Electrical conductivity of polyester filled with carbon nanotubes composites have been studied from 240 to 380 K in the frequency range from 100 Hz to 1 MHz as a function of the filler volume fraction above the percolation threshold. The frequency dependence of the electrical conductivity obeys the universal dynamic response. Positive temperature coefficient in resistivity and negative temperature coefficient in resistivity phenomena were observed at temperatures below and above the glass transition respectively. It was found that the mechanism responsible for the changes in resistivity is predominantly due to the tunneling effect. Positive temperature coefficient in resistivity intensity was also exploited which is strongly dependent on the carbon nanotube content.
We have investigated the electrical properties of carbon black (CB) loaded in ethylene butylacrylate copolymer composite (EBA) in the frequency range between 10<sup>2</sup> and 10<sup>4</sup> Hz and temperature range between 153 and 353 K. The frequency dependence of electrical data that have been analyzed in two frameworks: the electrical modulus formalism with the Kohlrausch-Williams-Watts stretched exponential function (KWW) and the electrical conductivity by using the Jonscher’s power law in the frequency domain. The stretching exponent β<sub>KWW</sub> and n are found to be temperature independent for all CB fractions and to be decreased when the CB volume concentrations loaded in copolymer matrix increases. It is found that the activation energy obtained by the modulus method is in good agreement with that obtained by the DC conductivity in the power law which is independent on the CB contents that exist in the copolymer matrix, suggesting that these particles do not interact significantly with the chain segments of the macromolecules in the EBA copolymer
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