EFFECT OF IONIC AND NONIONIC SUBSTITUENTS ON THE ELECTRORHEOLOGICAL CHARACTERISTICS OF POLYANILINE DERIVATIVES

2001 ◽  
Vol 15 (06n07) ◽  
pp. 988-995 ◽  
Author(s):  
H. J. CHOI ◽  
M. S. CHO ◽  
J. W. KIM ◽  
R. M. WEBBER ◽  
M. S. JHON
Keyword(s):  
Silicone Oil ◽  
Experimental Results ◽  
Dielectric Spectra ◽  
Er Fluids ◽  
Ionic Copolymer ◽  
Poly Aniline

We report our experimental results on the electrorheological (ER) characteristics of ER fluids consisting of suspensions of semiconducting polyaniline and copolyaniline particles in silicone oil. Ionic sodium diphenylamine sulfonate and nonionic o-ethoxyaniline were introduced to synthesize copolyanilines, i.e. N-substituted copolyaniline and poly (aniline-co-o-ethoxyaniline), respectively. ER fluids using these particles were compared. ER fluids, which contain the ionic copolymer, showed the highest ER performance among polyaniline and its copolymer systems. This result was interpreted in terms of the conductivities of the particles and their dielectric spectra.

SYNTHESIS AND VISCOELASTIC BEHAVIORS OF POLY(ANILINE-CO-O-ETHOXYANILINE) PARTICLES SUSPENDED ELECTRORHEOLOGICAL FLUID

2001 ◽  
Vol 15 (06n07) ◽  
pp. 649-656 ◽  
Author(s):  
H. J. CHOI ◽  
J. W. KIM ◽  
M. S. SUH ◽  
M. J. SHIN ◽  
K. TO
Keyword(s):  
Particle Size ◽  
Silicone Oil ◽  
Loss Modulus ◽  
Chemical Oxidation ◽  
Steady Shear ◽  
Rheological Parameters ◽  
Linear Viscoelastic Region ◽  
Linear Viscoelastic ◽  
Er Fluids ◽  
Poly Aniline

Copolyanilines are synthesized by a chemical oxidation of aniline and o-ethoxyaniline with various molar ratios in an acidic media, and then characteristics of these polymers such as chemical structure, particle size and the particle size distribution were examined by using FT-IR, SEM and particle size analyzer, respectively. Suspensions of copolyaniline containing ethoxy group, namely poly(aniline-co-o-ethoxyaniline), in silicone oil have been investigated as one of many potential candidates for dry-base electrorheological (ER) fluid systems. Rotational rheometer (Physica) equipped with a high voltage generator was used to characterize the rheological properties of ER fluids from both steady shear and dynamic tests. From the steady shear experiment, we obtained flow properties and found that ER fluids exhibited the yield phenomenon. On the other hand, viscoelastic property was also obtained from the dynamic experiment. Since viscoelastic properties for ER fluids are mainly dominated by the particle chain structure, the state at different time scale was analyzed from the rheological parameters such as storage modulus (G'), loss modulus (G'') and tan δ. We conducted a strain amplitude sweep at 1 Hz under an applied electric field to determine a linear viscoelastic region first. The G' and G'' were then measured by a frequency sweep from 0.1 to 100 Hz in the linear viscoelastic region.

INFLUENCE OF SURFACTANTS ON PROPERTIES OF ELECTRORHEOLOGICAL FLUIDS CONTAINING POLYANILINE

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2461-2467 ◽  
Author(s):  
MAŁGORZATA BOCIŃSKA ◽  
HENRYK WYCIŚLIK ◽  
MARCIN OSUCHOWSKI ◽  
JANUSZ PŁOCHARSKI
Keyword(s):  
Yield Stress ◽  
Current Density ◽  
Silicone Oil ◽  
Flow Curves ◽  
Different Types ◽  
Order Of Magnitude ◽  
Dynamic Yield ◽  
Rate Of Sedimentation ◽  
Er Fluids

Sedimentation which is a natural process in most of ER fluids can be reduced by addition of surfactants that influence also other properties of the fluids. To study both the ER effect and the rate of sedimentation was the aim of the investigations. The ER fluids comprised powdered polyaniline and silicone oil to which surfactants of different polarity were added. The rate of sedimentation was measured by a sedimentation balance. The flow curves were recorded under electric field up to 2.5 kV/mm. Current density was also measured as a function of shear rate. It was found that the activity of a surfactant depends strongly on its polarity. The lipophylic surfactants stabilized the suspension very well but about 30% decrease of the dynamic yield stress was observed. The current density was reduced as well by almost one order of magnitude. The hydrophylic surfactants hardly stabilized the suspension but increase of yield stress was observed that was not followed by increase of current density. The role of different types of non-ionic surfactants was discussed.

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.

Physicochemical Aspects of Forming Electrorheological Fluids

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1739-1749
Author(s):  
E.V. Korobko
Keyword(s):  
Physical Model ◽  
Experimental Results ◽  
Electrorheological Fluids ◽  
Er Fluids

Based on the experimental results and physical representations fo ER-fluids as a "poor" dielectric, a physical model of the ER-effect is elaborated and the main approaches to creation of electrosensitive fluids with desired properties are determined.

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.

Experimental Research on the Heat Transfer Characteristics of Electrorheological Fluid Shock Absorber

2012 ◽  
Vol 594-597 ◽  
pp. 2836-2839
Author(s):  
Rui Wang ◽  
Yi Chun Wang ◽  
Chao Qing Feng ◽  
Fei Zhou
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Experimental Research ◽  
Ultrafine Particles ◽  
Shock Absorber ◽  
Silicone Oil ◽  
Electrorheological Fluid ◽  
Heat Transfer Characteristics ◽  
Electric Voltage ◽  
Er Fluids

Abstract：In order to study the thermal conductivity of ER in shock absorber, the AL2O3 and TiO2 ultrafine particles silicone oil ER are prepared to the different weights and been researched by experiment. Experiment result indicated: in the 5 mm scope of the electrode plank, the voltage from zero to three thousand, the thermal conductivity of ER fluids go up linear with the voltage growing, but the range is smaller; from three thousand to four thousand and five hundred voltage, the thermal conductivity of ER fluids go up with the voltage quickly. Under the high electric voltage, the ultrafine particles are polarized, the plus and minus particles are drawn each other, the particles are put in order and increasing the thermal conductivity.

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.

Influence of SiO2 Particles on the Defoaming Performance of Silicone Oil Emulsion

2013 ◽  
Vol 455 ◽  
pp. 39-42
Author(s):  
Chen Chen ◽  
Zhi Rong Ren ◽  
Yong Jun He
Keyword(s):  
Silicone Oil ◽  
Experimental Results ◽  
Oil Emulsion ◽  
Different Diameters

The defoaming agent of silicone oil emulsion containing hydrophobic SiO2particles was prepared. The effect of different diameters of SiO2particles and amount of SiO2particles in the emulsion on the defoaming performance was studied, and the mechanism of defoaming was analyzed. The experimental results showed that when the amount of hydrophobic SiO2particles in the emulsion was 1%, the emulsion had good defoaming performance; The emulsion containing nanometer sized SiO2particles showed better defoaming performance than that of the emulsion containing micrometer sized SiO2particles.

Effect of Particle Size and Distribution on the Viscosity of a Model Electrorheological (ER) Fluid

1999 ◽  
Author(s):  
Ying Chen ◽  
Hans Conrad
Keyword(s):  
Particle Size ◽  
Reasonable Agreement ◽  
Volume Fraction ◽  
Silicone Oil ◽  
Zero Field ◽  
Effect Of Particle Size ◽  
Er Fluids ◽  
Er Fluid ◽  
Modified Equation ◽  
Single Size

Abstract The zero-field viscosity of model ER fluids consisting of glass beads in silicone oil was determined as a function of average particles size (D¯ = 3–75 μm), volume fraction (ϕ = 0.1–0.3) and bimodal mixtures of two sizes. The viscosity increased with ϕ and decreased with D¯. The viscosity of the suspensions ηs in all cases was described reasonably well by the following relation:ηs=ηs,o(ϕ)+b(ϕ)D¯2/D¯3 where ηs,o(ϕ) and b(ϕ) are constants which increase with ϕ. Reasonable agreement with the Mooney crowding equation occurred for the single size particles, giving for the crowding factor k = 1.3 + 1.5/D¯. For ϕ < 0.2 the viscosity of the bimodal mixtures could be described by a modification of the Mooney equationηsηo=exp(2.76ϕ11-k1ϕ1)exp(2.76ϕ21-k2ϕ2) where ηo is the viscosity of the silicone oil, ϕi the volume fraction of each particle size Di and ki the normal crowding factor for that size. At ϕ = 0.3 the measured values of ηs for the bimodal mixtures became appreciably larger than those calculated from the modified equation. The decrease in particle size leads to both an increase in surface area of the particles per unit volume of the suspension and to a decrease in spacing (crowding); both factors probably contributed to the increase in ηs.

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