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Broadband dielectric properties of onion‐like carbon/polyurethane composites
Author(s) -
Macutkevic Jan,
Banys Juras,
Kuznetsov Vladimir,
Moseenkov Sergei,
Shenderova Olga
Publication year - 2013
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201330257
Subject(s) - materials science , percolation threshold , dielectric , composite material , percolation (cognitive psychology) , composite number , relaxation (psychology) , polyurethane , microwave , carbon fibers , glass transition , conductivity , absorption (acoustics) , electrical resistivity and conductivity , chemistry , polymer , optoelectronics , telecommunications , psychology , social psychology , neuroscience , electrical engineering , biology , engineering , computer science
The results of an investigation of the broadband dielectric properties of onion‐like carbon (OLC)/polyurethane (PU) composites over a wide temperature range (300–450 K) are presented. The onset of the percolation threshold reached at 10 vol% of OLC is accompanied by drastically increased microwave absorption. The broadband dielectric properties of the composites at low loading of OLC, below the percolation threshold, are mainly governed by the α relaxation, the dynamics of the “soft” molecular segment of the PU chain. With increased OLC concentration, the glass‐transition temperature decreases and the α relaxation completely vanishes for the composite with 5 vol% OLC. As the α relaxation vanishes rapid enhancement of the mobility of the soft molecular segments in PU chains occurs and a decrease of the activation energy of electrical conductivity follows.Keywords: composites; dielectric properties; onion‐like carbon
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