scholarly journals RESEARCH THERMODYNAMICS OF VISCOUS FLOW OF BASE OILS THAT ARE THE BASIS FOR LUBRICANT COMPOSITIONS

2020 ◽  
pp. 89-93
Author(s):  
I. A. Novakov ◽  
F. S. Radchenko ◽  
A. S. Ozerin ◽  
A. S. Chevtaev ◽  
O. A. Krotikova
Keyword(s):  
Activation Energy ◽  
Viscous Flow ◽  
Thermodynamic Data ◽  
Thermodynamic Characteristics ◽  
Activation Entropy ◽  
Trade Marks ◽  
Lubricating Oils ◽  
Mineral Oils ◽  
Synthetic Oil ◽  
Mineral Base

The thermodynamic characteristics of the process of viscous flow of mineral base lubricating oils (SGK grade AU, naphthenic T-110) and synthetic (Synfluid PAO 6 cSt) were found. It was found that the activation energy and the change in the activation entropy of the viscous flow of mineral oils, considered trade marks, are higher than that of synthetic oil. The obtained thermodynamic data made it possible to establish the mechanism of the flow of lubricating oils.

scholarly journals Dynamic viscosity dependence on temperature for fuels used for diesel engine

2021 ◽  
Vol 32 (1) ◽  
pp. 98-103
Author(s):  
Irina Niţă ◽  
Sibel Osman ◽  
Olga Iulian
Keyword(s):  
Activation Energy ◽  
Diesel Engine ◽  
Viscous Flow ◽  
Dynamic Viscosity ◽  
Activation Parameters ◽  
Type Equation ◽  
Liquid Fuels ◽  
Activation Entropy ◽  
Different Temperatures ◽  
Viscosity Dependence

Abstract Viscosity is an important property of fuels used for diesel engine affecting engine’s efficiency and harmful gases emission. Viscosity of liquid fuels depends especially on fuels composition and temperature. The dynamic viscosity of diesel fuel, biodiesel and blends of diesel with biodiesel, i-propanol and n-butanol was measured for temperature ranging from 293.15 K to 323.15 K and atmospheric pressure. It has been verified that well-known Arrhenius derived equations can be used to estimate with good accuracy, viscosity at different temperatures for diesel, biodiesel, diesel+biodiesel blends, but also for diesel blends with propanol and butanol. Values of activation parameters: activation energy, activation enthalpy and activation entropy for the viscous flow were derived based on linearized Eyring’s type equation. The values of the activation energy for viscous flow of fuels and fuels blends calculated based on measured values of dynamic viscosity in the temperature range of 273.15 K and 323.15 K were similar to those presented in the literature for some hydrocarbons, esters, and alcohols, respectively.

ENTROPY INFLUENCE ON THE DEPENDENCE OF THE NANOFLUIDS VISCOSITY ON TEMPERATURE AND SHEAR RATE

2021 ◽  
Vol 7 (3) ◽  
pp. 89-105
Author(s):  
Lyudmila P. SEMIKHINA ◽  
Daniil D. Korovin
Keyword(s):  
Activation Energy ◽  
Shear Stress ◽  
Shear Rate ◽  
Viscous Flow ◽  
High Reliability ◽  
Narrow Particle Size Distribution ◽  
Disperse Systems ◽  
Rotational Viscometer ◽  
Surfactant Micelles ◽  
Dispersed Systems

A Brookfield DV-II + Pro rotational viscometer was used to study the viscosity of 7 samples of concentrated nanodispersed systems (nanofluids) with a similar viscosity (6-22 mPa ∙ s), the particles of the dispersed phase in which are nanosized surfactant micelles and conglomerates from them. It was found that for 5 out of 7 studied reagents, there is a decrease in viscosity typical for dispersed systems with an increase in the shear rate, and their flow curves, that is, the dependence of the shear stress on the shear rate, correspond to the ideal plastic flow of non-Newtonian fluids. Moreover, with high reliability, R2 ≥ 0.999 is described by the Bingham equation with a small value of the limiting shear stress (less than 0.2 Pa). It is shown that all the studied reagents are also characterized by an increase in the activation energy of a viscous flow Е with an increase in the shear rate. As a result, a decrease in viscosity with an increase in shear rate, typical for disperse systems, including nanofluids, is provided by a more significant increase in entropy changes ΔS compared to Е. It has been substantiated that, depending on the ratio between the activation energy of viscous flow Е and the change in entropy ΔS, the viscosity of concentrated micellar dispersed systems with an increase in the shear rate can decrease, remain unchanged, and increase. The last two cases, not typical for disperse systems and nanofluids, were identified and studied using the example of two demulsifiers, RIK-1 and RIK-2, with a maximum of a very narrow particle size distribution at 160 ± 5 nm, corresponding to the size of a special type of very stable micelles Surfactant — vesicle.

scholarly journals The use of differential calculation methods for the destruction of copolymers of polyethylene glycol fumarate with the acrylic acid

2020 ◽  
Vol 99 (3) ◽  
pp. 4-10
Author(s):  
M.Zh. Burkeev ◽  
◽  
A.Zh. Sarsenbekova ◽  
A.N. Bolatbay ◽  
E.M. Tazhbaev ◽  
...  
Keyword(s):  
Activation Energy ◽  
Polyethylene Glycol ◽  
Acrylic Acid ◽  
Polyester Resin ◽  
Thermodynamic Characteristics ◽  
Nitrogen Atmosphere ◽  
Inert Medium ◽  
Good Convergence ◽  
Sample Decomposition ◽  
First Time

In this work, the thermal decomposition of copolymers based on polyethylene glycol fumarate with the acrylic acid using various ratios of initial monomers has been studied for the first time. The samples were studied in air and nitrogen. According to the thermograms analysis, it was found that the copolymer sample decomposition begins at higher temperatures for a copolymer with high content of polyester resin. The copolymer is vigorously oxidized by the oxygen when heated in air, and one can observe almost complete sample decomposition, whereas it decomposes with a residue of ~ 15% in an inert medium. The activation energies for copolymers with different compositions were estimated using the differential methods of Freeman-Carroll, Achar and Sharpe-Wentworth. The activation energy values found by the three methods demonstrated a good convergence. It was shown that, the activation energy values are higher (~ 200 kJ/mol in the inert medium, and ~ 95 kJ/mol in the oxygen atmosphere) for a copolymer with a lower composition of polyester resin, and the activation energy is ~180 and ~85 kJ/mol for a copolymer with a greater composition of p-EGF-AA. The copolymer is more thermostable in the nitrogen atmosphere according to the kinetic parameters. Additionally, there were determined the thermodynamic characteristics, such as the Gibbs energy (∆G) and the entropy (∆S). They also confirm the destruction process dependence on the components ratio in the synthesized copolymer.

scholarly journals Activation Volume of Lubricating Oils in Viscous Flow

1976 ◽  
Vol 18 (1) ◽  
pp. 9-13 ◽  
Author(s):  
Yasukatsu Tamai ◽  
Toshikazu Yoneda
Keyword(s):  
Viscous Flow ◽  
Activation Volume ◽  
Lubricating Oils

Viscosity Of Molten Rare Earth Metal Trichlorides I. Cecl3, Ndcl3, Smcl3, Dycl3 And Ercl3

2003 ◽  
Vol 58 (7-8) ◽  
pp. 457-463 ◽  
Author(s):  
A. Potapov ◽  
V. Khokhlov ◽  
Y. Satoa
Keyword(s):  
Activation Energy ◽  
Rare Earth ◽  
Viscous Flow ◽  
Rare Earth Metal ◽  
Dynamic Viscosity ◽  
Kinematic Viscosity ◽  
Arrhenius Equation ◽  
Earth Metal ◽  
Capillary Viscometer ◽  
Density Data

The kinematic viscosity of molten CeCl3, NdCl3, SmCl3, DyCl3 and ErCl3 has been measured by using a capillary viscometer. The dynamic viscosity was computed by using density data taken from the literature. The viscosity increases with going from CeCl3 to ErCl3. The activation energy of the viscous flow, calculated by the Arrhenius equation, rises in the same order.

scholarly journals Kinetic Processes in Amorphous Materials Revealed by Thermal Analysis: Application to Glassy Selenium

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2725 ◽  
Author(s):  
Málek ◽  
Svoboda
Keyword(s):  
Activation Energy ◽  
Crystal Growth ◽  
Viscous Flow ◽  
Structural Relaxation ◽  
Amorphous Materials ◽  
Supercooled Liquid ◽  
Thermomechanical Analysis ◽  
Growth Data ◽  
Scanning Calorimetry ◽  
Kinetic Processes

It is expected that viscous flow is affecting the kinetic processes in a supercooled liquid, such as the structural relaxation and the crystallization kinetics. These processes significantly influence the behavior of glass being prepared by quenching. In this paper, the activation energy of viscous flow is discussed with respect to the activation energy of crystal growth and the structural relaxation of glassy selenium. Differential scanning calorimetry (DSC), thermomechanical analysis (TMA) and hot-stage infrared microscopy were used. It is shown that the activation energy of structural relaxation corresponds to that of the viscous flow at the lowest value of the glass transition temperature obtained within the commonly achievable time scale. The temperature-dependent activation energy of crystal growth, data obtained by isothermal and non-isothermal DSC and TMA experiments, as well as direct microscopic measurements, follows nearly the same dependence as the activation energy of viscous flow, taking into account viscosity and crystal growth rate decoupling due to the departure from Stokes–Einstein behavior.

Precision measurements of the effect of implanted boron on silicon solid phase epitaxial regrowth

1988 ◽  
Vol 3 (2) ◽  
pp. 298-308 ◽  
Author(s):  
Won Woo Park ◽  
M. F. Becker ◽  
R. M. Walser
Keyword(s):  
Activation Energy ◽  
Critical Temperature ◽  
Solid Phase ◽  
Laser Interferometry ◽  
Thermal Fluctuations ◽  
Solubility Limit ◽  
Activation Entropy ◽  
Epitaxial Regrowth ◽  
Sample Technique ◽  
Differential Increase

The epitaxial recrystallization rates of self-ion amorphitized layers in silicon wafers with 〈100〉 substrate orientation were measured by in situ, high precision, isothermal cw laser interferometry. With this one-sample technique the changes produced by implanted boron impurity concentrations (NB) in the activation energy Ea and preexponential V0 of solid phase epitaxy were measured for concentrations in the range 5 × 1018 cm−3 < NB < 3 × 1020 cm−3 and for temperatures from 450 to 550°C. The differential changes in Ea produced were measured to within ± 23 meV when systematic errors were eliminated. Changes in activation energy and entropy [Ea and log (V0)] were found to be linearly correlated for all concentrations. This observation is consistent with the idea that electronically active impurities alter regrowth velocities by reducing the critical temperature for disordering at some of the interfacial sites at which elementary reconstructive processes are driven by thermal fluctuations. For small Nn, the critical temperature of the impurity-modified reconstruction is estimated at 1200K, approximately 200 K below the melting temperature of amorphous silicon. The Ea decreased exponentially with NB to a concentration Ninfl, larger than the estimated equilibrium solubility limit, where there was an inflection point in the V vs NB curve. The Ea increased for values of NB larger than Ninfl, showing that the differential increase in V for higher concentrations was due to a differential increase in the activation entropy. A change in the correlation between Ea and log (V0) at Ninfl indicated that larger NB produced an additional reduction of the critical temperature of the reconstruction. For small NB, the data support a simple Fermi level shifting model for the “electronic effect” of impurities on SPE (solid phase epitaxial) regrowth.

scholarly journals The Glass Transition Temperature and Temperature Dependence of Activation Energy of Viscous Flow of Ovalbumin

2016 ◽  
Vol 39 (1) ◽  
pp. 13-25
Author(s):  
Karol Monkos
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscous Flow ◽  
Solvent Interactions ◽  
Model Free ◽  
Free Volume Model ◽  
Wide Range ◽  
Different Temperatures

Abstract The paper presents the results of viscosity determinations on aqueous solutions of ovalbumin at a wide range of concentrations and at temperatures ranging from 5°C to 55°C. On the basis of these measurements and three models of viscosity for glass-forming liquids: Avramov’s model, free-volume model and power-law model, the activation energy of viscous flow for solutions and ovalbumin molecules, at different temperatures, was calculated. The obtained results show that activation energy monotonically decreases with increasing temperature both for solutions and ovalbumin molecules. The influence of the energy of translational heat motion, protein-protein and protein-solvent interactions, flexibility and hydrodynamic radius of ovalbumin on the rate of decrease in activation energy with temperature has been discussed. One of the parameters in the Avramov’s equation is the glass transition temperature Tg. It turns out that the Tg of ovalbumin solutions increases with increasing concentration. To obtain the glass transition temperature of the dry ovalbumin, a modified Gordon-Taylor equation is used. Thus determined the glass transition temperature for dry ovalbumin is equal to (231.8 ± 6.1) K.

Thermogravimetric Studies on Bimetallic Dithiocarbamate Complexes

1992 ◽  
Vol 47 (9) ◽  
pp. 1297-1299 ◽  
Author(s):  
G. S. Sodhi ◽  
J. Kaur
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Decomposition Reaction ◽  
Activation Entropy ◽  
Acid Base ◽  
Thermal Stabilities ◽  
Tg Studies ◽  
Thermogravimetric Studies ◽  
Soft Acid ◽  
Hsab Theory

Thermogravimetric (TG) studies have been carried out for some bimetallic dithiocarbamate complexes of the type ZnML4 and NiM′L′4 [M = Co(II), Cu(II); M′ = Zn(II), Hg(II); L = N-methylcyclohexyldithiocarbamate; L′ = N-ethylcyclohexyldithiocarbamate]. From TG curves, the order, apparent activation energy and apparent activation entropy for the thermal decomposition reaction have been calculated. The thermal stabilities have been correlated with the structures of the complexes on the basis of hard and soft acid base (HSAB) theory.

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