Abstract
We experimentally investigate the rotation of plate shaped aggregates of clay mineral particles immersed in silicone oil. The rotation is induced by an external electric field. The rotation time is measured as a function of the following parameters: electric field strength, the plate geometry (length and width) and the dielectric properties of the plates. We find that the plates always align with their longest axis parallel to the direction of the electric field (E), independently of the arrangement of individual clay −2 mineral particles within the plate. The rotation time is found to scale as E and is proportional to the viscosity (μ), which coincides well with a model that describes orientation of dipoles in electric fields. As the length of the plate is increased we quantify a difference between the longitudinal and transverse polarisability. Finally, we show that moist plates align faster. We attribute this to the change of the dielectric properties of the plate due to the presence of water.
Highlights
Electrorheological fluids are able to change their material properties on application of an external electric field
The clay mineral particles align themselves with the electric field, undergoing interactions between each other which eventually leads to the formation of dipolar chains that span the gap between the electrodes
The magnitude of the electric torque is related to the strength of the electric dipoles induced on the clay particle aggregates
Summary
Electrorheological fluids are able to change their material properties on application of an external electric field. The clay mineral particles align themselves with the electric field, undergoing interactions between each other which eventually leads to the formation of dipolar chains that span the gap between the electrodes. This interaction can cause the viscosity to drastically change, typically orders of magnitude. The initial rotation may take a couple of milliseconds for powdered sodium fluorohectorite (Na-FH) [11] This is short in comparison with the time needed for the formation of long particle chains that often span the entire gap between electrodes. The present article is a comprehensive study with new results and interpretations based on preliminary studies published previously [14]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call