Time domain spectroscopic measurements of the dielectric properties of heterogeneous materials

摘要

In recent years the powerful new techniques of time domain dielectric spectroscopy (TDDS) have revolutionized the field of high frequency dielectric measurements. However, due to the relative newness of the method many questions remain unresolved concerning the applicability of TDDS and the interpretations and limitations of the measurements. In previous and continuing work we have attempted to use TDDS to detect and follow phase changes when a homogeneous single phase liquid transforms into a two phase system consisting of a dispersion of small particles of the new second phase in the remaining original phase.[1] Although the TDDS system provides a good way to detect the phase changes as a function of transition temperature and composition, questions remain about the meaning of the calculated dielectric permittivity (ε' and ε″) of the two phase system. The present investigation was undertaken to obtain experimental results for two phase systems with separately known dielectric properties for the somewhat more interesting case of solid polymer particles in a dielectric fluid.