INTERMOLECULAR FORCES AND LIQUID STRUCTURE IN SOME METAL ALKOXIDES

1961 ◽  
Vol 39 (8) ◽  
pp. 1619-1624 ◽  
Author(s):  
D. C. Bradley ◽  
Calliope C. A. Prevedorou ◽  
W. Wardlaw
Keyword(s):  
Activation Energy ◽  
Free Energy ◽  
Viscous Flow ◽  
Liquid Structure ◽  
Intermolecular Forces ◽  
Metal Alkoxides ◽  
Temperature Range ◽  
Entropy Of Activation ◽  
Titanium Zirconium

The viscosities of some alkoxides of titanium, zirconium, cerium (IV), thorium, and tin (IV) have been measured in the temperature range 25–40 °C. The liquid structure in these compounds is discussed in terms of the activation energy, free energy, and entropy of activation for viscous flow, and the energies of cohesion and vaporization.

scholarly journals Density, Viscosity and Free Energy of Activation for Viscous Flow of Monoethanol Amine (1) + H2O (2) + CO2 (3) Mixtures

Fluids ◽  
2020 ◽  
Vol 5 (1) ◽  
pp. 13 ◽  
Author(s):  
Sumudu S. Karunarathne ◽  
Dag A. Eimer ◽  
Lars E. Øi
Keyword(s):  
Free Energy ◽  
Viscous Flow ◽  
Viscosity Model ◽  
Energy Of Activation ◽  
Rate Theory ◽  
Density Correlation ◽  
Temperature Range ◽  
Monoethanol Amine ◽  
Free Energy Of Activation ◽  
Mass Fractions

Densities and viscosities of aqueous monoethanol amine (MEA) and CO2-loaded aqueous MEA are highly relevant in engineering calculations to perform process design and simulations. Density and viscosity of the aqueous MEA were measured in the temperature range of 293.15 K to 363.15 K with MEA mass fractions ranging from 0.3 to 1.0. Densities of the aqueous MEA were fitted for a density correlation. Eyring’s viscosity model based on absolute rate theory was adopted to determine the excess free energy of activation for viscous flow of aqueous MEA mixtures and was correlated by a Redlich–Kister polynomial. Densities and viscosities of CO2-loaded MEA solutions were measured in the temperature range of 293.15 K to 353.15 K with MEA mass fractions of 0.3, 0.4 and 0.5. The density correlation used to correlate aqueous MEA was modified to fit CO2-loaded density data. The free energy of activation for viscous flow for CO2-loaded aqueous MEA solutions was determined by Eyring’s viscosity model and a correlation was proposed to represent free energy of activation for viscous flow and viscosity. This can be used to evaluate quantitative and qualitative properties in the MEA + H2O + CO2 mixture.

Viscosity Measurements for La-Al-Ni liquid Alloys by an Oscillating Crucible Method

1998 ◽  
Vol 554 ◽  
Author(s):  
Tohru Yamasaki ◽  
Tomohiro Tatibana ◽  
Yoshikiyo Ogino ◽  
Akihisa Inoue
Keyword(s):  
Activation Energy ◽  
Viscous Flow ◽  
Melting Temperature ◽  
Glass Forming Ability ◽  
Liquid Alloys ◽  
Temperature Range ◽  
Glass Forming ◽  
Ni Alloys ◽  
Ni Content ◽  
Ni Alloy

AbstractThe viscosity of liquid lanthanum-based and aluminum-based La-Al-Ni alloys has been measured by an oscillating crucible method of the inverse suspending type in the temperature range from melting temperature (Tm) up to about 1400 K. In the case of La55Al45-xNix (x = 10∼40 at. %) alloys, the viscosity increased with increasing Ni content up to about 20 at. % Ni and then decreased with increasing the Ni content, while the activation energy for viscous flow decreased to a minimum value at about 20 at. % Ni. This composition is well consistent with that of the La-Al-Ni alloy having largest glass-forming ability.

Molecular association in liquids. III. A theory of cohesion of polar liquids

1952 ◽  
Vol 215 (1120) ◽  
pp. 67-83 ◽  
Keyword(s):  
Free Energy ◽  
Dipole Interaction ◽  
Liquid Structure ◽  
Intermolecular Forces ◽  
Cell Theory ◽  
Electrical Field ◽  
Polar Liquids ◽  
Lennard Jones ◽  
First Approximation ◽  
The Difference

This paper is an extension to polar liquids of the cell theory of liquid structure originally developed by Lennard-Jones & Devonshire. The free energy due to dipole interaction is evaluated using a model consisting of point dipoles fixed on the sites of a lattice but free to rotate in the electrical field of all the others. It is shown that, to a first approximation, the total free energy can be expressed as the sum of the free energy of this model and the free energy of a similar liquid without the dipole-dipole forces. The latter can be evaluated by the method of Lennard-Jones & Devonshire. The theory is applied to the polar liquids HCl, H 2 S and PH 3 . It is found that dipole interaction by itself is not sufficient to explain the difference between the cohesion of these liquids and similar non-polar liquids. The importance of other intermolecular forces between polar molecules is discussed.

Densities and kinematic viscosities of tetra-n-butylammonium iodide–nickel(II) chloride melts

1979 ◽  
Vol 57 (2) ◽  
pp. 147-150
Author(s):  
Nurul Islam ◽  
Abdul Maroof ◽  
Ismail Kochi
Keyword(s):  
Free Energy ◽  
Viscous Flow ◽  
Kinematic Viscosity ◽  
Composition Dependence ◽  
Energy Of Activation ◽  
Slight Tendency ◽  
Free Energy Of Activation ◽  
Chloride Melts ◽  
Entropy Of Activation ◽  
Viscous Behaviour

Densities and kinematic viscosities of molten mixtures of nickel(II) chloride in tetra-n-butylammonium iodide have been measured as functions of temperature and composition. The data on the kinematic viscosity have been analyzed using both Arrhenius and non-Arrhenius type equations. The heat of activation, the entropy of activation, and the free energy of activation for viscous flow have been computed. At higher concentrations a slight tendency towards non-Arrhenius viscous behaviour is observed. The free energy of activation helps in describing the overall composition dependence of kinematic viscosity.

Kinematic Viscosity and Electrical Resistivity of a Multicomponent Melt due to Liquid–Liquid Structure Transition

2021 ◽  
Vol 904 ◽  
pp. 111-116
Author(s):  
Vladimir Tsepelev ◽  
Yuri N. Starodubtsev ◽  
Viktor V. Konashkov ◽  
Yekaterina A. Kochetkova
Keyword(s):  
Activation Energy ◽  
Electrical Resistivity ◽  
Electrical Resistance ◽  
Cluster Size ◽  
Kinematic Viscosity ◽  
Arrhenius Plot ◽  
Liquid Structure ◽  
Structure Transition ◽  
Temperature Range ◽  
Temperature Dependences

We investigated the kinematic viscosity and electrical resistivity of the multicomponent Fe74Cu1Nb1.5Mo1.5B8.5Si13.5 melt during three heating–cooling cycles. The temperature dependence of kinematic viscosity and electrical resistivity have the anomalous zones in the same temperature range and they are associated with the liquid–liquid structure transition (LLST). The anomalies were explained by changes in the activation energy and the cluster size. As the cluster size decreases, the activation energy decreases, but the viscosity and electrical resistance increase. LLST begins with the cluster dissolution, and as a result, the Arrhenius plot becomes nonlinear in the transition temperature range. After three cycles of heating–cooling, the temperature dependences of the kinematic viscosity and electrical resistance did not qualitatively change, and this allows us to conclude that LLST is thermoreversible. With an increase in the number of thermal cycles, the activation energy of viscous flow decreases, as well as the onset temperature and temperature range of LLST.

scholarly journals Kinematic Viscosity ofMulticomponent FeCuNbSiB-BasedMelts

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1042
Author(s):  
Yuri N. Starodubtsev ◽  
Vladimir S. Tsepelev ◽  
Nadezhda P. Tsepeleva
Keyword(s):  
Activation Energy ◽  
Temperature Dependence ◽  
Viscous Flow ◽  
Cluster Size ◽  
Kinematic Viscosity ◽  
Cluster Structure ◽  
Liquid Structure ◽  
Logarithmic Scale ◽  
Structure Transition ◽  
Exponential Factor

The work investigated the temperature dependences of the kinematic viscosity for multicomponent melts of nanocrystalline soft magnetic alloys. It is shown that there is a linear relationship between the reduced activation energy of viscous flow Ea·(RT)−1 and the pre-exponential factor ν0. This ratio is universal for all quantities, the temperature dependence of which is expressed by the Arrhenius equation. It is shown that the activation energy of a viscous flow is linearly related to the cluster size on a natural logarithmic scale, and the melt viscosity increases with decreasing cluster size. The change in the Arrhenius plot in the anomalous zone on the temperature dependence of viscosity can be interpreted as a liquid–liquid structure transition, which begins with the disintegration of clusters and ends with the formation of a new cluster structure.

scholarly journals High-Temperature Deformation of Naturally Aged 7010 Aluminum Alloy

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 581
Author(s):  
Abdulhakim A. Almajid
Keyword(s):  
Activation Energy ◽  
Aluminum Alloy ◽  
High Temperature ◽  
Threshold Stress ◽  
Activation Energies ◽  
Temperature Deformation ◽  
High Temperature Range ◽  
Temperature Range ◽  
True Activation Energy ◽  
Two Temperatures

This study is focused on the deformation mechanism and behavior of naturally aged 7010 aluminum alloy at elevated temperatures. The specimens were naturally aged for 60 days to reach a saturated hardness state. High-temperature tensile tests for the naturally aged sample were conducted at different temperatures of 573, 623, 673, and 723 K at various strain rates ranging from 5 × 10−5 to 10−2 s−1. The dependency of stress on the strain rate showed a stress exponent, n, of ~6.5 for the low two temperatures and ~4.5 for the high two temperatures. The apparent activation energies of 290 and 165 kJ/mol are observed at the low, and high-temperature range, respectively. These values of activation energies are greater than those of solute/solvent self-diffusion. The stress exponents, n, and activation energy observed are rather high and this indicates the presence of threshold stress. This behavior occurred as a result of the dislocation interaction with the second phase particles that are existed in the alloy at the testing temperatures. The threshold stress decreases in an exponential manner as temperature increases. The true activation energy was computed by incorporating the threshold stress in the power-law relation between the stress and the strain. The magnitude of the true activation energy, Qt dropped to 234 and 102 kJ/mol at the low and high-temperature range, respectively. These values are close to that of diffusion of Zinc in Aluminum and diffusion of Magnesium in Aluminum, respectively. The Zener–Hollomon parameter for the alloy was developed as a function of effective stress. The data in each region (low and high-temperature region) coalescence in a segment line in each region.

scholarly journals Kinetics and thermodynamic properties related to the drying of 'Cabacinha' pepper fruits

2016 ◽  
Vol 20 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Hellismar W. da Silva ◽  
Renato S. Rodovalho ◽  
Marya F. Velasco ◽  
Camila F. Silva ◽  
Luís S. R. Vale
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Removal Rate ◽  
Effective Diffusion ◽  
Drying Time ◽  
Three Samples ◽  
Different Temperatures

ABSTRACT The objective of this study was to determine and model the drying kinetics of 'Cabacinha' pepper fruits at different temperatures of the drying air, as well as obtain the thermodynamic properties involved in the drying process of the product. Drying was carried out under controlled conductions of temperature (60, 70, 80, 90 and 100 °C) using three samples of 130 g of fruit, which were weighed periodically until constant mass. The experimental data were adjusted to different mathematical models often used in the representation of fruit drying. Effective diffusion coefficients, calculated from the mathematical model of liquid diffusion, were used to obtain activation energy, enthalpy, entropy and Gibbs free energy. The Midilli model showed the best fit to the experimental data of drying of 'Cabacinha' pepper fruits. The increase in drying temperature promoted an increase in water removal rate, effective diffusion coefficient and Gibbs free energy, besides a reduction in fruit drying time and in the values of entropy and enthalpy. The activation energy for the drying of pepper fruits was 36.09 kJ mol-1.

Sign in / Sign up

Export Citation Format

Share Document