Pressure Dependence of the Melting and Self Diffusion in 2,2-dimethylpropane, 2,2-dimethylpropionitrile, and 2-methylpropanol-2

1984 ◽  
Vol 39 (8) ◽  
pp. 800-806 ◽  
Author(s):  
M. Woznyj ◽  
F. X. Prielmeier ◽  
H.-D. Lüdemann
Keyword(s):  
Pressure Dependence ◽  
Diffusion Coefficients ◽  
High Pressures ◽  
The Self ◽  
Pressure Curve ◽  
Hard Sphere Model ◽  
Sphere Model ◽  
Melting Pressure ◽  
Self Diffusion ◽  
Straight Lines

The melting pressure curves of 2,2-dimethylpropane, 2,2-dimethylpropionitrile and 2-methylpropanol- 2 and the pressure dependence of the hex ⇔ fee transition of 2,2-dimethylpropane have been determined in the pressure range between 0.1 and 200 MPa. The self diffusion coefficients D in the liquid state of the three compounds have been determined as function of pressure (pmax ≧ 120 MPa) from the melting pressure curve up to ca. 450 K. At high temperatures and high pressures the self diffusion coefficients of the three compounds become rather similar. The influence of the hydroxylgroup upon the diffusivity of (CH3)3COD is most clearly seen at the lowest temperatures. The isobars of C(CH3)4 and (CH3)3CCN are straight lines with identical slopes. For (CH3)3COD all isobars show a curvature. From the data in the Arrhenius representation activation volumes and activation energies are derived. For C (CH3)4 the density dependence of D can be described with the rough hard sphere model.

p, T Dependence of the Self Diffusion Coefficients and Densities in Liquid Silicone Oils

1996 ◽  
Vol 51 (3) ◽  
pp. 192-196 ◽  
Author(s):  
A. Thern ◽  
H.-D. Lüdemann
Keyword(s):  
Diffusion Coefficients ◽  
Hard Sphere ◽  
The Self ◽  
Hard Sphere Model ◽  
Tait Equation ◽  
Sphere Model ◽  
Rouse Model ◽  
Self Diffusion ◽  
Silicone Oils ◽  
Liquid Silicone

Abstract Self diffusion coefficients and densities from a series of commercial silicones have been studied in the temperature range between 290 and 410 K at pressures up to 200 MPa. The densities are fitted to a modified Tait equation. The self diffusion coefficients are discussed in terms of the rough hard sphere model and tested against the Rouse-model.

p, T-Dependence of Self Diffusion in Mixtures of Hexane/Ethanol and Hexane/Dimethylether

1995 ◽  
Vol 50 (2-3) ◽  
pp. 149-154 ◽  
Author(s):  
A. Heinrich-Schramm ◽  
W. E. Price ◽  
H.-D. Lüdemann
Keyword(s):  
Hydrogen Bonding ◽  
Qualitative Analysis ◽  
Pressure Dependence ◽  
Diffusion Coefficients ◽  
Low Temperatures ◽  
The Self ◽  
Slight Effect ◽  
Self Diffusion ◽  
Dipole Interactions ◽  
Significant Difference

Abstract Self-diffusion in ethanol/hexane and dimethylether/hexane mixtures of various compositions has been measured at 215-350 K and up to 200 MPa. Qualitative analysis of the results indicates that, as expected, hydrogen bonding retards the self-diffusion of ethanol in the mixture, especially at the low temperatures. Dimethylether shows a slight effect of dipole-dipole interactions on the self-diffu­sion, as seen by a higher ΔE* value than for the alkane. However there is no significant difference in the pressure dependence for both mixtures. This is shown by considering the ratio of the two diffusion coefficients, which suggests that, contrary to what is observed for pure alcohols, pressure has little effect upon the hydrogen bonding of ethanol in the mixture. In additon, there is surprisingly little concentration dependence on the ratios for either mixture.

Composition and Pressure Dependence of the Diffusion Coefficients in Binary Liquid Alloys

2010 ◽  
Vol 297-301 ◽  
pp. 1371-1376
Author(s):  
Dezső L. Beke
Keyword(s):  
Activation Energy ◽  
Melting Point ◽  
Pressure Dependence ◽  
Diffusion Coefficients ◽  
The Self ◽  
Interatomic Potentials ◽  
Liquid Alloys ◽  
Diffusion In Solids ◽  
Self Diffusion ◽  
Binary Liquid

There are a number of well-known empirical relations for diffusion in solids. For example the proportionality between the self-diffusion activation energy and melting point or between the entropy of the diffusion and the ratio of activation energy and the melting point (Zener rule) are perhaps the best known ‘rules of thumb’. We have shown earlier in our Laboratory, that these relations are direct consequences of the similarity of interatomic potentials seen by ions in solids. On the basis of this, similar relations were extended for impurity and self diffusion in binary solid alloys. In this paper, results for binary liquid mixtures will be reviewed. First a minimum derivation of the temperature dependence of the self-diffusion coefficient, D, is presented (minimum derivation in the sense that it states only that the reduced (dimensionless) D should be a universal function of the reduced temperature), using the similarity of interatomic potentials and dimensional analysis. Then the extension of this relation for determination of the pressure and composition dependence of the self-diffusion coefficients is described using pressure and composition dependent scaling parameters (melting point, atomic volume and mass). The obtained universal form (valid for binary liquid alloys) is very useful for the estimation of the temperature, composition and pressure dependence of the self-diffusion coefficients. Finally, the relation for the ratio of the impurity and self-diffusion coefficients is derived.

scholarly journals Self-Diffusion Coefficients, Aggregation Numbers and the Range of Existence of Spherical Micelles of Oxyethylated Alkylphenols

2021 ◽  
Author(s):  
Victor P. Arkhipov ◽  
Natalia A. Kuzina ◽  
Andrei Filippov
Keyword(s):  
Aqueous Solutions ◽  
Diffusion Coefficients ◽  
The Self ◽  
Self Diffusion ◽  
Aggregation Numbers ◽  
Temperature Ranges ◽  
Spherical Micelles ◽  
Limiting Values

AbstractAggregation numbers were calculated based on measurements of the self-diffusion coefficients, the effective hydrodynamic radii of micelles and aggregates of oxyethylated alkylphenols in aqueous solutions. On the assumption that the radii of spherical micelles are equal to the lengths of fully extended neonol molecules, the limiting values of aggregation numbers corresponding to spherically shaped neonol micelles were calculated. The concentration and temperature ranges under which spherical micelles of neonols are formed were determined.

Concentration dependence of the self-diffusion coefficients of water in electrolyte solutions

1974 ◽  
Vol 14 (6) ◽  
pp. 915-918
Author(s):  
A. M. Sazonov ◽  
V. M. Olevskii ◽  
A. B. Porai-Koshits ◽  
V. N. Skobolev ◽  
G. A. Shmuilovich
Keyword(s):  
Concentration Dependence ◽  
Diffusion Coefficients ◽  
Electrolyte Solutions ◽  
The Self ◽  
Self Diffusion

scholarly journals Self-Diffusion Coefficients of Methane/n-Hexane Mixtures at High Pressures: An Evaluation of the Finite-Size Effect and a Comparison of Force Fields

2019 ◽  
Author(s):  
Thiago José Pinheiro dos Santos ◽  
Charlles Abreu ◽  
Bruno Horta ◽  
Frederico W. Tavares
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficients ◽  
High Pressures ◽  
Force Fields ◽  
Transport Coefficients ◽  
Finite Size ◽  
Finite Size Effect ◽  
Self Diffusion ◽  
Analytical Correction ◽  
Dynamics Simulations

Mass transport coefficients play an important role in process design and in compositional grading of oil reservoirs. As experimental measurements of these properties can be costly and hazardous, Molecular Dynamics simulations emerge as an alternative approach. In this work, we used Molecular Dynamics to calculate the self-diffusion coefficients of methane/n-hexane mixtures at different conditions, in both liquid and supercritical phases. We evaluated how the finite box size and the choice of the force field affect the calculated properties at high pressures. Results show a strong dependency between self-diffusion and the simulation box size. The Yeh-Hummer analytical correction [J. Phys. Chem. B, 108, 15873 (2004)] can attenuate this effect, but sometimes makes the results depart from experimental data due to issues concerning the force fields. We have also found that different all-atom and united-atom models can produce biased results due to caging effects and to different dihedral configurations of the n-alkane.

scholarly journals Investigation of the Self-Diffusion Coefficients of Trivalent Gd3+ in aqueous solutions: The Effect of Hydrolysis and nitrate ion association

2012 ◽  
Vol 1 (6) ◽  
pp. 334-346 ◽  
Author(s):  
Rafik Besbes ◽  
Noureddine Ouerfelli ◽  
Manef Abderabba ◽  
Patric Lindqvist-Reis ◽  
Habib Latrous
Keyword(s):  
Aqueous Solutions ◽  
Diffusion Coefficients ◽  
Ion Association ◽  
The Self ◽  
Nitrate Ion ◽  
Self Diffusion

Self-Diffusion of Sodium, Chloride and Iodide Ions in Methanol-Water Mixture

1986 ◽  
Vol 41 (7) ◽  
pp. 939-943 ◽  
Author(s):  
E. Hawlicka
Keyword(s):  
Sodium Chloride ◽  
Diffusion Coefficients ◽  
Solvent Composition ◽  
The Self ◽  
Water Mixture ◽  
Preferential Hydration ◽  
Water Solutions ◽  
Iodide Ions ◽  
Self Diffusion

The self-diffusion coefficients of Na+, Cl- and I- in methanol-water solutions at 35 ± 0.01 °C have been measured in their dependence on the salt molarity in the range 1 · 10-4- 1 · 10-2 mol dm -3. The ionic self-diffusion coefficients in infinitely diluted solutions have been computed. The influence of the solvent composition on the solvation of the ions is discussed. A preferential hydration of Na+, Cl- and I- ions in water-methanol mixtures has been found.

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