Propiedades Dieléctricas de Materiales Compuestos de BaTiO3 en una Matriz Polimérica

Abstract

En este trabajo se analiza el comportamiento dieléctrico de materiales compuestos (resina epoxi -titanato de bario) en función de la cantidad de titanato de bario agregado. El material compuesto se obtuvo, previa mezcla de ambos componentes, por colada y posterior curado a 100ºC. Los resultados del análisis dieléctrico mostraron que los materiales poseían altas constantes dieléctricas a pesar de las altas porosidades observadas durante el análisis microestructural de las muestras mediante Microscopía Óptica. El comportamiento dieléctrico pudo ser representado mediante el modelo de Liechtneker.

The dielectric behaviour of composite materials (epoxy resin – barium titanate) was analysed as a function of ceramics content. Epoxy and Nb2O5-doped BaTiO3 were chosen because of their good dielectric properties. The ceramic was milled in isopropilic medium using a planetary mill with ZrO2 balls for 90 min to obtain better dispersion during the mixing. The composites were made mixing both components and pouring into suitable glass moulds. After that, the system was cured at 100ºC during 2 hours. Dielectric measurements were performed from 1 KHz to 1 MHz. Density was measured by the Arquimedes method and microstructure was characterised by Optical Microscopy. Particles size distributions were determined and lattice parameters were characterised by X-Ray Diffraction, while the resin was characterized by differential calorimeter analysis (DSC). It was observed that the transition temperature (Tg) of pure epoxy was 100ºC. Nevertheless their big porosity (»10%), it was found that resultant materials had high dielectric (up to constants »20e0) and a strong dependence with the filler concentration. Microestructural analyses showed a good dispersion of ceramic particles in composites, but with smalltrails of agglomerations. Electrical relaxation generated by resin dominions was detected in the composite influenced by temperature (principally near Tg) and frequency through Debye-type process. Many models were used to describe the material behaviour, however it only could be fitted through Liechtneker.