STUDIES OF ER FLUIDS FEATURING RODLIKE PARTICLES

Chaining of micron-sized polarizable particles in ER fluids is generally accepted to be responsible for the liquid-to-solid transitions on the application of an external electric field. It has been hypothesized that the strength of the particle-particle interactions solely determines the rheological properties of ER fluids. In our work, the particle’s structure has been used to control interactions; for example, we have developed systems featuring rodlike particles. With such particles it should be possible to enhance the dielectric interaction of the particles as well as their mechanical interaction. The main goal of our effort has been to distinguish between these two mechanisms through measurements of the dielectric properties in conjunction with the rheological responses. Based on the experimental evidence thus far gathered, we can state that most, but not all, of the rheological effects are explainable in terms of the dielectric changes in the fluid.