Dynamic dielectric behaviour of structuring dispersions. I. Development of a measuring device

The physical properties of colloidal dispersions often depend on the mechanical shear history. The dependency can be explained in terms of shear-induced changes in particulate structures. A full understanding of the physical behaviour requires, therefore, measuring techniques that are able to analyse the varying structure. An instrument is presented which can follow the changing dielectric spectrum at low frequencies under various shear histories. The mechanical requirements of such a device are discussed. The performance of the electronics is verified by means of computer simulation. The application of the instrument is demonstrated for a carbon black dispersion; the evolution of the dielectric spectrum, after cessation of flow, is followed.