Plastics. Polymers/resins in the liquid state or as emulsions or dispersions. Determination of viscosity using a rotational viscometer with defined shear rate

1994 ◽  
Keyword(s):  
Shear Rate ◽  
Liquid State ◽  
Rotational Viscometer

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.

Experimental determination of the kinematic viscosity of glycerol-water mixtures

1994 ◽  
Vol 444 (1922) ◽  
pp. 573-581 ◽  
Keyword(s):  
Experimental Determination ◽  
Liquid State ◽  
Mass Fraction ◽  
Kinematic Viscosity ◽  
Limited Data ◽  
Glycerol Water ◽  
Mass Fractions ◽  
Comparative Accuracy ◽  
Water Glycerol

We have measured the kinematic viscosity of glycerol-water mixtures, for glycerol mass fractions ranging from 0 to 1, in the temperature range 10-50 °C. The measurements were made by using a series of Ubbelohde viscometers. Apart from comprehensiveness and comparative accuracy the present measurements expose serious errors in the limited data that were earlier available on such mixtures. It is shown that all the data can be reasonably represented by the empirical correlation (In ν m - In ν w )/(In ν g - In ν w ) = x g [1 + (1 - x g ) { a + bx g + cx g 2 }], where ν w , v g and ν m are the kinematic viscosities of water, glycerol and the mixture respectively and x g is the mass fraction of glycerol in the mixture. The constants a, b and c are tabulated in the paper as functions of temperature. This correlation can now be used at a given temperature to tailor make a mixture of prescribed kinematic viscosity. While this paper is addressed, principally, to fluid dynamicists these results should be of interest to physicists studying the liquid state and physical chemists interested in mixtures.

scholarly journals Selected physical properties of liquid biofuels

2013 ◽  
Vol 59 (No. 4) ◽  
pp. 121-127
Author(s):  
P. Trávníček ◽  
M. Valach ◽  
Z. Hlaváčová ◽  
J. Mareček ◽  
T. Vítěz ◽  
...  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Methyl Ester ◽  
Physical Properties ◽  
Methyl Esters ◽  
Calorific Value ◽  
Diesel Oil ◽  
Rapeseed Methyl Ester ◽  
Control Samples

The goal of this study was the determination of basic physical properties such as density, calorific value and rheological properties of liquid biofuels. Biofuels on the base of bioethanol and rapeseed methyl ester were chosen. Following control samples were selected: diesel oil without admixture of methyl esters and commercially available diesel oils with small amount of methyl ester admixture (6.2 and 6.5%). Dynamic viscosities of individual samples were measured in the range from –10°C to 50°C. Then dependence of shear rate on shear stress was measured at temperatures –10, 0, 20 and 40°C. The most of samples showed the Newtonian behaviour. However, samples with high content of methyl esters or pure methyl esters showed thixotropy behaviour at the low temperature.

Processing a Brookfield Rotational Viscometer Measurement Results in the MATLAB

2020 ◽  
Vol 834 ◽  
pp. 82-89
Author(s):  
Evgenii Igorevich Kurkin ◽  
Vladislava Olegovna Chertykovtseva ◽  
Yaroslav Vyacheslavovich Zakhvatkin
Keyword(s):  
Experimental Data ◽  
Carbon Fibers ◽  
Power Law Model ◽  
Rotational Viscometer ◽  
Measurement Results ◽  
Automatic Capture ◽  
Type Power ◽  
Short Carbon ◽  
Good Agreement

The Brookfield_to_MATLAB and ViscosityApproximation codes for processing of experiments results for determination of viscosity on a rotational Brookfield DV3T viscometer is developed in the MATLAB. The codes allow to carry out automatic capture data, to calculate the shear rate for standard spindles RV-1 ... RV-7, to sort the measurement results on temperatures, to combine the experimental data and to determine the coefficients of the Andrade type power-law model. Paper describes experiment results on determination of viscosity of the epoxy binder reinforced by short carbon fibers. The coefficients of the viscosity model are determined by the linear regression coefficients. The obtained determination coefficient shows a good agreement of the model with the experimental data. The results are used for study various contents of a mass fraction of fibers: 0%, 5%, 10%, and 15%.

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