Structure and dielectric properties of a thermoplastic blend containing dispersed metal

Abstract

AbstractIn the present work broadband dielectric relaxation spectroscopy measurements were employed to investigate the dielectric properties of polymer composites. A polyethylene/polyoxymethylene (PE/POM) thermoplastic blend was used as a matrix, while the inclusions were iron (Fe) particles. For comparison, the two pure polymers‐ PE and POM‐ were used as a matrix, too. In the PE/POM‐Fe composites, the polymer matrix is two‐phase and the filler particles are localized only in the POM phase, resulting in an ordered distribution of the dispersed filler particles within the blend. In PE‐Fe and POM‐Fe composites, the filler spatial distribution is random. The behaviour of all the composites studied is described in terms of the percolation theory. The PE/POM‐Fe composites, based on the PE/POM blend, demonstrate different electrical behaviour compared to that of POM‐Fe and PE‐Fe systems. The percolation threshold value of the PE/POM‐Fe composites was found much lower than that of the other two systems. The results were related to the microstructure of the composites. A schematic model for the morphology of the composites studied has been proposed. This model explains the peculiar behaviour of the PE/POM‐Fe composites by taking into account the ordered distribution of the filler particles in a binary polymer matrix. Optical microscopy photographs confirm this model.