Electrorheological suspension

J. Kadaksham, P. Singh and N. Aubry, Dynamics of electrorheological suspensions subjected to spatially nonuniform electric fields. Journal of Fluids Engineering, 126(2), 170-179 (2004). 

H.Q. Xie, J.G. Guan, Study on electrorheological properties of semiconducting polyaniline-based suspensions, Angew Makromol. Chem., 1996,235,21. S.Z. Wu, S. Lu, J.R. Shen, Electrorheological suspensions, Polym. Int, 1996, 41,363. 

Journal of Applied Polymer Science 68, No. 13, 27th June 1998, p.2169-74 ONE-STEP PREPARATION OF ELECTRORHEOLOGICAL SUSPENSION CONTAINING POLY(LITfflUM ACRYLATE) VIA INVERSE EMULSION POLYMERISATION AND STUDY OF ITS ELECTRORHEOLOGICAL EFFECT... 

Keywords Carbon nanotube, nanocomposite, radical polymerization, suspension polymerization, in-situ polymerization, electrorheology. 

Electrorheology of Polymer/CNT Nanocomposites Prepared by in-situ Suspension Polymerization... 

Electrorheological phenomenon is demonstrated in Figure 8.13 on optical microscope images of two different types of CNT microspheres. Both are based on PMMA matrix but in the first case the particles were prepared by in-situ suspension polymerization in presence of MWCNT (570 and in the second by MWCNT adsorption on separately prepared PMMA microspheres (20). Particles were dispersed in silicon oil and placed between two parallel electrodes. Figure 8.13(a) represents the state without and Figure 8.13(b) with applied electric field. In the figure, typical ER fibril structures can be observed for both principal materials when external electric field is applied the dispersed PMMA/MWCNT microspheres form chain structures. 

Electrorheological properties of fluids, in this case PS/MWCNT suspensions in silicone oil, can be demonstrated in the form of flow curves obtained from measurements on a rotational rheometer in the absence and presence of external electric field (21). The flow curves expressing shear stress vs. shear rate dependence are... 

Four novel approaches to contemporary studies of suspensions are briefly reviewed in this final section. Addressed first is Stokesian dynamics, a newly developed simulation technique. Surveyed next is a recent application of generalized Taylor dispersion theory (Brenner, 1980a, 1982) to the study of momentum transport in suspensions. Third, a synopsis is provided of recent studies in the general area of fractal suspensions. Finally, some novel properties (e.g., the existence of antisymmetric stresses) of dipolar suspensions are reviewed in relation to their applications to magnetic and electrorheolog-ical fluid properties. 

Intimately related to these magnetic-field suspension rheology developments is the growing field of electrorheology, which involves comparable electric fields and was the subject of an international symposium (Carlson and Conrad, 1987). 

There are also complex fluids that change from solid-like to liquid-like, or vice versa, when subjected to a modest deformation. Complex fluids of this type include particulate and polymeric gels. Some fluids change to solids when an electric or magnetic field is applied these are electrorheological and magnetorheological suspensions. A classical liquid or solid, on the other hand, does not change character in response to a weak field unless it is extremely close to a phase transition temperature. 

J. Yin, X. Xia, L. Xiang, Y. Qiao, and X. Zhao, The electrorheological effect of polyaniline nanofiber, nanoparticle and microparticle suspensions. Smart Mater. Struct., 18, 095007 (llpp) (2009). 

J. Plocharski, H. Drabik, H. Wycishk, T. Ciach, Electrorheological Properties of Polyphenylene Suspensions. Synth. Met. 1997,88,139-145. 

Electrorheological (ER) fluid is a smart suspension, whose structures and rheological properties can be timed by an external electric field. The ER fluid consists of micrometer-size leaking dielectric particles in an insulating liquid. Under the influence of an applied electric field, the dispersed dielectric particles are polarized and attracted each other to form chainlike structures (see Figure 14.1). 

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