Produção e caracterização de polímero magnético e isolante elétrico via processo físico de deposição

Abstract

Nanoparticles (NPs) exhibit different chemical and physical properties from their bulk counterparts due to surface effects and shape that arise due to the quantum confinement effect. Two physical phenomena of magnetic nanoparticles are technologically important: The superparamagnetic state and the formation of monodomains, which arise when particles have their size reduced to the nanometer scale (<100 nm). This particularity of magnetic NPs can be combined with a polymer matrix, resulting in a material that is electrical insulating and has magnetic properties. In the present work a synthetic method based on the physical deposition process of metallic particles on the high-density polyethylene powder via magnetron sputtering is used, with variation in the deposition time of ferro-nickel alloy particles, called permalloy, resulting in different metallic concentrations in the polymeric substrate. The DC magnetization measurement technique was used for magnetic characterization of the synthesized material and the electrical properties were characterized by impedance spectroscopy, which uses alternating voltage and current signal at different frequencies, and linear scanning voltammetry, which uses continuous signal of voltage and current. Measurements of estimated metal concentration in the polymer were obtained by the EDS (Energy dispersive x-ray spectroscopy) and RBS (Rutherford Backscattering Spectroscopy) techniques. For morphological characterization of the material obtained, Scanning Electron Microscopy (SEM) was used. From the magnetic measurements, the diameter of the particle agglomerates was obtained by Langevin Function simulation, indicating the existence of superparamagnetic nanoparticles, organized in magnetic monodomains. This material is potentially attractive from a technological point of view for applications in transformers, replacing the traditional ferrous cores, having the advantage of being a lighter material, with dielectric properties, with a significant absence of magnetic hysteresis and free of eddy currents.