The Relative Viscosity of Concentrated Rubber  Suspensions and Viscoelastic Modulus of 3D Сross-Linked Elastomers Filled with Solid Particles

Abstract A viscometer is described for measuring the viscosity of a liquid immediately after an abrupt reduction of the shearing stress to a very low value. A hollow cylinder on a torsion suspension is immersed in the liquid contained in a narrow annular channel. The inner wall of the channel is rotatable with respect to the outer wall, and by this rotation the liquid is stirred or sheared. After the stirring is stopped, the viscosity is measured by recording photographically the rotation of the hollow cylinder, driven by a nearly constant torque applied through the torsion suspension. Measurements were made on a commercial compounded rubber latex containing 47.5 per cent of total solids. Immediately after stirring, the latex is a Newtonian liquid with a viscosity of 0.05 poise. Thereafter the viscosity increases at an initial rate and to an ultimate value, both of which decrease as the shearing stress for measuring the viscosity is increased. The steady viscosity is attained approximately in 10 seconds. The observed extremes in steady viscosity were 11 and 0.5 poise, corresponding to the shearing stresses 1.3 and 10.7 dynes per sq. cm. The experimental data are fitted approximately by theoretical curves based on these assumptions. All aggregates of solid particles are broken up by the stirring. During subsequent thixotropic recovery, loose aggregates are formed which contain considerable trapped water. The rate of aggregation follows Smoluchowski's theory of slow coagulation, but both the coagulation rate constant and the percentage volume of water in the coagulates vary with the applied shearing stress. The relative viscosity of the suspension of aggregates follows an empirical law based on Eilers' data on aqueous suspensions of bitumen spheres.

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Natural Convective Heat Transfer of Water-in-FC72 Nanoemulsion Fluids

ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer, Parts A and B ◽

10.1115/mnht2008-52351 ◽

2008 ◽

Author(s):

Zenghu Han ◽

Bao Yang

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Convective Heat Transfer ◽

Convective Heat ◽

Hydrodynamic Interaction ◽

Convective Heat Transfer Coefficient ◽

Relative Viscosity ◽

Solid Particles ◽

Water Loading

The use of SOLID-particles has long been a common way of increasing fluid thermal conductivity. In this paper, nanoemulsion fluids—dispersions of LIQUID-nanodroplets—are proposed. As an example, water-in-FC72 nanoemulsion fluids are developed, and their thermophysical properties and impact on natural convective heat transfer are investigated experimentally. A significant increase in thermal conductivity—up to 52% for 12vol% of water nanodroplets (or 7.1 wt%)—is observed in the fluids. The enhancement in conductivity and viscosity of the fluids is found to be nonlinear with water loading, indicating an important role of the hydrodynamic interaction and aggregation of nanodroplets. However, the relative viscosity is found to be about two times the relative conductivity if compared at the same water loading. The presence of water nanodroplets is found to systematically increase the natural convective heat transfer coefficient in these fluids, in contrast to the observation in several conventional nanofluids containing solid nanoparticles.

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Rheology of three-phase suspensions determined via dam-break experiments

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2021.0394 ◽

2021 ◽

Vol 477 (2254) ◽

Author(s):

Janine Birnbaum ◽

Einat Lev ◽

Ed W. Llewellin

Keyword(s):

Capillary Number ◽

Relative Viscosity ◽

Shear Thickening ◽

Dam Break ◽

Solid Particles ◽

Rheological Models ◽

Volcanic System ◽

Three Phase ◽

Inertial Regime

Three-phase suspensions, of liquid that suspends dispersed solid particles and gas bubbles, are common in both natural and industrial settings. Their rheology is poorly constrained, particularly for high total suspended fractions (≳0.5). We use a dam-break consistometer to characterize the rheology of suspensions of (Newtonian) corn syrup, plastic particles and CO 2 bubbles. The study is motivated by a desire to understand the rheology of magma and lava. Our experiments are scaled to the volcanic system: they are conducted in the non-Brownian, non-inertial regime; bubble capillary number is varied across unity; and bubble and particle fractions are 0 ≤ ϕ gas ≤ 0.82 and 0 ≤ ϕ solid ≤ 0.37, respectively. We measure flow-front velocity and invert for a Herschel–Bulkley rheology model as a function of ϕ gas , ϕ solid , and the capillary number. We find a stronger increase in relative viscosity with increasing ϕ gas in the low to intermediate capillary number regime than predicted by existing theory, and find both shear-thinning and shear-thickening effects, depending on the capillary number. We apply our model to the existing community code for lava flow emplacement, PyFLOWGO, and predict increased viscosity and decreased velocity compared with current rheological models, suggesting existing models may not adequately account for the role of bubbles in stiffening lavas.

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Calculation of settling velocity of small solid particles in stratified suspension flows

International Journal of Multiphase Flow ◽

10.1016/s0301-9322(97)88556-4 ◽

1996 ◽

Vol 22 ◽

pp. 145

Author(s):

Y Pyrkin

Keyword(s):

Settling Velocity ◽

Solid Particles ◽

Suspension Flows

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Abrasive wear of polymer/steel gear drives

Progress in Agricultural Engineering Sciences ◽

10.1556/progress.4.2008.1 ◽

2008 ◽

Vol 4 (1) ◽

pp. 1-26

Author(s):

Gábor Kalácska

Keyword(s):

Wear Resistance ◽

Abrasive Wear ◽

Material Selection ◽

Solid Particles ◽

Soil Types ◽

General View ◽

Modern Engineering ◽

Clean Environment ◽

Engineering Polymers ◽

Plastic Gears

Research was performed on the friction, wear and efficiency of plastic gears made of modern engineering polymers and their composites both in a clean environment (adhesive sliding surfaces) and in an environment contaminated with solid particles and dust (abrasive), with no lubrication at all. The purpose is to give a general view about the results of abrasive wear tests including seven soil types as abrasive media. At the first stage of the research silicious sand was applied between the meshing gears and the wear of plastic and steel gears was evaluated and analyzed from the point of different material properties (elongation at break, hardness, yield stress, modulus of elasticity) and its combinations. The different correlations between the experienced wear and material features are also introduced. At the second stage of the project the abrasive sand was replaced with different physical soil types. The abrasive wear of gears is plotted in the function of soil types. The results highlight on the considerable role of physical soil types on abrasive wear resistance and the conclusions contain the detailed wear resistance. The results offer a new tribology database for the operation and maintenance of agricultural machines with the opportunity of a better material selection according to the dominant soil type. This can finally result longer lifetime and higher reliability of wearing plastic/steel parts.

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