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The order addition effect of carbon black/graphite on the electrical properties of rubber composites
Author(s) -
Mansour S. A.,
ElSalam M. A.,
Moharram A. H.,
Hussein M.,
AlAgel Faisal A. M.
Publication year - 2012
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.36841
Subject(s) - materials science , carbon black , composite material , graphite , natural rubber , dielectric , electrical resistivity and conductivity , temperature coefficient , conductivity , crystallinity , thermal conduction , thermal conductivity , chemistry , optoelectronics , electrical engineering , engineering
Acrylonitrile‐butadiene rubber (NBR) filled with two types of fillers [high abrasion furnace carbon black (C), and graphite (G)] is made to find out the effect of order addition of C and G on the electrical conductivity of the composites. The temperature and frequency dependence of the (dc and ac) conductivity and dielectric constants have been measured. The values of the thermal expansion and thermal conduction coefficient of NBR rubber lead to the difference in I – V characteristics between CB‐ and G‐NBR rubber composites during the measurement. When graphite is first added to NBR, the electrical conductivity of (GC 20‐20 ) matrix is larger than that of the (CG 20‐20 ) matrix, whereas the carbon black is added first. At low temperature ( T < 90°C), the higher values of the dielectric constant (ε′) for the sample GC 20‐20 compared with that of the CG 20‐20 sample is due to the conducting nature and structure of graphite, whereas the carbon shows less crystallinity and conductivity than graphite. Opposite behavior is noticed at temperature higher than 90°C. The dc conductivity of all composites increases with increasing temperature exhibiting a positive temperature coefficient of conductivity (PTCσ). The conductivity at high temperatures region is controlled by the thermal excitation transport mechanism, whereas at low temperatures region is dominated by tunneling process. The increase in the value of dielectric constant (ε′) with temperatures for the sample GC 20‐20 compared with the sample CG 20‐20 is due to the conducting nature and structure of graphite, and the carbon less crystalline than the graphite. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012