Electrorheological Fluids (eBook)

Cover 1
Table of Contents 11
Preface 8
Colloidal suspensions and electrorheological fluids 18
Colloidal suspensions 18
Particle surface charge in aqueous systems 19
Relationship between surface charge density and Zeta potential 24
Electrorheological suspensions—nonaqueous system 31
References 33
Viscosity of liquids and colloidal suspensions with and without an external electric field 35
Pure liquids 36
Viscosity of pure liquids 36
The ER effect of pure liquids 40
Colloidal suspensions 44
The viscosity of colloidal suspensions 44
Derived from Eyring's rate theory 44
Derived from Einstein's equation 50
Determine the parameter n 60
Contribution from particle surface charge 68
Electroviscous effect of colloidal suspensions 74
Polymers and polyelectrolyte solutions 80
The viscosity of the polyelectrolyte and polymer melt 80
Viscosity equation of the polymer melt 80
Viscosity equation of the polymer solution 84
The viscosity equation derived from Eyring's rate theory 84
Theta condition 84
Good solvent 88
The viscosity equation derived from Einstein's equation 89
The electroviscous effect of polyelectrolytes 93
Concluding remarks 96
References 96
The positive, negative, photo-ER, and electromagnetorheological (EMR) effects 100
Positive ER effect 100
Negative ER effect 109
Photic (Photo-)ER effect 120
Electromagnetorheological (EMR) effect 123
Magnetorheological (MR) effect 123
The EMR effect 127
References 129
The electrorheological materials 131
General feature of ER fluids 131
Preparation of ER fluids 132
Liquid continuous phase 133
Dispersed phase 135
Solid particle-heterogeneous electrorheological materials 135
Inorganic oxide materials 135
Non-oxide inorganic materials 136
Organic and polymeric materials 136
Liquid material-homogeneous ER fluid 140
Additives 141
Stability of ER suspensions 148
Positive ER materials 153
Aluminosilicates 154
Conductive organics and polymers 155
Oxidized polyacrylonitrile 155
Polyanilines and polypyrroles 156
Carbonaceous materials and fullerenes 157
Superconductive materials 159
Liquid materials 159
Immiscible with the dispersing phase 159
Miscible with the dispersing phase 160
Core-shell composite particulates 162
Design of high performance positive ER fluids 162
Negative ER materials 163
Photo-ER materials 163
Electro-magneto-rheological materials 164
References 169
Critical parameters to the electrorheological effect 169
The electric field strength 169
Frequency of the electric field 173
Particle size and shape 179
Particle conductivity 186
Particle dielectric property 192
Particle surface property 205
Particle volume fraction 215
Temperature 225
Liquid medium 238
Electrode pattern 244
References 247
Physics of electrorheological fluids 252
Forces relevant to the ER effect 252
Hydrodynamic force 253
Brownian motion 254
Electrostatic force 255
van der Waals forces 256
Molecular level 256
Macroscopic level 258
Polymer induced forces 259
Steric repulsive force 260
Depletion attractive force 260
Adhesion force due to water or surfactant 261
Electric field induced polarization force 263
Relative magnitude of interparticle interaction 264
Scaling analysis using the Mason number for ER fluids 265
Phase transition 267
Phase transition in colloidal suspensions 267
Phase transition in ER suspensions 269
Percolation transition 274
Percolation theory 274
Percolation transition in ER suspensions 277
Rheological properties 286
Steady shear behavior 286
Dynamic rheological property 298
Strain dependence 298
Frequency dependence 311
Simulation results 320
Transient shear 324
Structure determination using scattering technology 328
Conductivity mechanism 334
Localization models 335
Charging Energy Limited Tunneling (CELT) 335
Quasi-One-Dimensional Variable Range Hopping (Quasi-ld-VRH Model) 336
Conductivity under a zero mechanical field 338
Conductivity under an oscillatory mechanical field 342
Polarization process 353
References 353
Dielectric property of non-aqueous heterogeneous systems 358
Basic dielectric parameters 358
Kramers-Kronig relations 361
The polarization types and their relaxation times 361
Polarization type 362
The electronic polarization 362
The atomic polarization 363
The ion polarization 363
Debye polarization 364
The electrode polarization 364
The Wagner-Maxwell polarization 368
Relative relaxation times of polarization 371
Temeprature dependence of the relaxation time 375
Dielectric relaxation 380
Single relaxation time 380
Multiple relaxation times 382
Dielectric property of mixture 384
Dielectric property of non-aqueous systems with charging agent 389
Charging agent 389
Charging mechanisms based on the conductivity data 390
The electrode polarization in non-aqueous systems 401
Inverse micelle size calculated from the dielectric property 404
The dielectric property without electrolytes 406
The Wagner-Maxwell model for dilute suspensions 406
Dilute suspensions of spherical particle with shell 411
The Hanai model for concentrated suspensions 413
Particle shape effect on the dielectric property 415
The Wagner-Maxwell-Sillars equation and its extensions 418
The Bottcher-Hsu equation 422
The Looyenga equation 422
Comparison between the mixture equations 423
dc transient current 430
Calculate the space charge amount from the dc transient current decay curve 432
Calculate the dielectric property of the material from the dc transient current 435
References 437
Dielectric properties of ER suspensions 441
Introduction 441
Dielectric property of the ER suspensions of spherical or quasispherical particles 443
Theoretical treatment on the dielectric criteria for high performance ER suspensions 457
The yield stress equation 466
Particle shape effect on the dielectric properties of ER suspensions and their ER effect 483
The response times of ER suspensions 486
Dielectric properties under a high electric field 487
Summary 488
References 490
Mechanisms of the electrorheological effect 492
Fibrillation model 492
Electric double layer (EDL) model 494
Water/surfactant bridge mechanism 495
Polarization model 496
Conduction model 510
Dielectric loss model 523
References 532
Applications of the electrorheological fluids 535
Mechanical force transferring and controlling devices 535
ER composite materials 545
ER inks and pigments 549
Photonic crystals 553
Mechanical polishing 554
ER tactile and optical displays 557
ER sensors 563
ER application for drug delivery 563
Summary and outlook 566
References 567
INDEX 570