Office Imaging Research and Technology Development tastman Kodak Company, Rochester NY 14653-6402

摘要

The induced polarization of a dielectric particle can be drastically altered by surface phenomena. A thin ohmic surface layer screens electric fields from the bulk of a particle thereby greatly increasing the static polarization. Furthermore, the finite response time of charge in the surface layer introduces a time dependence that manifests itself as a relaxation in the polarization. The importance of surface effects is apparent in a variety of interesting particulate systems. Technologies in which electrical surface phenomena are important include electrorheo-logical fluids, electrophotography, electrofusion of biological cells, and electrophoretic separation, Electrorheological fluids are particularly reliant on mechanisms of surface polarization. In this article, the surface polarization of small particles is investigated by studying a model ER fluid: moistened glass particles in an insulating oil. Characterizing the polarization mechanism is a crucial step in understanding and developing ER fluids.