Electro-rheological materials

Gavin H. P., The effect of particle concentration inhomogeneities on the steady flow of electro- and magneto-rheological materials. J. Non-Newton. Fluid Mech. 71 (1997)pp. 165-182. 

K. Minagawa, K. Koyama, Electro- and magneto-rheological materials, stim-uli-induced rheological functions, Curr. Org. Chem., 2005,9,1643. 

F.E. Filisko, L.H. Radzilowski, An intrinsic mechanism for the activity of alumino-silicate based electrorheological materials, J. Rheol, 1990,34,539. H. Block, J.P. Kelly, Electro-rheological fluids, UK Patent 217051B, 1986. 

Nikitczuk J, Weinberg B, and Mavroidis G, Control of electro-rheological fluid based resistive torque elements for use in active rehabilitation devices. Smart Materials and Structures, vol. 16, pp. 418-428,2007. 

Chen, S. H., Yang, G. (2003). A method for determining locations of electro-rheological dampers in structures. Smart Materials and Structures, 12, 164. doi 10.1088/0964-1726/12/2/302... 

This transition from a homogeneous towards a nonhomogeneous flow has been reported in complex fluids of various microstructure such as lyotropic micellar and lamellar phases [44,121,122], triblock copolymers solutions [123,124], viral suspensions [125], thermotropic liquid crystal polymers [126], electro-rheological fluids [127], soft glassy materials [128], granular materials [129,130], or foams [131-133]. 

Recently there has been much interest in composites of magnetic particles in a soft matrix which respond to a magnetic field by a change of shape and properties [147]. These materials are the elastomeric equivalents of magneto-rheological fluids and electro-rheological fluids. 

Optical and electro-optical behavior of side-chain liquid crystalline polymers are described 350-351>. The effect of flexible siloxane spacers on the phase properties and electric field effects were determined. Rheological properties of siloxane containing liquid crystalline side-chain polymers were studied as a function of shear rate and temperature 352). The effect of cooling rate on the alignment of a siloxane based side-chain liquid crystalline copolymer was investigated 353). It was shown that the dielectric relaxation behavior of the polymers varied in a systematic manner with the rate at which the material was cooled from its isotropic phase. 

Among the adaptive materials currently on the forefront are liquid crystals, electro- and magneto-rheological (ER/MR) fluids, thermo- and physioreponsive gels, and shape memory alloys. In all but the last case, these systems involve... 

Binary mixtures of a flexible polymer and a rigid rod-like molecule (nematogen or liquid crystal) play an important role in electro-optical devices, such as light shutters and displays. Since the miscibility or phase separation controls the performance of the materials, the phase behavior and phase separation kinetics have been of fundamental and practical interests. Liquid crystalline domains dispersed in a polymer matrix are called polymer dispersed-liquid crystals (PDLCs), or polymer-stabilized liquid crystals (PSLCs), where the polymer forces the liquid crystals to phase separate into droplets surrounding by the polymer matrix [2]. Practically, there are many ways to create PD LCs by mixing polymers and liquid crystals the emulsion method [37] and phase separation method [38], including polymerization-, thermally-, and solvent-induced phase separations. The reader is referred to text books [1, 2] for details of PDLC and a review [39] for the rheological and mechanical properties. 

---