Dependence of the shear stress on particle properties in electrorheological fluids

2001 ◽  
Vol 15 (06n07) ◽  
pp. 938-946 ◽  
Author(s):  
Kunquan Lu ◽  
Yucheng Lan ◽  
Shouqiang Men ◽  
Xiaoyu Xu ◽  
Zhao Xianpeng ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Shear Stress ◽  
Silicone Oil ◽  
Theoretical Calculations ◽  
Ferroelectric Material ◽  
Electrorheological Fluids ◽  
Particle Properties ◽  
Er Fluids ◽  
Er Fluid ◽  
Curie Temperature Tc

By measuring the shear stress of a ferroelectric particle/silicone oil ER fluid varying with the temperature across Tc, the dependence of ER effect on permittivity mismatch is quantitatively obtained. The dielectric property of ferroelectric material behaves a dramatic change at Curie temperature (Tc) either in the dielectric constant and the conductivity. TGS and KNO 3 ferroelectric particles are chosen for studying the dielectric constant and conductivity dependence of the shear stress in ER fluids respectively. The measured results are more reliable, because the conditions, such as size, shape, composition of particles, especially chemical nature of particles and interface property between particles and liquid, all are same. The available theoretical calculations can not well fit our measured results. In order to consider the properties of whole suspensions, the orientation of the particles with spontaneous polarization under an electric field was studied in advance.

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.

Sound Transmission Loss in Electrorheological Fluids Under DC Voltage

2000 ◽  
Author(s):  
Marek L. Szary ◽  
Maciej Noras
Keyword(s):  
Shear Stress ◽  
Sound Pressure ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Electrorheological Fluids ◽  
Sound Transmission Loss ◽  
Dc Voltage ◽  
College Of Engineering ◽  
Er Fluids ◽  
Er Fluid

Abstract Extensive investigations of sound transmission loss (STL) in electrorheological (ER) fluids were conducted in the Acoustics Laboratory in the College of Engineering, Southern Illinois University Carbondale. The STL was investigated for different kinds of ER suspensions in frequency ranges from 100 Hz to 2kHz. Applied DC voltage to the different electrodes allowed normal and shear stress to develop in the ER fluid respectively. The electric field density was variable. Sound transmission loss was obtained by measurement of the sound pressure level in front of and behind the sample. Under both normal and shear stress in ER fluid, STL decreases with increasing stress. Those properties of ER fluids can be useful in noise and vibration control applications.

THE CONDUCTIVITY AND TEMPERATURE DEPENDENCE OF BATIO3 COATED- PAN BASED ELECTRORHEOLOGICAL FLUIDS

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1423-1429 ◽  
Author(s):  
J. H. WEI ◽  
J. SHI ◽  
Z. Y. LIU ◽  
J. G. GUAN ◽  
R. Z. YUAN
Keyword(s):  
Shear Stress ◽  
Barium Titanate ◽  
Silicone Oil ◽  
Sol Gel ◽  
Temperature Stability ◽  
Electrorheological Fluids ◽  
Environment Temperature ◽  
Er Fluids ◽  
Favorable Temperature ◽  
Gel Processing

Coated-PAn particles consisting of polyaniline(PAn) core and barium titanate ( BaTiO 3) shell were synthesized by modified sol-gel processing. The shear stress and current density of the suspensions of Coated-PAn particles and pure PAn particles in silicone oil with a 20vol% were investigated at different conductivity and environment temperature. The dielectric and the conductance behavior of coated PAn particles as a function of temperature we also investigated. The results showed that the ER effect of BaTiO 3 coated PAn particles was far stronger than that of pure polyaniline synthesized by the same method. Meanwhile, the BaTiO 3 coated-PAn particles also showed favorable temperature stability and low current loss at the high electric field, which is rather important for the ER fluids application.

Coating of Polyaniline with an Insulating Polymer to Improve the Power Efficiency of Electrorheological Fluids

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1931-1939 ◽  
Author(s):  
J. Akhavan ◽  
K. Slack ◽  
V. Wise ◽  
H. Block
Keyword(s):  
Power Efficiency ◽  
Electrorheological Fluids ◽  
Emeraldine Base ◽  
Heavy Duty ◽  
Base Form ◽  
Static Yield ◽  
High Fields ◽  
Er Fluids ◽  
Er Fluid ◽  
A Current

Currents drawn under high fields often present practical limitations to electrorheological (ER) fluids usefulness. For heavy-duty applications where large torques have to be transmitted, the power consumption of a ER fluid can be considerable, and for such uses a current density of ~100μ A cm -2 is often taken as a practical upper limit. This investigation was conducted into designing a fluid which has little extraneous conductance and therefore would demand less current. Selected semi-conducting polymers provide effective substrates for ER fluids. Such polymers are soft insoluble powdery materials with densities similar to dispersing agents used in ER formulations. Polyaniline is a semi-conducting polymer and can be used as an effective ER substrate in its emeraldine base form. In order to provide an effective ER fluid which requires less current polyaniline was coated with an insulating polymer. The conditions for coating was established for lauryl and methyl methacrylate. Results from static yield measurements indicate that ER fluids containing coated polyaniline required less current than uncoated polyaniline i.e. 0.5μ A cm -2. The generic type of coating was also found to be important.

LANTHANUM TITANATE NANOPARTICLES ER FLUIDS WITH HIGH PERFORMANCE

2012 ◽  
Vol 26 (13) ◽  
pp. 1250079 ◽  
Author(s):  
DE WANG ◽  
RONG SHEN ◽  
SHIQIANG WEI ◽  
KUNQUAN LU
Keyword(s):  
Yield Stress ◽  
Silicone Oil ◽  
Heating Temperature ◽  
Hydroxyl Group ◽  
Lanthanum Titanate ◽  
Different Temperatures ◽  
Static Yield ◽  
Er Fluids ◽  
Er Fluid ◽  
Static Yield Stress

A new type of electrorheological (ER) fluid consisting of lanthanum titanate (LTO) nanoparticles is developed. The ER fluids were prepared by suspending LTO powder in silicone oil and the particles were fabricated by wet chemical method. This ER fluid shows excellent ER properties: The static yield stress reaches over 150 kPa under 5 kV/mm with linear dependence on the applied DC electric field, and the current density is below 10 μA/cm2. In order to investigate the affect factor on the ER behavior, the LTO powder were heated under different temperatures. The ER performances of two particles treated under different temperatures were compared and the composition changes for those particles were analyzed with TG-FTIR technique. It was found that the static yield stress of the suspensions fell from over 150 kPa to about 40 kPa and the current densities decreased prominently as the rise of the heating temperature. TG-FTIR analysis indicated that polar groups remained in the particles such as alkyl group, hydroxyl group and carbonyl group etc., contribute to the ER effect significantly. The experimental results are helpful to understand the mechanism of the high ER effect and to synthesize better ER materials.

ELECTRORHEOLOGICAL EFFECT OF CONDUCTIVE POLYMERS DISPERSED IN LIQUID CRYSTALLINE MATRIX

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1135-1141 ◽  
Author(s):  
MONIKA CISZEWSKA ◽  
JANUSZ PLOCHARSKI
Keyword(s):  
Liquid Crystalline ◽  
Silicone Oil ◽  
Crystalline Polymer ◽  
Electrorheological Fluids ◽  
Flow Curves ◽  
Homogeneous Solutions ◽  
Electrorheological Effect ◽  
Active Liquid ◽  
Er Fluids ◽  
Crystalline Matrix

Hybrid electrorheological fluids comprising powdered conjugated polymers dispersed in solutions of a liquid crystalline polymer were prepared and studied. FeCl 3 doped poly(p-phenylene) and pyrolised polyacrylonitrile were chosen as the dispersed phase and poly(n-hexyl isocyanate) dissolved in xylene was used as the active liquid matrix. All the component materials were extensively characterized by various methods. Flow curves of the hybrid ER fluids were recorded under electric field and compared with analogous curves obtained for dispersions of the powders in silicone oil and with homogeneous solutions of the LC polymer in xylene. A very significant enhancement of the ER effect in the studied hybrid fluids was observed.

HIGH PERFORMANCE CALCIUM TITANATE NANOPARTICLE ER FLUIDS

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1110-1113 ◽  
Author(s):  
XUEZHAO WANG ◽  
RONG SHEN ◽  
WEIJIA WEN ◽  
KUNQUAN LU
Keyword(s):  
High Performance ◽  
Silicone Oil ◽  
Calcium Titanate ◽  
Hydroxyl Group ◽  
Long Term Stability ◽  
Dc Electric Field ◽  
Wet Chemical ◽  
Er Fluids ◽  
Er Fluid

A type of calcium titanate (CTO) nanoparticles was synthesized by means of wet chemical method [1] without coating on the particles. The CTO/silicone oil ER fluid exhibits excellent electrorheological properties: high shear stress (~50-100 kPa ) under dc electric field, a low current density (less than 2μA/cm2 at 5kV/mm), and long term stability against sedimentation. Although there are not special additives in the ER fluids, it is found from the chemical analysis that a trace of alkyl group, hydroxyl group, carbonyl group and some ions is remained in the particles which may dominate the ER response.

Electrorheological Properties of Suspensions Based on Polyaniline-montmorillonite Clay Nanocomposite

2002 ◽  
Vol 17 (6) ◽  
pp. 1513-1519 ◽  
Author(s):  
Jun Lu ◽  
Xiaopeng Zhao
Keyword(s):  
Dielectric Constant ◽  
Dielectric Loss ◽  
Yield Stress ◽  
Electric Fields ◽  
High Dielectric Constant ◽  
Silicone Oil ◽  
Transmission Electron ◽  
High Dielectric ◽  
Er Fluid ◽  
Electrorheological Properties

It is thought that high-dielectric constant, suitable conductivity, and dielectric loss dominate electrorheological (ER) effects. According to this viewpoint, the polyaniline/montmorillonite nanocomposite (PANI-MMT) particles with high-dielectric constant and suitable conductivity were synthesized by an emulsion intercalation method. The electrorheological properties of the suspensions of PANI-MMT particles in silicone oil have been investigated under direct current electric fields. At room temperature, it was found that the yield stress of PANI-MMT ER fluid was 7.19 kPa in 3 kV/mm, which is much higher than that of pure polyaniline (PANI), that of pure montmorillonite (MMT) as well as that of the mixture of polyaniline with clay (PANI+MMT). In the range of 10–100 °C, the yield stress changed only 6.5% with the variation of temperature. The sedimentation ratio of PANI-MMT ERF was about 98% after 60 days. The structure of PANI-MMT particles was characterized by infrared, x-ray diffraction (XRD), and transmission electron microscopy (TEM) spectrometry, respectively. The XRD spectra show that the inner layer distance of PANI-MMT can be enhanced to 1.52 nm when the PANI was inserted into the interlayer of MMT, whereas it is only 0.96 nm for free MMT. TEM shows that the diameter of PANI-MMT particles is about 100 nm. The dielectric constant of PANI-MMT nanocomposite was increased 5.5 times that of PANI and 2.7 times that of MMT, besides, the conductivity of PANI-MMT particle was increased about 8.5 times that of PANI at 1000 Hz. Meanwhile, the dielectric loss tangent can also be increased about 1.7 times that of PANI. It is apparent that the notable ER effect of PANI-MMT ER fluid was attributed to the prominent dielectric property of the polyaniline-montmorillonite nanocomposite particles.

Review of the Electrorheological (Er) Effect of Polyurethane-based Er Fluids

2008 ◽  
Vol 18 (2) ◽  
pp. 23956-1-23956-8 ◽  
Author(s):  
S. Schneider ◽  
S. Eibl
Keyword(s):  
Silicone Oil ◽  
Molecular Size ◽  
Electrorheological Fluids ◽  
Chemical Analyses ◽  
Temperature Dependent ◽  
Polarization Model ◽  
Basic Principles ◽  
Dependent Behavior ◽  
Er Fluids ◽  
Temperature Dependent Behavior

Abstract Electrorheological fluids (ERF) change viscosity when an electric field is applied. A special type of ERF consists of polyurethane particles which are doped with Li+ and /or Zn2+ cations and suspended in silicone oil. This article gives an overview of the temperature dependent behavior of the ER effect for these fluids and describes the basic principles how this is explained. Chemical analyses provide information as a basis for a polarization model in several dimensions down to molecular size.

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