Temperature Effect on Dielectric Properties of Heterogeneous Material Based on Carbon Black Loaded Copolymer Nanocomposite

摘要

In this work, we report an experimental study of the thermal and electrical properties of heterogeneous materials based on ethylene butylacrylate copolymer filled with carbon black nanoparticles. For this study, a series of samples were prepared with filler fractions above the percolation threshold. Their thermal characterization was performed using differential scanning calorimetry, thermogravimetric analysis, and differential thermal analysis which allowed to observe significant changes in the spectrum at melting and degradation temperatures of composites. Dielectric measurements were carried out in the frequency domain 40 Hz-2 MHz and temperature domain 300-400 K. Using the impedance spectrum, it has been found that the Cole-Cole model is capable to describe quantitatively the experimental data from which we extract the relaxation time and exponent that gauges the broadening of the loss spectrum. The obtained values of α exponent are near zero, suggesting a behavior close to a model of single relaxation time. Furthermore, the relaxation time versus temperature follows an Arrhenius behavior for temperatures above the melting point. The activation energies and the pre-exponential factors decrease with carbon black concentrations, indicating that the relaxation mechanism does not result simply from thermally activated dipolar interactions, but it is a collective cooperative effect of the mesostructured particles.