Abstract
Polymer composites filled with conductive fillers can demonstrate ultrahigh effective dielectric permittivity, which is generally attributed to an enhanced Maxwell-Wagner-Sillars interfacial polarization associated with the formation of microcapacitor networks. Here, we explore a composite of the ethylene-propylene-diene elastomer with carbon-black (CB) nanofillers and investigate its dielectric response over wide ranges of temperature and frequency. The dielectric relaxation exhibits atypical (counter-Arrhenius) temperature dependence, contradicting the widely assumed interfacial polarization mechanisms. It is shown that the relaxation/polarization is actually determined by electron displacement─primarily via e-conduction and tunneling within CB clusters─and that the composites' dielectric response can be quantitatively correlated with the CB cluster morphology via a set of scaling laws. Considering the selected composite as a paradigmatic system, the physical origins of the dielectric relaxation and the associated scaling relations seem to be generally applicable and expected to also pertain to other dielectric polymer/conductive-filler composites near percolation.
Original language | English (US) |
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Pages (from-to) | 7596-7604 |
Number of pages | 9 |
Journal | Journal of Physical Chemistry C |
Volume | 126 |
Issue number | 17 |
DOIs | |
State | Published - May 5 2022 |
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- General Energy
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films