Design of anhydrous electrorheological (ER) suspensions based on I<sub>2</sub>‐doped poly(pyridinium salt)

Yu, Weiching; Shaw, Montgomery T.; Huang, Xiaoyan; Harris, Frank W.

doi:10.1002/polb.1994.090320309

Cited by 14 publications

(4 citation statements)

References 21 publications

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“…Of interest is that when Inoue (1990) added a so-called insulating film to the particle surfaces, the ER suspension of the insulated particles in silicone oil still showed a weak ER effect with dc applied field. However, Yu et al (1994) found that I 2 -doped polypyridinum salt particles with a socalled insulating skin gave a stronger ER effect, but a smaller current density, than the I 2 -doped polypyridinum salt particles (the conductivity of I 2 -doped polypyridinum salt core σ core = 10 −7 S m −1 and the conductivity of the skin σ skin ≤ 10 −12 S m −1 ). The effect of a surface insulating film on the ER effect is beyond the scope of the present paper but it is considered in detail in a forthcoming paper (Wu and Conrad 1997).…”

Section: Discussionmentioning

confidence: 94%

A modified conduction model for the electrorheological effect

Conrad

1996

J. Phys. D: Appl. Phys.

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A modified conduction model is proposed for predicting the maximum local electric field, current density and attractive force between two spherical particles in a host oil. The dependence of the conductivity of the host fluid on electric field is expressed by a simplified equation based on Onsager's theory. The model gives the ratio of the maximum local field to the applied field as , where and , A and are the conductivity parameters relating to the host fluid. is the conductivity of the particles and the applied field. Good agreement is found between the predicted and measured values of the current density and the yield stress of electrorheological (ER) suspensions. To obtain a strong ER effect, a high value of the combined conductivity parameter of the host fluid is desired.

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Section: Discussionmentioning

confidence: 94%

A modified conduction model for the electrorheological effect

Conrad

1996

J. Phys. D: Appl. Phys.

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“…Important in this theoretical consideration of the ER effect is to evaluate the value of ␤. Several authors have evaluated ␤ by assuming ⑀ r,p ӷ ⑀ r,oil leading to ␤ Ϸ 1 (31,32) or by measuring ⑀ r,p independently at a low electric field of several V/mm (33,34). However, it seems appropriate to evaluate ␤ with an application of shear and high electric field to the suspension, because of the dependence of the structuring on the experimental conditions.…”

Section: Figmentioning

confidence: 98%

Correlation between Generated Shear Stress and Generated Permittivity for the Electrorheological Response of Colloidal Silica Suspensions

Saimoto

Satoh

Konno

1999

Journal of Colloid and Interface Science

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“…In this case, we may consider that the adsorbed water of particles and the electric field play the same role in the ER effect as the time-temperature superposition principle in polymer science. Figure 5 shows the influence of the water content of Li-PMAA particles on current density of ER Figure 5 Influence of Q on current density for colloidal suspensions of Li-PMAA particles in poly(diethy1 siloxane) a t E of 2.1 kV/mm.…”

Section: 5mentioning

confidence: 99%

Direct synthesis of electrorheological suspension containing salt of poly(methacrylic acid) and its electrorheological effect

Xie

Guan

Guo

1995

J of Applied Polymer Sci

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SYNOPSISColloidal suspensions containing salts of poly(methacry1ic acid) which exhibit high electrorheological (ER) activity were synthesized by inverse emulsion polymerization. Factors influencing the ER effect were studied. The results showed that maximum yield stress occurred at optimum amounts of both polymeric stabilizer and crosslinking agent used in the inverse emulsion polymerization as well as a certain water content of the particles, while yield stress increased with electric field strength, average diameter of the particles below 0.9 pm, or the molar ratio of the salt to the acid. The ER activity for the suspensions containing different monovalent counter ions decreased in the following order: Li+ > Na+ > K+ > NH:. The phenomena were discussed with the ionic polarization mechanism. INTRODUCTIONElectrorheological ( ER) fluids, or suspensions, first discovered by Winslow, undergo dramatic changes in rheological properties such as development of a yield stress and increased viscosity upon application of kV/mm order of electric field. ER fluids, as a kind of smart material, may possibly be revolutionary in several areas of industry and technology because of their attractive features of rapid and reversible response to electric fields.2 From the early 1980s ER fluid has attracted the interest of many scientists and been developed as one "hot spot" in the research areas of material science and liquid physics. Now research on ER fluids mainly focuses on ( 1 ) influence of variables on ER effect and ER mechanism; ( 2 ) optimization of ER fluids formulas, especially synthesis of particles with high dielectric constants for high performance of ER fluids; and ( 3 ) exploitation of engineering application of ER fluids. Using polymers for dispersed particles in high performance ER fluids is becoming common due to * To whom correspondence should be addressed. their low density, high plasticity, and easy processibility into fine particle^.^-^ Suspension of the hydrated lithium polymethacrylate dispersed in a chlorinated paraffin oil has a high ER a~t i v i t y .~ Zukoski and c o -w o r k e r~~~~ extensively studied the influence of volume fraction and electric field strength on the dynamic ER properties and current density of the above suspension. Stangroom and obtained highly electrorheologically active suspensions by mixing chlorinated hydrocarbons, fluorolube FS, dipolar halogenated aromatics, or pentachlorophenyl phenyl ether with lithium polymethacrylate particles with adsorbed water, which were made by copolymerizing lithium methacrylate with divinyl benezene or methylene bisacrylamide (MBAM) in a 10% aqueous solution followed by complicate posttreatment. However, all these ER fluids have the crippling problem of poor stability. And poorly understood are the influences on ER effects of key variables such as particle size, molecular structure of particles, and field strength. These are of primary importance in optimizing ER fluids for applications such as clutches, brakes, viscous dampers, pumps, and robotic ac...

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Design of anhydrous electrorheological (ER) suspensions based on I₂‐doped poly(pyridinium salt)

Cited by 14 publications

References 21 publications

A modified conduction model for the electrorheological effect

A modified conduction model for the electrorheological effect

Correlation between Generated Shear Stress and Generated Permittivity for the Electrorheological Response of Colloidal Silica Suspensions

Direct synthesis of electrorheological suspension containing salt of poly(methacrylic acid) and its electrorheological effect

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Design of anhydrous electrorheological (ER) suspensions based on I2‐doped poly(pyridinium salt)

Cited by 14 publications

References 21 publications

A modified conduction model for the electrorheological effect

A modified conduction model for the electrorheological effect

Correlation between Generated Shear Stress and Generated Permittivity for the Electrorheological Response of Colloidal Silica Suspensions

Direct synthesis of electrorheological suspension containing salt of poly(methacrylic acid) and its electrorheological effect

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Design of anhydrous electrorheological (ER) suspensions based on I₂‐doped poly(pyridinium salt)