Conductivity analysis of epoxy/carbon nanotubes composites by dipole relaxation and hopping models
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- 作者：Airton Ramos ; Sergio H. Pezzin ; sergio.pezzin@udesc.br" class="auth_mail" title="E-mail the corresponding author ; Heric Denis Farias ; Daniela Becker ; Roger H. Bello ; Luiz A.F. Coelho
- 关键词：Carbon nanotubes ; Nanocomposites ; Dipole relaxation ; Hopping ; Havriliak&ndash ; Negami equation ; Electrical conductivity
- 刊名：Physica B: Physics of Condensed Matter
- 出版年：2016
- 出版时间：15 October 2016
- 年：2016
- 卷：499
- 期：Complete
- 页码：57-63
- 全文大小：1159 K
文摘
In this study it was used a numerical technique of successive approximations to estimate parameters of a conductivity model that includes the hopping process and the dipole relaxation for the purpose of describing the behavior of the conductivity measured on nanocomposites with carbon nanotubes in epoxy resin in the range of frequency of 100 Hz to 40 MHz. Two relaxation bands were detected, one with a response below 10 kHz and one above 10 MHz. For the first band, it was observed that the nanocomposites become more conductive, and its conductivity less temperature dependent, as the nanotube content increases. The second band is characterized by a large spread in relaxation time. The results show that the percolation threshold is below 0.15 vol% and that ‘ac’ hopping is the main transport process above 100 kHz, becoming dominant with respect to percolation at higher temperatures (>340 K).