Dielectric modeling of multiphase composites

In this paper effective medium theory based on Clausius–Mossoti relation was used to predict dielectric properties of multiphase composite system. The composite consisted of E-glass fibers (plain weave S-glass, J.B. Martin) embedded in bisphenol A diglycidylether epoxy matrix (D.E.R. 324, D.O.W. chemicals) with hollow ceramic spherical inclusions (SF 14, P.Q. Corp.) at different volume fractions. In many engineering applications, materials with designed dielectric properties are often sought. An important question in engineering design of a composite material is how the overall properties of the composite depend on those of the individual constituents. Mixing the epoxy resin with hollow ceramic inclusions can effectively reduce dielectric constant of the resin, which is often desirable, rendering composites as good candidates for many applications, especially in telecommunications. Compensation for degradation of mechanical properties of matrix (due to inclusion insertion) is obtained by embedding fibers into the mixture. Measurements of dielectric constant and loss tangent for this multiphase composite system were conducted in the region between 0.1 and 100 kHz range using DEA 290 (T.A. Instruments) dielectric analyzer and experimental results are presented. Good correlation between analytical model and experimental results was observed throughout all frequency range of investigation.

► We model dielectric properties of multiphase composites based on epoxy, ceramic and E-glass.
► Ceramic volume fraction highly influences dielectric constant and deteriorates mechanical properties of the composite.
► Experimental dielectric data within 0.1–100 kHz range is in good correlation with proposed analytical model.
► Multiphase composite dielectric properties depend on volume fractions of constituents and their properties.
► Multiphase dielectric properties can be accurately predicted.