Processamento e caracterização de um compósito magnetocalórico com polímero condutor : PAni-CSA/Gd5,09Ge2,03Si1,88

Abstract

To glimpse any applicability to the magnetocaloric compounds, it is necessary to take into account subsequent processes in these compounds, since in many cases it is indispensable a specific geometry (e.g., plates, cylinders, spheres, nanoparticles, etc.) without severe detriment of the magnetic and magnetocaloric properties of interest. In light of this, this Master s Thesis introduce a processing route of the first magnetocaloric composite with conductive polymer wherein the magnetocaloric reinforcement is the fragile compound Gd5,09Ge2,03Si1,88 and the ductile matrix is the conductive polymer polyaniline doped by camphorsulfonic acid (PAni-CSA) , since the previously magnetocaloric composites resort insulating resins or thermoplastic polymers that reduce the performance when applied to magnetic refrigeration technologies.This Master s These investigates two variables of the developed processing route: concentration of PAni-CSA (in mass, numeric type) and sintering (in °C/h, categorical type of sintering and non-sintering). The presented results are for two stage: (1) pre-test to define the parameters of the 2² factorial design with center point, in duplicate, by varying the concentration of PAni-CSA and sintering; and (2) the experimental design stage to optimize these two variables.The studies include a discussion about the composites magnetic and magnetocaloric properties, as well as include analysis by scanning electron microscopy and Vickers microhardness. Furthermore, it is also included individual characterizations of the magnetocaloric reinforcement (namely: X-ray diffraction, scanning electron microscopy and magnetic and magnetocaloric properties) and the polymeric binder (namely: X-ray diffraction, thermogravimetry, differential scanning calorimetry, spectroscopy in the infrared region by Fourier transform, molecular absorption spectrometry ultraviolet/visible and electrochemical impedance spectroscopy).