Showing papers on "Binary system published in 1985"

A new model for upper and lower critical solution temperatures in poly(ethylene oxide) solutions

Abstract: Diagramme de phases du systeme PEO-eau calcule en utilisant la theorie de Flory; accord semi-quantitatif avec l'experience

Critical behavior of the binary fluids cyclohexane-methanol, deuterated cyclohexane-methanol and of their isodensity mixture: Application to microgravity simulations and wetting phenomena.

Abstract: It is possible to adjust the density of cyclohexane by adding a small amount of deuterated cyclohexane. Then the mixture deuterated cyclohexane-cyclohexane-methanol can be made isopycnic. We have determined the critical properties of this system and of the systems cyclohexane-methanol and deuterated cyclohexane-methanol: coexistence curve, correlation length, and osmotic compressibility via refractive index and turbidity measurements. For that purpose, a detailed discussion of the validity of the volume additivity and of the Lorentz-Lorenz formula has been made. The main result is that the isopycnic system acts as a binary mixture for the phase transition properties as shown by the \ensuremath{\beta} exponent and the amplitude combinations (${R}_{\ensuremath{\xi}}^{+}$${R}_{c}^{\mathrm{\ensuremath{-}}1/3}$) which exhibit the universal values. Some aspects of microgravity conditions can then be created. We have studied in the isopycnic system the phase separation at critical concentration; new features are found after a thermal quench: macroscopic spinodal decomposition structures during the phase separation process and macroscopic wetting layers in the final equilibrium state.

Compatibilizing effect of random or block copolymer added to binary mixture of homopolymers

Abstract: : When copolymer A-B is added to the mixture of homopolymer A and homopolymer B, the compatibility between the two homopolymers is enhanced under certain conditions. Analysis, based on the Flory-Huggins free energy of mixing, gives the specific conditions under which the critical, spinodal or binodal temperature of the ternary mixture is expected to be lowered linearly with the amount of the added copolymer. Experimental measurements were performed on the changes in the cloud point of the mixtures of polystyrene and polybutadiene to which varying amounts of styrene/butadiene random or diblock copolymer were added. The results agree with the theoretical expectation. From quantitative analysis of the cloud point depression, the temeprature coefficient of the interaction energy density between styrene and butadiene polymers is determined. The temperature coefficient is found to give an excellent agreement with the value previously determined by a curve fitting procedure applied to the cloud point curves of binary mixtures.

Viscosities and densities of binary liquid mixtures of m-cresol with substituted anilines. Part 3

Abstract: Densities and viscosities were determined for the binary systems of m-cresol with aniline, N-methylaniline, N, N-dimethylaniline, N-ethylaniline, and N, N-diethylaniline at five different temperatures. From the experimental results, the excess volume, excess viscosity, excess molar free energy of activation of flow, excess partial molar volume, and partial molar volumes were calculated. Also various thermodynamic parameters of activation of flow were calculated from the dependence of viscosity on temperature. The deviations from ideality of thermodynamic and transport functions are explained on the basis of molecular interactions between the components of the mixture.

MEASUREMENTS AND CORRELATION OF THE THERMAL CONDUCTIVITY OF LIQUID n-PARAFFIN HYDROCARBONS AND THEIR BINARY AND TERNARY MIXTURES.

Abstract: The thermal conductivity of four pure normal paraffin hydrocarbons (C11, C14, C15, C16) and binary and ternary mixtures of three n-paraffin hydrocarbons (C7, C11, C16) have been measured in the temperature range from about 20 to 90°C at atmospheric pressure. Measurements have been performed with the aid of a fully automated transient hot-wire instrument. The accuracy of the reported data is estimated to be ±1.0 to ±1.5%. A new simple and practical equation, which can calculate the thermal conductivity of pure n-paraffin hydrocarbons (4≤n≤ 16) with the uncertainty of ±1%, has been correlated in terms of temperature and number of carbon atoms based on the present results including some other reliable data. Also, a mixing rule for the mixtures of n-paraffin hydrocarbons was proposed and was adequately confirmed by the present results within the experimental error.

Characterization of cooperative conformational transitions by Fourier transform infrared spectroscopy: application to phospholipid binary mixtures'

Abstract: Temperature-induced cooperative conformational transitions in biopolymers may be examined in aqueous solution by the use of Fourier transform infrared spectroscopy The transition is described in terms of a two-state model with a fractional population parameter (which describes the degree of transition at various values intermediate between the two limiting cases) that can be generated by a least-squares technique This procedure allows for calculation of a conformational index without assuming a linear dependence of the infrared parameter on the extent of transition Calculations based on the Zimm–Bragg theory of cooperative conformational transitions allow thermodynamic quantities to be derived using the conformational index in conjunction with calorimetric measurementsThe method is illustrated with data from the gel/liquid-crystalline phase transitions of binary phospholipid vesicles where the use of isotopic substitution allows the conformation of each component of the binary mixture to be independen

Transport properties of nonelectrolyte liquid mixtures—VI. Viscosimetric study of binary mixtures of hexafluorobenzene with aromatic hydrocarbons

Abstract: Viscosity coefficients for binary mixtures of hexafluorobenzene with benzene, toluene, para-xylene, and mesitylene have been measured along the saturation line at temperatures from 15 to 120°C using specially designed capillary viscometers. Densities were measured using a pyknometer and volume-change apparatus. Deviations of the viscosities from a rectilinear dependence on mole fraction are consistent with enhanced interactions between unlike species, which increase with increasing number of methyl groups on the aromatic hydrocarbon and decrease with increasing temperature. The application of the Grunberg and Nissan equation, the Hildebrand equation, and energy of activation theories to these results is examined.

Evolution of rotationally and tidally distorted low-mass, close binary systems - Implications for the minimum orbital period of cataclysmic variables

Abstract: A (1 + 0.4) solar mass close binary system consisting of a compact primary and a red dwarf secondary has been evolved numerically. Such a binary system should effectively model cataclysmic variables for which a minimum orbital period cutoff of about 81 minutes has been observed. The influence of gravitational radiation losses which drive Roche lobe overflow has been studied, and the effects of rotational and tidal distortion have also been incorporated in the calculation. The evolution of the He-3 abundance, which has been suggested as a possible explanation for the upper limit of the apparent orbital period gap exhibited by cataclysmic variables, is also considered. It is found that both the distortional effects and the He-3 chemical profile can play an important role in determining the subsequent evolution of these systems. Specifically, when distortion is included, the theoretical minimum orbital period is increased by about 10 percent, yielding better agreement with observations.

The mass-radius relation in binary systems

Abstract: The mass-radius relation is determined for Main-Sequence stars from observational data of well-detached binary systems. The results are compared to previous empirical relations and we discuss their application to the study of the light curves of eclipsing binaries. A comparison with theoretical Main-Sequence models has been carried out.

Thermodynamic considerations of metal halide vapour complexes

Abstract: Certain metal halide vapour complexes of the type ABX m+n increase the equilibrium vapour concentration of one or both of the component salts in the binary system (AXm/BXn). Such enhancement depends upon the free energy of complex formation, the saturated vapour pressure of the complexing salt and the melt activities, in a manner formulated here by means of a thermodynamic scheme. Certain trends in the periodic table are established.

Density of an equimolar mixture of ethane and methyl chloride

Abstract: We have measured the density of an equimolar gas mixture of C2H6–CH3Cl between 323.15 and 473.15 K at pressures to 14.0 MPa. Interaction second virial coefficients and dew-point pressures are extracted from the measurements. Intermolecular force constants for the Lennard-Jones and Stockmayer models are determined optimally for like and unlike pair interactions. Recent methods of prediction for second virial coefficients, both pure and interaction, are tested against experiment.

Surface transitions in binary liquid mixtures

Abstract: Using a reasoning based on the classical thermodynamics of adsorption, the occurrence of a surface transition is described in terms of a phase diagram. The surfaces involved are the liquid-vapor and liquid-solid interfaces, when only physisorption takes place. Cahn's conclusion concerning the existence of a prewetting line in the monophasic zone of the phase diagram of the binary system has been verified. Two experimental examples have been considered, viz., the methanol-cyclohexane and water-2-butoxyethanol systems.