The Dielectric Characteristics of Thermoplastics Nanocomposite Materials with Ferrites

This paper presents the obtaining and characterization of thermoplastics nanocomposite materials with ferrites with applications in the electromagnetic shielding of vehicle interiors (mainly automotive electronics-carcasses) from the electromagnetic radiation emitted mainly by exterior sources-electrical lines and supply sources-in terms of the development of the new electrical vehicles. With this aim, suitable polymer composite materials were developed by extrusion and samples for testing through a melt injection process. The characterization of the obtained materials took into account the requirements imposed by the desired applications. The variations of the tangent of the dielectric loss angle $(\operatorname{tg} \delta$) and electrical conductivity ($\sigma$) over the frequency range of $8-30 \mathrm{MHz}$ were studied for the composite materials, in order to appoint the best frequency domain for the application. The variation in the dielectric properties of polymer composites with frequency is typically associated to the dipole and interfacial polarization between the conductive filler and the polymer matrix, as well as to the relaxation mechanisms.