Background: As a kind of intelligent materials, electrorheological (ER) fluids have been
researched increasingly deeply and widely. Dynamic viscoelastic property is an innate and important
property of EF fluids, which can be controlled by external electric field strength (E). However, viscoelasticity
of zeolite-based ER fluids has not been researched deeply in small strain under enhanced E.
Methods: This work is focused on the dynamic viscoelasticity under enhanced E with small oscillation
amplitude. In this work, zeolite-based ER fluids were prepared with five mass fractions, and their dynamic
viscoelastic properties were measured by a commercial rheometer under small amplitude oscillation
in E sweep mode.
Results: Two singular points including the inflected point and the crossover point under different angular
frequencies were observed for the first time in various concentrations of ER fluids when chains
or clusters formed with E increasing. The inflected E increased with mass fraction of ER fluid increasing,
while loss tangent (tanθ) decreased slightly. The crossover E decreased with mass fraction of ER
fluid increasing, while tanθ increased.
Conclusion: In this work, ER fluids in five mass fractions showed concentration-dependent inflection
of tanθ, in which inflected E increased and inflected tanθ decreased slightly with the concentration increasing.
The inflection was ascribed to similar elastic properties and viscous force under applied electric
field in different angular frequencies here. Besides, the crossover of tanθ showed frequencyindependent
and concentration-dependent properties which were explained by a viscoelastic model.