The order addition effect of carbon black/graphite on the electrical properties of rubber composites

• Published in: Journal of applied polymer science 2012-10, Vol.126 (2), p.593-600
• Main Authors: Mansour, S. A., El-Salam, M. A., Moharram, A. H., Hussein, M., Al-Agel, Faisal A. M.
• Format: Article
• Language: English
• Subjects: a.c conductivity; Abrasion; Abrasion resistance; acrylonitrile-butadiene rubber; Applied sciences; Carbon; Carbon black; Composites; Dielectric constant; dielectric properties; Exact sciences and technology; Forms of application and semi-finished materials; Graphite; Materials science; Polymer industry, paints, wood; Polymers; processing sequences; Resistivity; Rubber; Studies; Technology of polymers; Temperature
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.36841

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 (GC20‐20) matrix is larger than that of the (CG20‐20) 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 GC20‐20 compared with that of the CG20‐20 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 GC20‐20 compared with the sample CG20‐20 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