IS THE MAXWELL-SILLARS-WAGNER MODEL RELIABLE FOR DESCRIBING THE DIELECTRIC-PROPERTIES OF A CORE-SHELL PARTICLE EPOXY SYSTEM

Dielectric measurements have been performed on neat acrylic core-shell particles, and core-shell modified-epoxy networks in order to assess the accuracy of the Maxwell-Wagner-Sillars (MWS) model in describing t he dielectric properties of heterogeneous polymeric systems. Measured and predicted interfacial polarizations are compared. The temperature dependence of the frequency of maximum interfacial dielectric loss pro cess is well described by the MWS model and from the temperature depen dence of the conductivity of the two phases. However, the measured and predicted absolute values differ and a distribution in the interfacia l relaxation time is observed. This is attributed to the effect of a g radient in concentration across the interface between the acrylic part icles and the epoxy matrix. It is thus concluded that the nature and p roperties of interphases can strongly influence the dielectrical prope rties and interfacial polarization processes in polymer blends, and th at theoretical models which do not take into account details of interf acial charge transfer might not be reliable in describing the morpholo gy of heterogeneous polymeric systems. (C) 1998 Elsevier Science Ltd. All rights reserved.