Electrorheological properties of silica suspensions

Authors:
  • YOYasufumi Otsubo
    Yasufumi Otsubo
  • MSMasahiro Sekine
    Masahiro Sekine
  • SKShingo Katayama
    Shingo Katayama
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Abstract
Monodisperse silica particles were formed by hydrolyzing tetraethylorthosilicate in an ethanol solution. For silica suspensions in a silicone oil, the steady‐shear viscosity and dynamic viscoelasticity were measured under electric fields up to 3.0 kV mm−1. At low shear rates and high field strength, the flow curve shows a plateau, showing development of a yield stress. The yield stress is proportional to the volume fraction of particles (Φ) and to the square of the electric field (E) for Φ<0.3. The number of chains linearly increases with volume fraction. At higher volume fractions it varies with (ΦE)2.4. The larger value of the exponent may be attributed to the crosslinking of chains. The scaling on Mason number is not applicable to the viscosity behavior in steady shear. This implies that the electric polarization forces are much stronger than predicted by the bulk polarization theory. The interparticle forces due to polarization are closely related to conditions at the surfaces of the particles, rather...