Dielectric Behavior of Epoxy/BaTiO₃ Composites Using Nanostructured Ceramic Fibers Obtained by Electrospinning

Abstract

Composite materials made of epoxy resin and barium titanate (BT) electrospun nanostructured fibers were prepared. BT fibers were synthesized from a sol based on barium acetate, titanium isopropoxide, and poly(vinyl pyrrolidone). The fibers were heat-treated at different temperatures and characterized by X-ray diffraction, scanning electron microscopy (SEM), and Raman spectroscopy. Mats of BT fibers heat-treated at 800 °C were embedded in epoxy resin into suitable molds. The composites were characterized by SEM, and dielectric measurements were performed by means of dielectric spectroscopy. The dielectric permittivity and dielectric modulus of epoxy resin/BT-fiber composites were measured for two types of samples: with the electrodes parallel and perpendicular to the BT fiber layers. Interestingly, composite samples with electrodes perpendicular to the fiber layers and a BT content as low as 2 vol % led to dielectric permittivities three times higher than that of pure epoxy resin.

Dielectric permittivity calculation of composites based on electrospun barium titanate fibers

“…Figure 3 fibers was discussed in a previous work [24]. The permittivity as a function of frequency for BaTiO 3 fiber layers/air composites is shown in Figure 6.…”

“…For the dielectric characterization of composites, silver electrodes were painted on different faces of the composite samples (dimensions 1x1x10 mm), in order to obtain two different configurations of electrodes (parallel or perpendicular) regarding to the fiber mat layers, as shown in Figure 2, (as already described in Ávila et al [24]). In order to predict the dielectric properties of the Epoxy/BaTiO 3 composites, equation…”

“…Composites can be prepared in many different ways, leading to a large variety of morphologies, which strongly influence the macroscopic behavior [19]. Recently, new polymer composites using electrospun BaTiO 3 fibers have been reported with promising results [20][21][22][23][24]. Ceramic fibers are attractive because of the increased anisotropy, improved flexibility and strength over monolithic ceramics.…”

“…For instance, the potential of nanostructured composites that include BaTiO 3 fibers in their compositions has been demonstrated by applications in miniaturized electronic devices and sensors [21,23,25]. Concerning different device configuration 3 possibilities, a significant increase in the composite dielectric permittivity was obtained depending on the orientation of fibers inside the matrix [24].…”

“…In a previous work [24], a new kind of polymer/ceramic fibers composite using BaTiO 3 fiber layers in parallel and perpendicular configurations with regard to the electrodes was introduced. One of the problems in predicting the effective dielectric permittivity of polymer/ceramic composites is the fact that the dielectric permittivity of the ceramic filler is not available.…”