Complete Composition Range Research Articles

The permittivity of thermodynamically ideal liquid mixtures and the excess relative permittivity of binary dielectrics

The ideal relative permittivity of liquid mixtures is demonstrated to be a volume-fraction-weighted average of the pure-component relative permittivities. This generalised-thermodynamics result is used to define the molar electric dipole, permittivity, dielectric polarization and electric susceptibility of thermodynamically ideal liquid mixtures and the corresponding excess properties. A hyperbolic approach is developed to the analysis of averaging formulae that are frequently used to predict the effective permittivity of composite materials. Some of these formulae are shown to be segments of rectangular hyperbolae with fixed asymptote values, whereas others can be understood in terms of rectangular hyperbolae with composition-dependent asymptote values. Relative permittivities of binary mixtures between tetraglyme and hexane, cyclohexane or benzene covering the complete composition range are reported at various temperatures. These data are used to outline a novel method for analysing the excess relative permittivity of liquid mixtures.

Size and composition effects on the melting of bimetallic Cu–Ni clusters studied via molecular dynamics simulation

The melting points of bulk Cu–Ni over the complete range of compositions were simulated by a model of molecular dynamics with general embedded atom method (EAM). The melting point of bimetallic Cu–Ni clusters was also studied by using the same model. The results show that the changing trend of the simulated melting points for the bulk Cu–Ni agrees with the experimental phase diagram very well. The melting point of the cluster increases with the increase of Ni composition and the increasing trend agrees well with the theoretical phase diagram of bimetallic nanoparticles. The melting point of the cluster is higher than those of clusters without segregation and composition-dependent because the segregation of Cu atoms decreases the melting point. The simulation for the size-dependent melting points of the clusters with 20%, 50%, and 80% Ni shows a linear relation between the inverse cluster sizes and the melting points. The linear relation is not affected by the segregation.

Conductance and Solvation Behavior of Quinolinium Dichromate in Binary Mixtures of Water with N,N-Dimethyl Formamide

Conductance of quinolinium dichromate has been measured in water and N,N-dimethyl formamide mixtures over the complete compositional range. The limiting molar conductance Λo and the association constant of the ion pair, KA, have been computed using the Shedlovsky equation. Λo increases with an increase in the proportion of water in the solvent mixture. The Kraus−Bray equation has also been used to correlate the limiting molar conductance data, and the dissociation constant of the ion pair, KC, has been computed. The results have been discussed in terms of ion−solvent interactions.

Helium isotopes in early Iceland plume picrites: Constraints on the composition of high 3He/ 4He mantle

A detailed study of the geochemistry of a new suite of early Iceland plume picrites shows that extremely high 3He/ 4He ratios (up to 50 R a) are found in picrites from Baffin Island and West Greenland. High 3He/ 4He picrites display a wide range in 87Sr/ 86Sr (0.70288–0.70403), 143Nd/ 144Nd (0.51288–0.51308) and incompatible trace element ratios (e.g. La/Sm n = 0.5–1.6). These overlap the complete range of compositions of mid-ocean ridge basalts and most northern hemisphere ocean island basalts, including Iceland. Crustal contamination modelling in which high-grade Proterozoic crustal basement rocks for the region are mixed with a depleted parent cannot account for the trend displayed by the Baffin Island and West Greenland picrites. This rules out the possibility that the incompatible trace element, Sr and Nd isotope range of the high 3He/ 4He picrites is due to crustal contamination. The compositional range at high 3He/ 4He is also inconsistent with derivation from a primordial-He-rich reservoir that is a residue of ancient mantle depletion. This implies that the composition of the high 3He/ 4He mantle cannot be determined simply by extrapolating ocean island basalt He–Sr–Nd–Pb–Os isotope data. The apparent decoupling of He from trace element and lithophile radiogenic isotope tracers is difficult to attain by simple mixing of a high-[He], high 3He/ 4He reservoir with various depleted and enriched He-poor mantle reservoirs. The possibility that primordial He has diffused into a reservoir with a composition typical of convecting upper mantle cannot be ruled out. If so, the process must have occurred after the development of existing mantle heterogeneity, and requires the existence of a deep, primordial He-rich reservoir.

Excess molar volumes, viscosity deviations, excess isentropic compressibilities and deviations in relative permittivities of (alkyl acetates (methyl, ethyl, butyl and isoamyl) + n-hexane, + benzene, + toluene, + ( o-, m-, p-) xylenes, + (chloro-, bromo-, nitro-) benzene at temperatures from 298.15 to 313.15 K

The experimental densities ( ρ), dynamic viscosities ( η), speeds of sound ( υ) and relative permittivities ( ε r) of thirty six binary mixtures of esters (methyl acetate, ethyl acetate, butyl acetate and isoamyl acetate) + organic solvents ( n-hexane, benzene, toluene, o-, m-, p- xylenes), + halogenated benzene (chloro-, bromobenzene), + nitrobenzene have been measured over the complete composition range at atmospheric pressure and temperatures (298.15 to 313.15 K). The excess molar volumes, V m E, excess isentropic compressibilities, κ s E, deviations in relative permittivities, δ ε r have been calculated and fitted to Redlisch–Kister type equation. The dynamic and kinematic viscosities have been correlated through Grunberg–Nissan and MacAllister equations. The qualitative analysis of various functions revealed that i.) esters lose their dipolar association in presence of inert and unlike n-hexane, ii.) specific but weaker n… π type interactions predominate in binary mixtures of esters + aromatic organic solvents and iii.) weak electron donor–acceptor complexes predominate in the mixtures of esters with halogenated and nitrated benzene.

Thermophysical Properties of Binary Mixtures of Methanol with Chlorobenzene and Bromobenzene from 293 K to 313 K

Densities and viscosities have been measured for the binary mixtures of methanol with chlorobenzene and with bromobenzene from 293 K to 313 K over the complete composition range. Densities were used to compute the excess molar volume (\({V_{\rm m}^{\rm E})}\) , for these binary systems. The results have been discussed in terms of molecular interactions. Furthermore, viscosity results were compared with a corresponding-states model. The average absolute deviation was found to be 1.9 %.

Thermophysical Properties for Diethylene Glycol + Nitrobenzene and Triethylene Glycol + (Chloro-, Bromo-, Nitro-) Benzene Systems at Different Temperatures

The densities, viscosities, sound speeds, and relative permittivities for four binary mixtures of glycols+organic solvents that are miscible over the complete composition range, namely, diethylene glycol (DEG)+nitrobenzene and triethylene glycol (TEG)+chlorobenzene, +bromobenzene, and +nitrobenzene have been measured at atmospheric pressure and at temperatures from 298.15 to 313.15 K. The excess molar volumes are calculated and fitted with a Redlich–Kister type equation. The qualitative analysis of excess molar volumes revealed that the structure-making effects probably in the form of weak Cl· · ·H–O hydrogen bonding, Cl· · ·O electron acceptor–donor interactions, and interstitial accommodation of chlorobenzene in associate structures of triethylene glycol, etc. are predominant in these mixtures.

Compatibility, rheological, and thermal properties of the melt blends of PEN (HQ/PP) with PEN (HQ/RS)

AbstractTwo kinds of polyarylene ether nitriles (PEN) copolymers PEN (HQ/PP) and PEN (HQ/RS) were synthesized using 2,6‐dicholorobenzonitrile (DCBN) with equal molar of phenolphthalein (PP) and hydroquinone (HQ), DCBN with equal molar of HQ and resorcin (RS), respectively. The melt‐mixed blends of two PENs over the complete composition range were characterized by dynamic mechanical analyses (DMA), tensile testing, scanning electronic microscopy (SEM), and capillary rheometer test for their compatibility, thermal, mechanical, and melt flow properties study. DMA show a considerable compatibility between the two PENs. Morphology examinations reveal good component dispersion and strong interface adhesion. The capillary rheometer test found that the blending of PEN (HQ/RS) enhanced the fluidity of the PEN (HQ/PP)/PEN (HQ/RS) blends by reducing its viscosity, which is beneficial to the processability of PEN (HQ/PP). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Speeds of sound and isentropic compressibilities of binary mixtures of 1-heptanol + 1,2-dichloroethane, +1,1,1-trichloroethane, +1,1,2,2-tetrachloroethane, +trichloroethylene and +tetrachloroethylene at 303.15 K – comparison with theories

Densities ρ, and speeds of sound u, of the binary mixtures of 1-heptanol with 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2,2-tetrachloroethane, trichloroethylene, and tetrachloroethylene have been measured over the complete composition range at 303.15 K. Isentropic compressibility κs, and Isentropic compressibility deviations Δκs were calculated, and were correlated by a Redlich–Kister type function to determine the fitting parameters and the SDs. The results are consistent with the self-association of 1-heptanol and the polar and nonpolar characters of used chloroethanes or chloroethylenes, which produce the dissociation of 1-heptanol. Speeds of sound and isentropic compressibilities have been compared with calculated values from Jacobson free length theory, Schaaff collision factor theory, Nomoto relation, Junjie relation and Van Deal ideal mixing relation.

Prediction dielectric constant of different ternary liquid mixtures at various temperatures and compositions using artificial neural networks

Artificial neural networks (ANNs) were successfully developed for the modeling and prediction dielectric constant of different ternary liquid mixtures at various temperatures (−10°C ≤ t ≤ 80°C) and over the complete composition range (0 ≤ x 1, x 2, x 3 ≤ 1). A three-layered feed forward ANN with architecture 7-16-1 was generated using seven parameters as inputs and its output is dielectric constant of media. It was found that properly selected and trained neural network could fairly represent the dependence of dielectric constant of different ternary liquid mixtures on temperature and composition. For the evaluation of the predictive power of the generated ANN, an optimized network was applied for predicting the dielectric constant in the prediction set, which were not used in the modeling procedure. Squared correlation coefficient (R 2) and root mean square error for prediction set are 0.9997 and 0.2060, respectively. The mean percent deviation (MPD) for the property in the prediction set is 0.8892%. The results show nonlinear dependence of dielectric constant of ternary mixed solvent systems on temperature and composition is significant.

Density and Speed of Sound of Binary Mixtures of N-Methyldiethanolamine and Triethanolamine with Ethanol

In the present paper, density and speed of sound of binary systems formed by ethanol and two amines (N-methyldiethanolamine and triethanolamine) at several temperatures (15, 20, 25, 30, 35, and 40 °C) have been determined. The study of these mixtures has covered its complete composition range. Experimental values of these physical properties have been employed to calculate the isentropic compressibility value.

The phase equilibrium diagram for the Fe-Nb-Ti System

Microstructure analysis, differential thermal analysis, x-ray diffraction, and electron probe microanalysis have been applied to the phase equilibria in the Fe-Nb-Ti ternary system over the complete composition range. The 950 °C isothermal section of the diagram has been constructed. Positions have been determined for the monovariant transformation lines in the melting diagram. No ternary intermetallides have been found.

Measurements of Density and Refractive Index of Soybean Oil + Short Aliphatic Alcohols

Densities and refractive indices of binary mixtures containing soybean oil + (methanol, ethanol, 1-propanol, 2-propanol, or 1-butanol) have been measured from 283.15 to 298.15 K at atmospheric pressure, over the complete homogeneous composition range. Derived properties, such as excess molar volumes, partial excess molar volumes, and excess isobaric compressibilities, have been determined. Values of physical properties were compared with the results obtained by different prediction methods; the results were analyzed according to the non-ideality and large differences of molecular characteristics of the compounds included in this study.

Ternary blends of acrylic rubber, poly(butylene terephthalate), and liquid crystalline polymer: Influence of interactions on thermal and dynamic mechanical properties

AbstractThe ternary blends of acrylate rubber (ACM), poly(butylene terephthalate) (PBT), and liquid crystalline polymer (LCP) were prepared by varying the amount of LCP but fixing the ratio of ACM and PBT, using melt mixing procedure. The influence of interactions on thermal and dynamic mechanical properties of the blends was investigated over the complete composition range. The techniques applied were Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetry (TG), and dynamic mechanical analysis (DMA). The FTIR spectroscopy analysis showed reduction in the intensity of the peak corresponding to epoxy groups of ACM with increasing heating time at 290°C. This implies that there is a chemical reaction between the epoxy and end groups of PBT and LCP. Glass transition temperature (Tg) and melting temperature (Tm) of the blends were affected depending on the LCP weight percent in the ACM/PBT blend, respectively. This further suggests the strong interfacial interactions between the blend components. In presence of ACM, the nucleating effect of LCP was more pronounced for the PBT phase. The thermogravimetric study showed improved thermal stability for the blends with the increasing LCP content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3904–3912, 2006

Thermodynamic assessment of the Ce–Y system

Experimental data for the Ce–Y system were critically evaluated using the CALPHAD approach. All phases were treated as substitutional solution phases for which the excess Gibbs energies were modeled with Redlich–Kister polynomial functions. Our analysis relies on phase diagram data, because no other thermodynamic data are present to constrain the model parameters in the excess Gibbs energy functions. It results in a consistent formulation of the Gibbs energies of all phases in this system. Based on our analysis, we propose a new constitutional phase diagram for Ce–Y covering a temperature range between 300 K and 1800 K and a complete composition range.

Studies of dynamic viscosity and Gibbs energy of activation of binary mixtures of methylcyclohexane with n-alkanes (C 5–C 10) at various temperatures

Dynamic viscosities, η, for binary mixtures of methylcyclohexane with some n-alkanes, namely, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane have been measured over the complete composition range at the temperatures 293.15 K, 298.15 K and 303.15 K and normal atmospheric pressure. Viscosity deviations Δln η, and excess Gibbs energy of activation Δ G* E, were calculated therefrom and were correlated by a Redlich–Kister type function in terms of mole fractions. For mixtures of methylcyclohexane with the studied n-alkanes Δln η is negative at all three temperatures. The Δ G* E values show positive values for the binary mixtures with n-decane, whereas negative values were observed for all remaining binary mixtures. An inversion of sign was observed for the mixtures with n-nonane at the rich mole fraction of methylcyclohexane. The Grunberg and Nissan and the McAllister three-body interaction models have also been used to correlate the kinematic viscosities of binary liquid mixtures with mole fractions.

Speed of Sound and Isentropic Compressibility of Aqueous Solutions of Pyrrolidine and Piperidine

In the present paper, speed of sound and isentropic compressibility of aqueous solutions of two amines, pyrrolidine (C4H9N) and piperidine (C5H11N), at several temperatures (293, 303, 313, and 323 K) have been determined. The study of these mixtures has covered its complete composition range. Speed of sound shows a maximum value when the presence of amines increases in the mixture. A Redlich−Kister type equation was employed to fit the excess properties.

Two calorimetric glass transitions do not necessarily indicate immiscibility: The case of PEO/PMMA

AbstractDifferential scanning calorimetry has been used to examine blends of a poly(ethylene oxide) (PEO), Mn = 300 g/mol, and a poly(methylmethacrylate) (PMMA), Mn = 10,000 g/mol, across the complete composition range. The relatively low molar mass of the PEO minimizes interference from crystallization. In the midrange of composition, ∼25–70% PEO, two broad, but distinct, glass transitions are resolved. These are interpreted as distinct glass transitions of the two components, as anticipated by the self‐concentration model of Lodge and McLeish. The composition dependence of the observed transitions is well described by the self‐concentration approach, using lengthscales of approximately two‐thirds of the Kuhn length. The results are compared with previous measurements on PEO/PMMA blends and other miscible systems. The principal, general conclusion is that one should actually expect two glass transitions in a miscible polymer blend or polymer solution; the rule of thumb that two transitions indicate immiscibility is incorrect. Furthermore, attempts to rationalize two transitions on the basis of incomplete segmental mixing, or other unspecified “nanoheterogeneity,” may not be justified in many cases. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 756–763, 2006

Excess molar volumes and dynamic viscosities for binary mixtures of toluene + n-alkanes (C 5–C 10) at T = 298.15 K – Comparison with Prigogine–Flory–Patterson theory

Densities ρ, dynamic viscosities η, for binary mixtures of toluene with some n-alkanes, namely, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, and n-decane have been measured over the complete composition range. Excess molar volumes V E, viscosity deviations Δ η, and excess Gibbs free energy of activation Δ G ∗E, were calculated there from and were correlated by Redlich–Kister type function in terms of mole fractions. For mixtures of toluene with n-pentane and n-hexane the V E is negative and for the remaining systems is positive. The Δ η values are negative for all the studied mixtures. The Δ G ∗E values shows the positive values for the binary mixtures with n-decane, whereas the negative values have been observed for all the remaining binary mixtures. From the results, the excess thermal expansivities at constant pressure α E, is also estimated. The Prigogine–Flory–Patterson (PFP) theory and its applicability in predicting V E is tested. The results obtained for viscosity of binary mixtures were used to test the semi-empirical relations of Grunberg and Nissan, Tamura and Kurata, Hind et al., Katti and Chaudhri, McAllister, Heric, Kendall, and Monroe. The experimental on the constituted binaries are analyzed to discus the nature and strength of intermolecular interactions in these mixtures.

Densities and Viscosities of Aqueous Solutions of Pyrrolidine and Piperidine from (20 to 50) °C

In the present paper, density and kinematic viscosity have been determined for aqueous solutions of two amines (pyrrolidine and piperidine) at (20, 30, 40, and 50) °C. The study of these mixtures has covered its complete composition range. Density shows the typical behavior of the composition and temperature's effect, but viscosity shows a maximum with an increased amine composition. A Redlich−Kister type equation was employed to fit the excess properties.