Domain structure and MR effect of ferrofluid emulsion

Blends of immiscible liquids with different dielectric constants and viscos ities were known to show the ER effect due to the change of the domain stru cture by the electric field. In this paper, we report on our attempt to exp lore the possibility of the magnetic analog of these blend-type ER fluids. Waterbased ferrofluid was blended with silicone oil with higher viscosity t han the ferrofluid, in order to see whether the negative MR effect can be i nduced. The domain structure and the viscosity under the magnetic field and shear flow were studied. Growth of the droplet due to coalescence was obse rved under the field, which resulted in the gradual decrease of the shear v iscosity.