HYSTERESIS PHENOMENON IN FLOW-CURVES OF ER FLUIDS CONTAINING SULFONATED POLYMER PARTICLES

2001 ◽  
Vol 15 (06n07) ◽  
pp. 1070-1077 ◽  
Author(s):  
RYUJI AIZAWA ◽  
SHEILA L. VIEIRA ◽  
MASAMI NAKANO ◽  
YOSHINOBU ASAKO
Keyword(s):  
Shear Rate ◽  
Electric Field ◽  
Volume Fraction ◽  
Hysteresis Phenomenon ◽  
Polymer Particles ◽  
Concentric Cylinder ◽  
Flow Curves ◽  
Shear Rates ◽  
Dispersed Particles ◽  
Er Fluids

The ER fluids containing sulfonated polymer particles were continuously sheared at increasing and decreasing shear rates using a rotary concentric cylinder rheometer and the hysteresis in the up- and down-flow-curves were analyzed. The ER fluids show hysteresis of shear stress and current density. The up-curve (when shear rate increased) was located below the down-curve (when shear rate decreased). As the electric field increased, the area in the hysteresis curves increased. The hysteresis depended on the electric field strength, the time of the applied electric field, the volume fraction of particles and the water content of the particles. Hysteresis phenomenon was explained, based on the formation of agglomerations of dispersed particles in the ER fluid and on changes of the lamellar formations

DIFFERENCES IN STEADY CHARACTERISTICS AND RESPONSE TIME OF ERF ON ROTATIONAL FLOW BETWEEN ROTATING DISK AND CONCENTRIC CYLINDER

2001 ◽  
Vol 15 (06n07) ◽  
pp. 1050-1056 ◽  
Author(s):  
K. SHIMADA ◽  
H. NISHIDA ◽  
T. FUJITA
Keyword(s):  
Shear Rate ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Current Density ◽  
Rotating Disk ◽  
Settling Time ◽  
Rotational Flow ◽  
Concentric Cylinder ◽  
Constant Shear Rate

We made an experimental investigation of the steady characteristics of torque, current density, and response time of ERF on rotational flow of the disk and the concentric cylinder. We used smectite particles suspension ERF and D.C. electric field. We compared the steady shearstress, current density, and the rise and settling time of the concentric cylinder and with those of the rotating disk. Then we clarified the differences. At a larger electric field strength, the shear stress, yield stress, and apparent viscosity to a constant shear rate in the case of the rotating disk are larger than they are in the case of the rotating concentric cylinder. However, at a larger electric field strength, the current density to a constant shear rate in the case of the rotating disk is smaller than it is in the case of the rotating concentric cylinder. Rise time of torque in the case of the rotating disk is faster than it is in the case of the rotating concentric cylinder. However, rise time of current density in the case of the rotating disk is slower than it is in the case of the rotating concentric cylinder at a small electric field strength. On the other hand, the difference of settling time of torque and current density between the rotating disk and the rotating concentric cylinder is changed by the electric field strength and shear rate. The settling time of torque in the case of the rotating disk is faster than it is in the case of the rotating concentric cylinder at a large electric field strength and large shear rate. The settling time of current density in the case of the rotating disk is slower than it is in the case of rotating concentric cylinder at a small electric field strength. Based on these results, the rotating disk has an efficiency of obtained torque to given electric power greater than that of the rotating concentric cylinder.

scholarly journals PROCESSING ADDITIVES AND RHEOLOGICAL PROPERTIES OF MOLDED PHENOLIC PLASTICS

2019 ◽  
Vol 14 (1) ◽  
pp. 90-96
Author(s):  
P. V. Surikov ◽  
N. L. Shembel ◽  
A. A. Yurkin ◽  
A. V. Petrogradsky ◽  
V. D. Sevruk ◽  
...  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Phenolic Resin ◽  
Volume Fraction ◽  
Slip Flow ◽  
Capillary Wall ◽  
Flow Curves ◽  
Flow Through ◽  
Capillary Viscosimetry ◽  
Stress Flow

By the method of capillary viscosimetry, the melt flow curves of the molded phenolic resin and its compositions with lubricant, plasticizer and their mixture were obtained. It was shown that the size (diameter) of the capillary channel influences the dependence of the effective shear rate on the shear stress (flow curves) of the studied compositions. Such rheological behavior of the compositions during flow is associated with the effect of sliding along the surface of the capillary wall. According to the Mooney method, the dependences of the effective shear rate at given values of shear stress on the reciprocal of the capillary radius are plotted. The function of the slip velocity on the shear stress on the capillary wall is characterized in terms of the slip coefficient, which relates the shear stress on the capillary wall to the velocity of the composition along it. For the studied compositions, the total flow through the capillary was divided into volume fractions, one of which is associated with a shear flow; the other is determined by the slip effect. It has been shown that the introduction of both a lubricant and a plasticizer into the composition leads to an increase in the fluidity of the compositions. At the same time, adding of lubricant increases the volume fraction of the slip flow. The greatest effect of increasing the fluidity of the composition gives the use of complex modifying additives containing both lubricant and plasticizer.

Yield Stress of Emulsions and Suspensions as Measured in Steady Shearing and in Oscillations

2008 ◽  
Vol 18 (4) ◽  
pp. 44790-1-44790-8 ◽  
Author(s):  
I. Masalova ◽  
A.Ya. Malkin ◽  
R. Foudazi
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Yield Stress ◽  
Flow Curves ◽  
Dynamic Yield Stress ◽  
Shear Rates ◽  
Meaningful Material ◽  
Dynamic Yield ◽  
Steady Shearing ◽  
Concentrated Emulsions

Abstract The yield stresses of five samples (two highly concentrated emulsions, two Kaolin dispersions and mayonnaise) were determined in two ways. In one case, steady shear experiments were performed over a range of incrementally decreasing shear rates. The resulting flow curves, plotted as shear stress against shear rate, clearly showed the existence of a yield stress for each sample, the Herschel-Bulkley model being fitted to obtain values. In the second case, oscillatory amplitude sweeps were performed at three frequencies, and the “dynamic yield stress” was defined as the stress at which deviation from linearity occurred; this procedure has often been used to determine the yield stress of emulsions. It was found that the dynamic yield stress is frequency dependent, and cannot therefore be thought of as physically meaningful material property. At no frequency did the dynamic yield stress correlate with the yield stress obtained from the flow curves.

SHEARING EFFECTS ON THE ELECTRORHEOLOGICAL RESPONSE

2001 ◽  
Vol 15 (06n07) ◽  
pp. 930-937 ◽  
Author(s):  
K. TANAKA ◽  
S. HASHIMOTO ◽  
T. TAKENOUCHI ◽  
I. SUGIMOTO ◽  
A. KUBONO ◽  
...  
Keyword(s):  
Shear Rate ◽  
Electric Field ◽  
Transient Response ◽  
Stress Responses ◽  
Experimental Conditions ◽  
Transient Stress ◽  
Shear Rates ◽  
Lower Shear ◽  
Mason Number ◽  
The Individual

The steady and transient stress responses were investigated from lower shear rates to higher shear rates at a given strength of the electric field, and the individual experimental conditions were reduced to Mason number ( M n). The electro-rheological response was found in the region with higher M n of the order of 10, and the transient response became faster as the shear rate increased. These results show that the effect of chance of collision among the polarized particles would play an important role even in the region.

scholarly journals Characterization of velocity fluctuations and the transition from transient to steady state shear banding with and without pre-shear in a wormlike micelle solution under shear startup by Rheo-NMR

2020 ◽  
Vol 30 (1) ◽  
pp. 1-13
Author(s):  
Rehab N. Al-kaby ◽  
Sarah L. Codd ◽  
Joseph D. Seymour ◽  
Jennifer R. Brown
Keyword(s):  
Steady State ◽  
Shear Rate ◽  
Shear Band ◽  
Shear Banding ◽  
Velocity Profiles ◽  
Concentric Cylinder ◽  
Stress Plateau ◽  
Interface Position ◽  
Shear Rates ◽  
Micelle Solution

AbstractRheo-NMR velocimetry was used to study shear banding of a 6 wt.% cetylpyridinium chloride (CPCl) worm-like micelle solution under shear startup conditions with and without pre-shear. 1D velocity profiles across the fluid gap of a concentric cylinder Couette shear cell were measured every 1 s following shear startup for four different applied shear rates within the stress plateau. Fitting of the velocity profiles allowed calculation of the shear banding characteristics (shear rates in the high and low shear band, the interface position and apparent slip at the inner rotating wall) as the flow transitioned from transient to steady state regimes. Characteristic timescales to reach steady state were obtained and found to be similar for all shear banding characteristics. Timescales decreased with increasing applied shear rate. Large temporal fluctuations with time were also observed and Fourier transform of the time and velocity autocorrelation functions quantified the fluctuation frequencies. Frequencies corresponded to the elastically driven hydrodynamic instabilities, i.e. vortices, that are known to occur in the unstable high shear band and were dependent upon both applied shear rate and the pre-shear protocol.

scholarly journals Rheological and Prediction of melt viscosity flow curves for blend of Polycarbonate (PC) and Polyacrylonitrile butadiene styrene (ABS)

2019 ◽  
Vol 12 (6) ◽  
pp. 33-40
Author(s):  
Alsaeed Douaa ◽  
Deri Fawaz
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Temperature Dependence ◽  
Melt Viscosity ◽  
Flow Curves ◽  
Actual Measurement ◽  
Shear Rates ◽  
Different Temperatures ◽  
Experimental Validity ◽  
Butadiene Styrene

A knowledge of the variation of melt viscosity of thermoplastic polymers with both shear rate and temperature is of considerable importance to plastics engineers as well as to polymer rheologists. The Actual measurement of melt viscosity at large number of temperatures and shear rates is frequently a tedious and time-consuming task. The experimental validity for superimposing Log shear stress – Log shear rate curves at different temperatures along the log shear rate axis has been established for the mixture of (polycarbonate and polyacrylonitrile butadiene styrene). The temperature dependence of the resultant shift factors has been determined to predict viscosities as a function of temperature and shear rate is discussed

scholarly journals Macroscopic rheology of non-Brownian suspensions at high shear rates: the influence of solid volume fraction and non-Newtonian behaviour of the liquid phase

2021 ◽  
Author(s):  
Patrick Wilms ◽  
Jörg Hinrichs ◽  
Reinhard Kohlus
Keyword(s):  
Liquid Phase ◽  
Shear Rate ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Shear Thinning ◽  
High Shear ◽  
Rate Dependency ◽  
Shear Rates ◽  
Liquid Phases ◽  
High Shear Rates

AbstractModelling the macroscopic rheology of non-Brownian suspensions is complicated by the non-linear behaviour that originates from the interaction between solid particles and the liquid phase. In this contribution, a model is presented that describes suspension rheology as a function of solid volume fraction and shear rate dependency of both the liquid phase, as well as the suspension as a whole. It is experimentally validated using rotational rheometry ($$\varphi$$ φ ≤ 0.40) and capillary rheometry (0.55 ≤ $$\varphi$$ φ  ≤ 0.60) at shear rates > 50 s−1. A modified Krieger-Dougherty relation was used to describe the influence of solid volume fraction on the consistency coefficient, $$K$$ K , and was fitted to suspensions with a shear thinning liquid phase, i.e. having a flow index, $$n$$ n , of 0.50. With the calculated fit parameters, it was possible to predict the consistency coefficients of suspensions with a large variation in the shear rate dependency of the liquid phase ($$n$$ n = 0.20–1.00). With increasing solid volume fraction, the flow indices of the suspensions were found to decrease for Newtonian and mildly shear thinning liquid phases ($$n$$ n ≥0.50), whereas they were found to increase for strongly shear thinning liquid phases ($$n$$ n ≤0.27). It is hypothesized that this is related to interparticle friction and the relative contribution of friction forces to the viscosity of the suspension. The proposed model is a step towards the prediction of the flow curves of concentrated suspensions with non-Newtonian liquid phases at high shear rates.

scholarly journals Viscosity and Rheological Properties of Graphene Nanopowders Nanofluids

Entropy ◽  
2021 ◽  
Vol 23 (8) ◽  
pp. 979
Author(s):  
Abderrahim Bakak ◽  
Mohamed Lotfi ◽  
Rodolphe Heyd ◽  
Amine Ammar ◽  
Abdelaziz Koumina
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Dynamic Viscosity ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Heat Extraction ◽  
Rheological Characterization ◽  
Shear Rates ◽  
Rheological Measurements

The dynamic viscosity and rheological properties of two different non-aqueous graphene nano-plates-based nanofluids are experimentally investigated in this paper, focusing on the effects of solid volume fraction and shear rate. For each nanofluid, four solid volume fractions have been considered ranging from 0.1% to 1%. The rheological characterization of the suspensions was performed at 20 ∘C, with shear rates ranging from 10−1s−1 to 103s−1, using a cone-plate rheometer. The Carreau–Yasuda model has been successfully applied to fit most of the rheological measurements. Although it is very common to observe an increase of the viscosity with the solid volume fraction, we still found here that the addition of nanoparticles produces lubrication effects in some cases. Such a result could be very helpful in the domain of heat extraction applications. The dependence of dynamic viscosity with graphene volume fraction was analyzed using the model of Vallejo et al.

STRUCTURE-ENHANCED YIELD SHEAR STRESS IN ELECTRORHEOLOGICAL FLUIDS

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2622-2628 ◽  
Author(s):  
R. Tao ◽  
Y. C. Lan ◽  
X. Xu
Keyword(s):  
Shear Stress ◽  
Electric Field ◽  
Volume Fraction ◽  
New Technology ◽  
Industrial Applications ◽  
Moderate Pressure ◽  
Yield Shear Stress ◽  
Weak Points ◽  
Er Fluids ◽  
Enhanced Yield

A new technology, compression-assisted aggregation, is developed to enhance the strength of electrorheological (ER) fluids. The yield shear stress of ER fluids depends on the fluid microstructure. The unassisted electric-field induced ER structure mainly consists of single chains, whose weak points are at their ends. This new technology produces a structure consisting of robust thick columns with strong ends. As the weak points of the original ER structure are greatly enforced, the new structure makes ER fluids super-strong: At a moderate electric field and moderate pressure the yield shear stress of ER fluids at 35% volume fraction exceeds 100 kPa, well above any requirement for major industrial applications.

Sign in / Sign up

Export Citation Format

Share Document