lucas model to experimental data. Two kinds of bituminous mixtures classified by the type of aggregate gradation are used to evaluate the rutting potential. For each gradation, the aggregate is blended with the seven binders. For each mixture, single binder content is employed so that differences in rutting depth can be investigated, depending on various GDMS values of the binders. The rutting depth of mixes is tested with the Asphalt Pavement Analyzer (APA) at 60 °C and the correlation between the average rutting depth and the GDSM is established. Results indicate that for two kinds of mixtures, there exists a good correlation between the GDSM and the average rutting depth. It is confirmed that GDSM is useful as a stiffness indicator for the evaluation of rutting resistance of binders. The constitutive equation of shear stress–strain can be obtained by fitting the Box–Lucas model up to the peak shear stress, which represents an explicit mechanistic implication.

Prediction of Compressive Strength of In-Situ Concrete Based on Mixture Proportions

This paper presents the regression equation for predicting compressive strength of in-situ concrete. For this purpose, this study used the data of mixture proportions of ready-mixed concrete and test results of compressive strength at construction sites.This study used 1442 compressive strength test results obtained from the specimens having 59 different kinds of mixtures with specified compressive strength of 18~27MPa, water-cement ratio of 0.39~0.62, maximum aggregate size of 25mm, and slump of 12~15cm.Principal factors that influence compressive strength of concrete are selected by a correlation analysis, and then the multiple linear regression analysis is carried out for predicting compressive strength according to water-cement ratio or cement-water ratio, cement contents and cement-aggregate ratio.

‘Mirror model’ gives separation of convolutive mixing of PNL mixtures

The proof is given that the so called 'mirror model' as demixing model is able to recover original sources after non-trivial mixing. The issue explored is the capability to separate sources, in a blind way, after the convolutive mixing of post nonlinear (PNL) mixtures. The strictness of that kind of mixture produces non-trivial problems in separating signals without any adequate assumption on recovering architecture.

Thermophysical properties of four binary dimethyl carbonate + 1-alcohol systems at 288.15–313.15 K

Densities and kinematic viscosities for the dimethyl carbonate (DMC) + (ethanol, 1-propanol, 1-pentanol, 1-octanol) binary systems have been experimentally determined at 288.15, 293.15, 303.15 and 313.15 K and normal atmospheric pressure, over the entire mole fraction range. Moreover, the excess molar enthalpies for the present binary mixtures were determined at 303.15 K. Other mixing properties of interest such as the excess molar volumes, the viscosity deviations, the isobaric thermal expansion coefficients, the excess expansibilities, and the pressure coefficients of the molar excess enthalpy have been also obtained for each of the systems and temperatures. The obtained properties have been compared with those reported by other authors when available in the literature, and have been analyzed in terms of the molecular interactions present in this kind of mixtures. The composition–viscosity data were correlated with several specific equations to evaluate their feasibility for these systems.

VISCOSITY PREDICTION OF CARBON DIOXIDE + HYDROCARBON MIXTURES USING THE FRICTION THEORY

ABSTRACT The general one-parameter f-theory model has been used in conjunction with the SRK and the PR EOS to predict the viscosity of well-defined carbon dioxide + hydrocarbon mixtures. The predicted viscosities are within the uncertainty appropriate for most industrial applications. Although the studied mixtures are simple representations of real oil mixtures with carbon dioxide, the f-theory approach can easily be extended to more complex scenarios, such as the simulation of carbon dioxide enhance oil recovery. Additionally, a comparison with the LBC model, which is a widely used model in the oil industry, has been carried out. In contrast to the f-theory models, the strong dependency that the LBC model has on the accuracy of the density is clearly evident for the kind of mixtures studied in this work. Furthermore, it is shown how the phase behavior complexity that carbon dioxide + hydrocarbon mixtures develop may have a direct influence on the performance of the viscosity modeling and prediction.

Excess properties for acetophenone + butanols at 298.15 K

Densities, viscosities, and refractive indexes of binary systems acetophenone + n-butanol, + sec-butanol, and + 2-methyl-1-propanol have been measured at 298.15 K and atmospheric pressure, over the whole composition range. The excess values of molar volume, viscosity, Gibbs free energy of activation of viscous flow, and internal pressure were calculated from experimental measurements. Based on the variations of the excess functions with composition, conclusions about the molecular interactions in these kinds of mixtures were obtained.Key words: excess properties, binary mixtures, butanols, acetophenone.

Townsend ionization coefficients of some argon-based mixtures in strong nonuniform electric fields

The reduced Townsend ionization coefficient α/P is derived from the measurement of the mean gas amplification factor in a low-pressure (P ⩽ 50 kPa) proportional counter filled with argon–propane and argon–(dimethyl-ether) mixtures of various concentrations. The results are compared with our previous α/P values for argon–isobutane mixtures [I. Krajcar Bronić and B. Grosswendt, Nucl. Instrum. Methods Phys. Res. B 142, 219 (1998)]. The range of the reduced electric field strengths was 7×104 V m−1 kPa−1⩽Sa⩽4×106 V m−1 kPa−1. In such strong electric fields electrons do not reach the equilibrium with the electric field and the reduced gas gain depends on the gas pressure. For the analysis of the experimental gas gain data we used the field gradient model of Townsend–Williams–Sara–Segur. We determined the pressure dependent coefficients A* and B* of the Townsend ionization coefficient α/P=A*×exp(−B*/Sa). We found that the coefficients increase (i) if the admixture concentration increases at constant pressure, and (ii) if the pressure decreases at constant admixture concentration. In both cases the coefficients increase with the increase of Sa. The effective ionization potential of the mixtures, Vi*=B*/A*, at low admixture concentrations reaches the ionization potential I of the admixture as a consequence of the transfer of energy from the excited metastable states of argon to ionization of the admixture through the Penning effect. When α/P vs Sa curves for mixtures of different concentrations at constant total pressure are compared, crossings of the α/P curves at a certain range of Sa values are observed in all kinds of mixtures and for all pressures. We show the necessity of the crossings by taking into account the mathematical properties of the function describing the ionization coefficient.

On the role of the definition of potential models in Gibbs ensemble phase equilibria simulations of the H2S-pentane mixture

The effect of treating explicitly the coulombic and polarization interactions is investigated through the calculation of the coexistence curve of the pentane-H2S binary mixture. In this work, potential models have been developed for hydrogen sulphide and pentane, which include electrostatic sites—estimated from ab initio calculations—and polarizable sites—estimated from experimental data—in addition to Lennard-Jones sites. Compared to existing models, these new models have the same number of fitting parameters to experimental thermodynamic data. They are shown to correctly describe the coexistence curve of the pure compounds. When applied to the case of mixtures, together with Lorentz-Berthelot combining rules, they allow one to obtain a more accurate prediction of the coexisting compositions of the mixture. Furthermore, it is shown that the interaction energy in this kind of mixture cannot be properly described by using effective potential models usually considered for pure compounds.

On the role of the definition of potential models in Gibbs ensemble phase equilibria simulations of the H 2 S-pentane mixture

The effect of treating explicitly the coulombic and polarization interactions is investigated through the calculation of the coexistence curve of the pentane-H2S binary mixture. In this work, potential models have been developed for hydrogen sulphide and pentane, which include electrostatic sites—estimated from ab initio calculations—and polarizable sites—estimated from experimental data—in addition to Lennard-Jones sites. Compared to existing models, these new models have the same number of fitting parameters to experimental thermodynamic data. They are shown to correctly describe the coexistence curve of the pure compounds. When applied to the case of mixtures, together with Lorentz-Berthelot combining rules, they allow one to obtain a more accurate prediction of the coexisting compositions of the mixture. Furthermore, it is shown that the interaction energy in this kind of mixture cannot be properly described by using effective potential models usually considered for pure compounds.

Comparative study of gas amplification and energy resolution in some argon-based mixtures

A mean gas amplification factor M in mixtures of argon with propane and DME at various pressures ⩽50 kPa is studied. The deviations from the linear dependence of gas gain on high voltage in a semi-log plot are compared with those observed earlier in argon–isobutane mixtures. In all three kinds of mixtures, the magnitude M 0 of the gas gain where deviations start depends on the partial pressure of the admixture. Energy resolution at 5.9 keV has been measured in pure gases and in argon-based mixtures as a function of the gas gain. The best resolution has been obtained at low gas gains, ∼100–200. At these gains better resolution is obtained for mixtures with lower partial pressure of the admixture. At high gas gains energy resolution depends strongly on the admixture partial pressure, and above M 0 it degrades much faster due to avalanche chain formation.

An Interview with Piotr Sommer

South Bend, Indiana, 7 May 2000 W. MARTIN: In your two line poem Grammar, you write: What was, one should speak of in the past tense, / what isn't in some other tongue. The second line strikes me as somewhat utopian. I'm wondering how you became interested in English and English-language poetry and what has motivated your ongoing engagement with it. In particular, is there something like a utopian component to your interest in English-language poetry? PIOTR SOMMER: Well yes, I think there may be one. There is an element of that utopian longing or whatever one longs for when dealing with writing and when one writes. But I can only try to say a few words about it, reconstructing, as I remember it, how it was. It was still very much a time when no one knew much about American poetry or about the British scene, which at the time seemed to include the Irish scene, too. I had begun writing in high school, and went on to university to study English literature by some accident, I used to think, but who knows. I learned the language a bit in high school, and I was interested in literature, so I think I was intuitively hoping that I would learn something there that I wasn't getting, or wasn't hoping to get, from my own Polish background, although I wasn't aware of this yet. The foreign was always intriguing to me. And since in the twentieth century Polish literature was dominated by French poetry, in terms of translations, studying English literature sounded, I gu ess, to a guy of seventeen, eighteen, like a cool thing to do. Also, that was a time when we were getting a lot of the pop scene from Britain. So for that reason, too, it was an absolutely natural thing for me to do. Even though, again, I think I had an intuition that I'm going to really, well, profit somehow from English literature, as a writer, from knowing about it, especially when I started finding stuff, bits and pieces. I remember my first English-language book of contemporary poetry: a Penguin Modern Poets series book, The Mersey Sound, which was an introduction to the Liverpool group: Brian Patten, Roger McGough, Adrian Henri. I got it from an instructor who came from England to teach a semester at the University of Warsaw when I was eighteen or nineteen. So I knew at that point that they were doing something interesting that I knew nothing about, and it seemed like nobody else in Poland did either. I later cured myself a little of the Liverpool connection, although I translated a children's book by B rian Patten once, when my son was still very young, which I have always liked and still feel pretty good about. But that's probably what got me into the British scene at the beginning, while I was discovering that it wasn't just the pop scene that was interesting. And I started looking into other anthologies and texts, which were actually very difficult to get and use, back then. WM: Who else were you reading then, besides the Liverpool poets? PS: I was full of awe and admiration for Rozewicz, Bialoszewski, and Herbert. Rozewicz was my first great inspiration while I was still in high school. But he was in the textbooks, so in a way it wasn't difficult to discover him, and I probably needed discoveries. Then I read all I could get hold of by Miron Bialoszewski, who I discovered through his Diary of the Warsaw Uprising, a book with a somewhat misleading title, suggesting perhaps a boring book about history. And Herbert, who was such a wonderful poet to read, back in those days. All that was quite a discovery. But Bialoszewski very quickly emerged, surfaced for me as the most exciting and most intriguing Polish writer of what now would be the second half of the century. And as for the forefathers who sounded exotic and exciting in a contemporary way, I always loved Kochanowski and Lesmian. And I read plenty of others, so it was a kind of mixture. And I must have slowly come to realize that what I wanted was to escape the postromantic overtones and solemnities which to me sounded rather loud in a lot of Polish writing -- with a few exceptions that I then knew about, like Bialoszewski and, say, Andrzej Bursa. …

Equation of state for fused-hard-sphere fluid mixtures

This paper develops a theoretically-based equation of state for fused-hard-sphere fluid mixtures on the basis of an equation of state previously derived for hard-convex-body fluid mixtures. The equation uses as a reference the equation of state for an equivalent hard-sphere fluid mixture in which each component has the same molecular volume as the effective molecular volume of one of the components of the fused-hard-sphere mixture. The two parameters required by the theory, namely the averaged effective molecular volume of the molecules in the mixture and the corresponding effective non-sphericity parameter, are obtained from the geometrical characteristics of the molecules that form the mixture. The results are, on the whole, in closer agreement with simulation data than those obtained with other theories developed for this kind of mixture.

Phase equilibria of asymmetric hard sphere mixtures

The phase diagram of mixtures of hard spheres with additive diameters is studied. The case of very different sizes is treated by means of mapping the two component system on a one component problem. In this monocomponent system large particles are explicitly considered, whereas the effects of the small component are included through an additional effective interaction potential between large particles. The effective potential is used to analyze the phase diagram of the mixture by means of computer simulation techniques. Results for the behavior at low density of small spheres seem to indicate that no fluid-fluid equlibria occur. On the other hand, the results show how this kind of mixture can exhibit equilibria between isostructural crystalline phases.

Excess molar volumes of liquid 1-bromoalkane + alkane mixtures. Nitta–Chao characterization of the bromine–bromine and bromine–methylene interactions in binary 1-bromoalkane + alkane mixtures

Excess molar volumes at 298.15 K for the binary mixtures of a 1-bromoalkane with a n-alkane are reported. The VE values were obtained from measurements of the density with an Anton Paar densimeter. Literature data of excess Gibbs energies, excess enthalpies, excess volumes, and activity coefficients at infinite dilution for this kind of mixtures together with molar volumes and vaporization enthalpies of pure bromoalkanes were used to calculate the characteristic parameters of the Nitta-Chao group contribution model. With the obtained parameters, this model consistently describes the experimental data of the 1-bromoalkane + n-alkane mixtures. Furthermore, we have determined the energetic parameters for the Larsen version of the UNIFAC model.Key words: liquids, mixtures, thermodynamics, group contributions.

Excess molar volumes of liquid 1-bromoalkane + alkane mixtures. Nitta-Chao characterization of the bromine-bromine and bromine-methylene interactions in binary 1-bromoalkane + alkane mixtures

Excess molar volumes at 298.15 K for the binary mixtures of a 1-bromoalkane with a n-alkane are reported. The V E values were obtained from measurements of the density with an Anton Paar densimeter. Literature data of excess Gibbs energies, excess enthalpies, excess volumes, and activity coefficients at infinite dilution for this kind of mixtures together with molar volumes and vaporization enthalpies of pure bromoalkanes were used to calculate the characteristic parameters of the Nitta-Chao group contribution model. With the obtained parameters, this model consistently describes the experimental data of the 1-bromoalkane + n-alkane mixtures. Furthermore, we have determined the energetic parameters for the Larsen version of the UNIFAC model.

Excess properties for cyclohexanone + butanols at 298.15 K

Densities, viscosities, and refractive indexes of the binary systems cyclohexanone + n-butanol, + sec-butanol, and + 2-methyl-1-propanol have been measured at 298.15 K and atmospheric pressure, over the whole composition range. The excess values of molar volume, viscosity, Gibbs free energy of activation of viscous flow, and internal pressure were calculated from experimental measurements. Based on the variations of the excess functions with composition, conclusions about the molecular interactions in these kinds of mixtures were obtained. Keywords: excess properties, binary mixtures, butanols, cyclohexanone.

Infrared Chemical Micro-Imaging Assisted by Interactive Self-Modeling Multivariate Analysis

In the analytical environment, spectral data resulting from analysis of samples often represent mixtures of several components. Extraction of information about pure components from that kind of mixture is a major problem, especially when reference spectra are not available. Self-modeling multivariate mixture analysis has been developed for this type of problem. In this paper, two examples will be used to show the potential of the technique for vibrational spectroscopy. Infrared microspectroscopic chemical imaging has been employed to improve spatial resolution for distinguishing differences between adjacent, nonidentical materials. The resolution of a 2- to 3- μm-thick inner layer, from a four-layer polymer laminate, has been achieved. The same approach has been utilized to extract pure component spectra out of a KBr pellet of a mixture of three compounds.

Measurements and analysis of the excess enthalpies of some dichloroalkane + 2-ketone systems using UNIFAC group-contribution model

Experimental excess molar enthalpies hE at 298.15 K and normal atmospheric pressure were obtained for the binary mixtures 1,2-dichloropropane + (2-propanone, 2-butanone, or 2-pentanone), 1,3-dichloropropane + (2-butanone or 2-pentanone), 1,4-dichlorobutane + (2-butanone or 2-pentanone) using a Calvet microcalorimeter. The hE values for all the mixtures were negative. The experimental results used to test the capability of the interaction parameters of two versions of the UNIFAC group-contribution model to predict the proximity effect in these kind of mixtures.

Cleft palates and liver weight data of two different mixtures of PCDDs in pregnant mice related to organ dosage

Three doses of two different mixtures of PCDD homologues and congeners were administered on day 9 of pregnancy to C57BL/6J (B6) or DBA/2J (D2) mice. Doses given to D2 mice were tenfold higher than those given to B6 mice. In addition, 2,3,7,8-TCDD (15 μg/kg and 150 μg/kg b.w. resp.) was tested separately as well as in combination with the applied doses of the PCDD mixtures. On day 18 of pregnancy the mice were sacrificed, organ weight data were taken, and the number of fetuses with cleft palates was determined. Liver weight was significantly increased in all treated D2 mice, however, in B6 mice only when 2,3,7,8-TCDD was co-administered. The incidence of cleft palates were dose-dependent in the fetuses of D2 mice. In B6 mice this malformation occured either after the administration of 2,3,7,8-TCDD alone or with 2,3,7,8-TCDD added to the different PCDD mixtures. The concentration of the 2,3,7,8-substituted PCDDs analysed in the liver and white adipose tissue reflect the doses and the kind of mixture given orally. However, in the liver of B6 mice, organ dosages (expressed as I-TEQ) obviously do not correspond to the administered increasing dosages. It is concluded that there is some additive effect for TCDD and the 2,3,7,8-substituted congeners.