Microwave characterization of filled polymers

Abstract

Interest in filled polymers has expanded in recent years as investigators have recognized the great flexibility allowed by these materials to suit particular properties such as electrical, mechanical, and/or coupling between these properties. This article describes the work undertaken to investigate the microwave response of two different types of samples: one with carbon black or silica particles embedded in a linear low-density polyethylene, and the other with carbon black particles or carbon fibers embedded in an epoxy resin. We report broad-band (30 MHz–14 GHz) measurements of the complex permittivity of these materials obtained by measuring the scattering parameters (S parameters) of a microstrip line loaded with a rectangular sample of the test material. The experimental results presented give access to data which can be rationalized in terms of a combination of Bruggeman’s self-consistent model with Jonscher’s phenomenological analysis. This analytical approach yields data that are in good correspondence with experimental data in terms of the concentration dependence of inclusions within the polymeric matrixes and demonstrates large practical capabilities for analyzing the electromagnetic properties of these materials at microwave frequencies because it allows one to make an explicit connection between these properties and the experimentally accessible parameters.

Use of Fillers to Enable the Microwave Processing of Polyethylene

“…Previous work has concentrated on the dielectric properties of thermoplastics [Bur, 1985;Chen et al, 1993b], and although a few studies involved the heatability of some thermoplastics [Chen et al, 1993a;Chen et al, 1993c;Ku et al, 2000] there has been little emphasis on improving the microwave response of thermoplastics with low dielectric properties. Brosseau et al [2001] have reported microwave dielectric spectroscopic measurements on carbon and silica fi lled polyethylene as well as an epoxy resin [Brosseau et al, 2001]. The aim of our research is to investigate the effect of the use of commonly used fi llers such as talc, zinc oxide and carbon black on the improvement of microwave response of highdensity polyethylene (HDPE) so as to be able to thermoform such materials without signifi cantly compromising the mechanical properties of the virgin polymer.…”

The Impact of Blue Inorganic Pigments on the Microwave Electrical Properties of Polymer Composites

“…The Bruggeman effective medium theory has the virtue of simplicity. It can be used with the assumption that the inclusions do not interact each other and that are randomly distributed in the matrix [24]. In the most commonly used form, that is, the implicit form,…”

Polymer Nanocomposites: Synthesis and Physical Properties

“…Chemical stability of polymers allows using them in severe conditions (Hong et al, 2003). Modification of polymers with various inorganic fillers is used for altering their mechanical, electric, and other operational properties (Brosseau et al, 2001). The intensity of these properties' change depends on the nature, composition, morphology, and concentration of filler, as well as parameters of the flow process of filler's introduction into the matrix.…”