Electrorheological properties of PDMS/carbon black suspensions under shear flow |
| |
Authors: | Marianna Kontopoulou Michael Kaufman Aristides Docoslis |
| |
Institution: | (1) Department of Chemical Engineering, Queen’s University at Kingston, Kingston, ON, K7L 3N6, Canada |
| |
Abstract: | Suspensions of polydimethylsiloxane (PDMS) containing low amounts (1 wt.% or less) of a highly conducting carbon black (CB)
filler are rendered conductive and exhibit electrorheological (ER) responses under shear flow when exposed to an externally
applied AC electric field. The presence of columnar structures, consisting of CB particles aligned in the direction of the
electric field is evidenced through optical microscopy experiments. The appearance of yielding behavior and positive ER response,
manifested by an increase in the viscosity of the suspensions, depend strongly on the filler loading, strength of the electric
field, magnitude of the shear field, and viscosity of the medium. The responses are stronger at low filler loadings, below
the percolation threshold, and at very low shear rates, where the microstructure of the dispersed phase remains intact. At
higher shear rates, corresponding to Mason numbers (Mn) above 1, the structure is disrupted and thus does not contribute to
the observed shear stress. The rheological characterization is accompanied with admittance measurements, to demonstrate that
the induced polarization forces between particles lead to the formation of electrically conductive structures within the polymer
matrix. A critical comparison with the qualitative predictions based on the theory of induced dipole–dipole interactions shows
that the theory is valid for these dilute systems. |
| |
Keywords: | Electrorheology Carbon black Conductive polymers Carbon black– polymer composites PDMS |
本文献已被 SpringerLink 等数据库收录! |
|