The effective complex permittivity stability in filled polymer nanocomposites studied above the glass transition temperature

F Elhaouzi,A Mdarhri,A Belfkira,C Honstettre,I El Aboudi,M Zaghrioui,M El Azhari

doi:10.1051/matecconf/201714901080

Abstract

The temperature effecton the dielectric response of nanocomposite at low frequencies range is reported. The investigated samples are formed by a semi-crystalline ethylene-co-butyl acrylate (EBA) polymer filled with three concentrations of the dispersed conducting carbon black (CB) nanoparticles. The temperature dependence of the complex permittivity has been analyzedabove the glass transition temperature of the neat polymer matrix Tg=-75°C. For all CB concentrations, the dielectric spectra follow a same trend in frequency range 100-106Hz. More interestingly, the stability of the effective complex permittivity ɛ=ɛ' -iɛ'' with the temperature range of 10-70°C is explored. While the imaginary part of the complex permittivity ɛ'' exhibits a slight decreasewith temperature, the real part ɛ' shows a significant reduction especially for high loading samples. The observed dielectric response may be related to the breakup of the three-dimensional structurenetwork formed by the aggregation of CB particles causing change at the interfaceEBA-CB.This interface is estimated bythe volume fraction of constrained polymer chain according to loss tangent data of dynamic mechanical analysis.

Highlights

The addition of nanoparticles to a polymer matrix has received much attention over several decades[1]
This study aims at the understanding the temperature dependence of theeffective complex permittivity = − of ethylene-co-butyl acrylatecopolymer (EBA) filled with spherical nanoparticles of Carbon Black (CB)
The differential thermal analysis (DTA) for elastomer matrix filled with different CB volume fractionreported in Figure 1.TheDTA curves show a small peak endothermic between 75°C and 98°C

Summary

Introduction

The addition of nanoparticles to a polymer matrix has received much attention over several decades[1]. Nanoparticles offer improved mechanical, electrical and thermal properties of polymer systems [2]. Dueto their interesting dielectric properties, nanocomposite materials with polymeric matrix have a great potential for advanced applicationssuch as electromagnetic shielding materials, dielectric resonator antennas, capacitors, electro-active materials to cite a few[3,4,5]. For example high permittivity values are needed for reducing the applied electric field to actuate electro-active materials for artificial muscle applications [6]or for increasing the energy density of capacitors [7]. The CB network restricts the motions of the polymer chains above the glass transition temperature of the polymer and increase the thermal stability as is probed by thermogravimetric analysis tests. The frequency of the applied field wastaken between 100and 107 Hz for various temperatures in the range 10–70°C

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Conclusion