ER-Fluids Based on Polyurethane Dispersions: Structure and Properties

Bloodworth, Robert; Wendt, Eckhard

doi:10.1007/978-1-4899-1036-3_14

Cited by 11 publications

(11 citation statements)

References 4 publications

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“…In dry state, they can show strong ER response to AC electric fields. 7 Some doped inorganics, such as zirconium-doped aluminosilicates, rare earth ion doped titania, etc., can also show strong ER property under DC electric fields. 8 Because of inherently high density and stiffness, however, these inorganic ER particles have to be subjected to problems involving particle sedimentation and abrasiveness to devices.…”

Section: ■ Introductionmentioning

confidence: 99%

Influence of Side Chain Sizes on Dielectric and Electrorheological Responses of Poly(ionic liquid)s

et al. 2017

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Poly(ionic liquid)s (PILs) show potential as new anhydrous polyelectrolyte-based smart electrorheological (ER) materials. Understanding the structure-property relationship on a molecular level is very important for guiding the design of PIL-based ER materials. In this paper, a family of (p-vinylbenzyl)trialkylammonium hexafluorophosphate-based PIL particles containing different length of substituent alkyl chains attached to immobile ammonium charged site is synthesized for especially understanding the size effect of side chains on ER property. To exclude the particle shape effect, the PIL particles are controlled to be monodisperse sphere-like morphology with a similar size. The ER property of PIL particles when dispersed in insulating oil is investigated and compared by temperature-modulated rheological test under external electric fields. The dielectric spectroscopy is finally performed to study the mechanism behind the size effect of side chains on the ER property of PIL particles. We demonstrate that the size of side chains on the charged site has a significant impact on the ER effect of PIL particles and the PIL particles with shorter side chains have stronger ER property but degraded temperature dependence, and this is related to the fact that the variation of side chain size alters the transport dynamic of mobile counterions and ion motion-induced interfacial polarization.

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Section: ■ Introductionmentioning

confidence: 99%

Influence of Side Chain Sizes on Dielectric and Electrorheological Responses of Poly(ionic liquid)s

et al. 2017

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“…Cellulose, 1 starch, 2,3 silica, 4 zeolite, 5 titanium oxide, 6 tin (II) oxide, and sulfopyropyl dextran 7 have been widely used as dispersed phases in the formulation of the hydrous (wet) ER fluids, which have several problems relating to durability, limited temperature, and colloidal instability in industrial use. Recently, anhydrous (dry) ER fluids (which do not contain water or any other polar solvent in the disperse phase) have been introduced, which consist of polyaniline, 8 polyurethane, 9 polypyrrole, 10 poly(tert-butylacrylate-stat-lithium acrylate)-blockpolyisoprene, 11 and polyisoprene-block-poly(carboxylithium styrene) 12 as organic dispersed phases. However, these also have shown some problems in applications such as instability of dispersions to sedimentation, a narrow temperature range of operation, and corrosion.…”

Section: Introductionmentioning

confidence: 99%

Electrorheological properties of poly(lithium‐2‐acrylamido‐2‐methyl propane sulfonic acid) suspensions

Ünal

Yılmaz

2002

J of Applied Polymer Sci

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ABSTRACT:In this study, poly(2-acrylamido-2-methyl-1-propane sulfonic acid) (PAMPS) was synthesized using potassium persulfate (K 2 S 2 O 8 ) as initiator. PAMPS (M n ϭ 36,000 g/mol) was partially converted to a lithium salt (PAMPS-Li), and particle size was determined to be 40 m. Suspensions of PAMPS-Li at various concentrations were prepared in silicone oil, mineral oil, dioctylphthalate (DOP), and trioctyltrimellitate (TOTM) insulating oils. Colloidal stabilities of these suspensions were determined at 20 and 80°C. The PAMPS-Li suspensions were observed to provide an electrorheological (ER) response upon the application of an external dc electric field. ER properties of these suspensions were investigated at various shear rates (␥ ) and electric field strengths (E). Further, effects of polar promoters and high temperature on ER activity were determined, and excess shear stresses (⌬) were calculated. A shear-thinning nonNewtonian viscoelastic behavior was observed for the PAM-PS-Li suspensions.

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“…Other properties of ER fluids, such as temperature stability, sedimentation rate, and abrasion, have been improved remarkably in the last few years. ͑See reports from various manufacturers: Bridgestone, 7 Lord Corporation, 8 Bayer AG, 9 Lubrizol, 10 Advanced Fluid Systems, 11 and Nippon Shokubai. 12 ͒ Recently, it has been realized that for dc excitation the conductivity mismatch between particles and fluid is a dominant factor in determining fluid strength.…”

Section: Introductionmentioning

confidence: 99%

Time-dependent and nonlinear effects in electrorheological fluids

Davis

1997

Journal of Applied Physics

104

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An integral equation method is used to calculate particle-particle forces in electrorheological fluids. The method focuses on the gap region between particles where large electric-field concentrations occur. Effects due to time-dependent excitation and nonlinear ͑field-dependent͒ fluid conductivity are analyzed. It is found that the response to step-function changes in applied field closely follows a simple form that can be derived from the dipole approximation. Qualitatively different stress-vs-time curves are obtained for large dielectric mismatch ͑e.g., barium titanate/dodecane͒ relative to large conductivity mismatch ͑zeolite/silicone oil͒. In fluids where the conductivity is strongly field dependent, it is found that particle-particle forces scale linearly with applied field E 0 at large fields. Likewise, the shear yield stress scales as E 0 3/2 .

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ER-Fluids Based on Polyurethane Dispersions: Structure and Properties

Cited by 11 publications

References 4 publications

Influence of Side Chain Sizes on Dielectric and Electrorheological Responses of Poly(ionic liquid)s

Influence of Side Chain Sizes on Dielectric and Electrorheological Responses of Poly(ionic liquid)s

Electrorheological properties of poly(lithium‐2‐acrylamido‐2‐methyl propane sulfonic acid) suspensions

Time-dependent and nonlinear effects in electrorheological fluids

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