Alternating current electrical conductivity of high-density polyethylene-carbon nanofiber composites |
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Authors: | L -X He and S -C Tjong |
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Institution: | 1.Department of Physics and Materials Science,City University of Hong Kong,Kowloon,Hong Kong |
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Abstract: | High-density polyethylene (HDPE)-carbon nanofiber (CNF) composites with good dispersion of fillers in the polymer matrix were
melt-compounded in a Haake mixer. The dependences of the alternating current conductivity of such nanocomposites on the filler
content, temperature, and DC bias were investigated. The results showed that the electrical conducting behavior of HDPE-CNF
nanocomposites can be well characterized by the direct current conductivity ( sDC \sigma_{{{\rm DC}}}^{} , characteristic frequency (fc) and critical exponent (s . It was found that sDC \sigma_{{{\rm DC}}}^{} of percolating HDPE-CNF nanocomposites increases with increasing filler concentration and follows the scaling law of percolation
theory. Increasing temperature caused a reduction of sDC \sigma_{{{\rm DC}}}^{} , leading to the occurrence of positive-temperature-coefficient effect near the melting temperature of HDPE matrix. Application
of DC bias led to an increase of sDC \sigma_{{{\rm DC}}}^{} due to the creation of additional conducting paths within the polymer composites. The characteristic frequency generally
followed the same tendency as sDC \sigma_{{{\rm DC}}}^{} . The s values of percolating composites were slightly higher than those predicted by the percolation theory, indicating the presence
of tunneling or hopping conduction in these composites. |
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