ELECTRORHEOLOGY OF DISPERSIONS OF BaxSr(1-x)TiO3 IN SILICONE OIL UNDER AC OR DC ELECTRIC FIELD

2012 ◽  
Vol 26 (14) ◽  
pp. 1250081 ◽  
Author(s):  
GLAUBER M. S. LUZ ◽  
ANTONIO J. F. BOMBARD ◽  
SILVIO L. M. BRITO ◽  
DOUGLAS GOUVÊA ◽  
SHEILA L. VIEIRA
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Electric Field ◽  
Silicone Oil ◽  
Ferroelectric Materials ◽  
Dc Electric Field ◽  
Ac Fields ◽  
Er Fluid ◽  
Constant Shear Rate

Electrorheology (ER) of ferroelectric materials such as nanometric BaTiO 3 is still not fully understood. In this paper, nanoparticles of Ba x Sr (1-x) TiO 3 (where x = 0.8, 0.9 or 1.0) were synthesized using the method of Pechini, calcinated at 950°C, and after, lixiviated under pH 1 or pH 5. A controlled stress rheometer (MCR-301) was used to make the ER characterization of dispersions made of Ba x Ti 1-x O 3 in silicone oil (30% w/w), where (a) shear stress as a function of DC electric field (under constant shear rate) or (b) shear stress as a function of shear rate (under constant AC or DC electric field) were measured. We observed that electrophoresis occurred under electric field DC, creating a concentration gradient which induced phase separation in ER fluid. On the other hand, under AC fields above 1 kV/mm, the ER effect is stronger than for DC field, and almost without electrophoresis. Furthermore, there is an AC frequency, dependent on the disperse phase, where the ER effect has a maximum.

YIELD PROCESS OF ELECTRORHEOLOGICAL FLUID WITH POLYANILINE PARTICLE

1994 ◽  
Vol 08 (25) ◽  
pp. 1563-1575 ◽  
Author(s):  
KIYOHITO KOYAMA ◽  
KEIJI MINAGAWA ◽  
TAMOTSU YOSHIDA ◽  
NORIYUKI KURAMOTO ◽  
KATSUFUMI TANAKA
Keyword(s):  
Shear Stress ◽  
Electric Field ◽  
Particle Concentration ◽  
Silicone Oil ◽  
Electrorheological Fluid ◽  
Yield Behavior ◽  
Wide Range ◽  
Dc Electric Field ◽  
Er Fluid ◽  
Flow Experiments

Electrorheological behaviors of polyaniline/silicone oil suspension were observed by using a modified Couette type rheometer with high resolution for shear stress. The yield behaviors were examined over a wide range of shear strain. The storage modulus and loss tangent were determined under a constant dc electric field. It was clarified that the polyaniline-based ER fluid yields two different strain amplitudes, i.e. about 1% and 50%. The stress-strain curves obtained from shear flow experiments also suggested the existence of two-step yield process. The yield process was found to be dependent on the electric field strength and the particle concentration in different manners. The yield behavior observed is discussed in relation to the structure of particle clusters which causes the ER effect.

Measurement of Interaction Forces at Small Distance under Electric Field in a Smectite Dispersed Silicone Oil Based ER Fluid

2001 ◽  
Vol 15 (06n07) ◽  
pp. 811-816 ◽  
Author(s):  
Toyohisa FUJITA ◽  
Toshio MIYAZAKI ◽  
Toshiharu TANAKA ◽  
Ke Jun Liu ◽  
Eiich KUZUNO ◽  
...  
Keyword(s):  
Electric Field ◽  
Silicone Oil ◽  
Small Distance ◽  
Surface Forces ◽  
Attraction Force ◽  
Interaction Forces ◽  
Repulsive Energy ◽  
Inflection Points ◽  
Dc Electric Field ◽  
Er Fluid

The apparatus to measure interaction forces under an electric field at small distance between a conductive hemisphere and a flat plate has been developed. The surface forces at small distance sandwiched ER fluid dispersing ultrafine smectite particles (20 to 50 nm thickness) in silicone oil has been measured. This fluid shows 0.7 kPa of apparent yield stress by applying 2.5 kV/mm of DC electric field. When an electric field applies to this ER fluid, the repulsive energy curves shows inflection points at about 0.2 μ m distance periodically at small distance of less than 1 μ m because the repulsion force decreases for a vacancy of particles after the particles are pushed out and the dipole attraction force acts between hemisphere and plate. On the other hand, when the electric field becomes off and it passes enough time, the inflection points is observed more shorter distance of about 0.15 μ m periodically. The coagulated particle size is estimated about 0.15 μ m under no electric field and becomes larger by applying electric field.

ELECTRORHEOLOGICAL BEHAVIORS OF POLYANILINE-MONTMORILLONITE CLAY NANOCOMPOSITE

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2521-2527 ◽  
Author(s):  
JUN LU ◽  
XIAOPENG ZHAO
Keyword(s):  
Dielectric Constant ◽  
Shear Stress ◽  
Electric Fields ◽  
Room Temperature ◽  
Silicone Oil ◽  
Weight Fraction ◽  
Influential Factors ◽  
Dc Electric Field ◽  
Er Fluid ◽  
Xrd And Tem

Polyanilline-montmorillonite nanocomposite (PANI-MMT) particles were synthesized by an emulsion intercalation method and characterized by IR, XRD and TEM spectrometry. TEM showed that the particle's size of MMT-PANI particles was about 100 mm. The dielectric constant of PANI-MMT nanocomposite was increased 2.4 times than that of MMT and 7 times than PANI, the conductivity of PANI-MMT particles was increased was increased 10 times than that of MMT. Meanwhile, the dielectric loss tangent was also increased about 1.36 times than that of PANI. The electrorheological behaviors of the suspensions of PANI-MMT nanocomposite in silicone oil with a 30% weight fraction were investigated under DC electric fields. In 3 kV/mm DC field at room temperature, the yield stress was 8.26 kPa (shear 5 s -1). In 4 kV/mm DC field, the shear strength was 8.30 kPa (γ = 103.1 s -1, T = 20°C), and much higher than that of pure polyaniline (PANI), montmorillonite (MMT) and mixture of polyaniline with clay (MMT + PANI). The sedimentation experiment showed that the PANI-MMT nanocomposite particles did not deposit during about two months. The relevant influential factors between shear stress and electric fields, between shear stress and shear rate, between shear stress and temperature was also discussed preliminarily. The results showed that the MMT-PANI ER fluid displays a notable ER effect under DC electric field.

EFFECT OF RARE EARTH SUBSTITUTION ON ELECTRORHEOLOGICAL PROPERTIES OF TiO2

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2371-2377 ◽  
Author(s):  
X. P. ZHAO ◽  
J. B. YIN ◽  
L. Q. XIANG ◽  
Q. ZHAO
Keyword(s):  
Shear Stress ◽  
Rare Earth ◽  
Silicone Oil ◽  
Anatase Phase ◽  
New Class ◽  
Dc Electric Field ◽  
Er Fluids ◽  
Er Fluid ◽  
Electrorheological Properties ◽  
Rare Earth Substitution

This paper describes a new class of water-free electrorheological (ER) fluids based on nonaqueous doped TiO 2 with rare earth (RE) in silicone oil. The thermal character and crystal structure of these materials are investigated with DSC, TG and XRD. The doped TiO 2 crystals possess anatase phase and their lattice spacing varies significantly with the content of rare earth. The rheological measurements show that the doped TiO 2 ER fluid exhibits an obviously higher shear stress than that of pure TiO 2 ER fluid under dc electric field. Especially, substitution with 10mol% cerium or 8mol% lanthanum for Ti can obtain a relatively high shear stress. On the basis of dielectric and conduction measurements, we preliminarily discuss the influence of the doping of rare earth on ER effects of TiO 2.

ELECTRO-MAGNETORHEOLOGICAL FLUIDS DISPERSING ZEOLITE PARTICLES CONTAINING IRON

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2405-2411 ◽  
Author(s):  
A. SHIBAYAMA ◽  
T. MIYAZAKI ◽  
K. YAMAGUCHI ◽  
K. MURAKAMI ◽  
T. FUJITA
Keyword(s):  
Magnetic Field ◽  
Shear Stress ◽  
Shear Rate ◽  
Electric Field ◽  
Electric Fields ◽  
Fluid Viscosity ◽  
Magnetic Field Direction ◽  
Constant Shear ◽  
Stress Curve ◽  
Constant Shear Rate

Some functional fluids that respond to both magnetic and electric fields have been prepared and their characteristics are described. In this study, an electro-magnetorheological fluid (EMRF) dispersing zeolite particles containing metallic iron by reducing precipitated magnetite has been investigated. When the viscosity is measured by cone plate viscometer and cylindrical viscometer, electric and magnetic fields are applied both between cone and plate or two cylinders. In case of cone plate, the shear stress at constant shear rate increased with the increase of both magnetic field and electric field. On the other hand when the viscosity is measured by cylindrical viscometer, the shear stress at constant shear rate increased with the increase of electric field, however, the increase rate of shear stress by magnetic field is very small. In this case the magnetic field direction is perpendicular to electric field. The EMRF has typical characteristics to respond with magnetic and electric field. The shear stress of EMRF in electric field is stronger than that of magnetic field. Additionally, the inflection and peak point in the shear rate-shear stress curve are appeared and the behaviors of the clusters in the electric field are observed. The experimental results suggested that the fluid viscosity (shear stress/shear rate) is affected by the arrangement of clusters parallel or perpendicular to the direction of the EMRF flow.

TRANSIENT BEHAVIOR OF THE MICROSTRUCTURE OF ELECTRORHEOLOGICAL FLUIDS IN SHEAR FLOW MODE

2001 ◽  
Vol 15 (06n07) ◽  
pp. 695-703 ◽  
Author(s):  
S. L. VIEIRA ◽  
M. NAKANO ◽  
S. HENLEY ◽  
F. E. FILISKO ◽  
L. B. POMPEO NETO ◽  
...  
Keyword(s):  
Shear Stress ◽  
Shear Rate ◽  
Shear Flow ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Transient Behavior ◽  
Electrorheological Fluids ◽  
Flow Mode ◽  
Er Fluid

It was reported that under the simultaneous stimulus of an electric field and shear, the particles in an ER fluid form lamellar formations in the direction of shear (adhered to one of the electrodes) which may be responsible for the ER activity more than the strength of the chains. In this way, it would be expected that the shear stress should change consistently with the morphology of the formations. In this work we studied the effect of shearing time, electric field strength and shear rate on the shear stress. We suggest that changes on shear stress with time are due to changes of the morphology of the lamellar formations.

Breakups of an encapsulated surfactant-laden aqueous droplet under a DC electric field

Soft Matter ◽  
2019 ◽  
Vol 15 (43) ◽  
pp. 8905-8911 ◽  
Author(s):  
Muhammad Salman Abbasi ◽  
Ryungeun Song ◽  
Jinkee Lee
Keyword(s):  
Electric Field ◽  
Castor Oil ◽  
Silicone Oil ◽  
Double Emulsion ◽  
Emulsion Droplet ◽  
Dc Electric Field ◽  
Aqueous Droplet

We study the breakups of a surfactant-laden aqueous/silicone oil/castor oil double emulsion droplet under an electric field.

ER Properties of a Suspension of Polymer Graft Carbon Black Particles

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1682-1688
Author(s):  
Masayoshi Konishi ◽  
Teruhisa Nagashima ◽  
Yoshinobu Asako
Keyword(s):  
Shear Stress ◽  
Carbon Black ◽  
Electric Field ◽  
Silicone Oil ◽  
Average Particle Size ◽  
Average Particle ◽  
Zero Field ◽  
Average Value ◽  
Time Period ◽  
Micron Size

We newly developed ER particles with sub-micron size. The particle was polymer graft carbon black (GCB1) composed of carbon black particles and a polymer. The average particle size of GCB1 was found to be 81 nm. An ER suspension (ER1) was obtained by mixing GCB1 (30 wt%) with silicone oil (70 wt%). The ER1 showed excellent dispersion stability. Further, GCB1 particles did not settle under centrifuging at 9000G. The zero-field viscosity was 80 mPa·s at 25°C. The kinetic friction coefficient of ER1 was 0.15, while that of the silicone oil used was 0.23. When the electric field of 3 kV/mm (AC 1000 Hz) at the temperature of 25°C and the shear rate of 700 s -1 was applied to ER1, the shear stress of 116Pa was induced. The induced shear stress did not change for a long period of time period. In the temperature range between 25 and 150°C the induced shear stress and the current density were almost constant at any electric field. When 3 kV/mm (AC 50Hz) at 25°C and 700s-1 was applied to ER1, the shear stress of 88Pa was induced but the deviation of the induced shear stress from the average value was pluses and minuses 3 Pa.

scholarly journals Internal Damper Characteristics of Rotor System with Submerged ER Fluid Journal Bearing

1997 ◽  
Vol 3 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Siyoul Jang ◽  
John A. Tichy
Keyword(s):  
Shear Stress ◽  
Electric Field ◽  
Shear Strain ◽  
Yield Stress ◽  
Electric Fields ◽  
Journal Bearing ◽  
Shear Strain Rate ◽  
Newtonian Flow ◽  
Damping Coefficients ◽  
Er Fluid

Electro-Rheological (ER) fluid behavior is similar to Bingham fluid’ s. Only when the shear stress magnitude of ER fluid exceeds the yield stress, Newtonian flow results. Continuous shear strain rate equation about shear stress which simulates Bingham-like fluid shows viscosity variations. Shear yield stress is controlled by electric fields. Electric fields in circumferential direction around the journal are also changeable because of gap distance. These values make changes of spring and damping coefficients of journal bearings compared to Newtonian flow case. Implicit viscosity variation effects according to shear strain rates of fluid are included in generalized Reynolds' equation for submerged journal bearing. Fluid film pressure and perturbation pressures are solved using switch function of Elord's algorithm for cavitation boundary condition. Spring and damping coefficients are obtained for several parameters that determine the characteristics of ER fluids under a certain electric field. From these values stability region for simple rotor-bearing system is computed. It is found that there are no big differences in load capacities with the selected electric field parameters at low eccentric region and higher electric field can support more load with stability at low eccentric region.

Electroviscoelastic Properties in ER Gel of Disperse System under DC Electric Field

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2433-2439 ◽  
Author(s):  
R. HANAOKA ◽  
S. TAKATA ◽  
H. FUJITA ◽  
T. FUKAMI ◽  
K. SAKURAI ◽  
...  
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Disperse System ◽  
Fine Particles ◽  
Silicone Oil ◽  
Dynamic Properties ◽  
Low Frequencies ◽  
Hydrosilylation Reaction ◽  
Microscopical Method ◽  
Dc Electric Field

The silicone oil-based electrorheological (ER) gel containing the non-aqueous fine particles was newly created in the present study. After these particles were dispersed at 30wt.% in the dimethylsilicone oil, the ER gel was produced by the hydrosilylation reaction in the mixture of the modified silicone oil. The reaction could considerably be promoted by heating at 90°C. The behavior of particles in the ER gel was observed by a microscopical method. When an electric field was applied to the ER gel, the gap between the electrodes was bridged by the chains of particles arranged in the direction of the electric field. The dynamic properties of the ER gel were also examined under the applied dc electric field up to 2kV/mm using the oscillating rheometer with the low frequencies of 1Hz or less. Consequently, it is shown that the electroviscoelastic effect of the gel can be controlled by the electric field strength.

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