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Electrical properties of carbon nanotubes-based epoxy nanocomposites for high electrical
conductive plate were investigated. Dispersion and incorporation mechanism between two
conductive fillers with different sizes (CNTs and Graphite) in the polymer matrix are the key factors
in the fabrication of high electrical conductivity plate. Different variation of carbon nanotubes
(CNTs) (1~10 wt %) and Graphite (G) (60 ~ 69 wt %) loading concentration were added into the
epoxy resin. Dispersion of CNTs and G in epoxy resin were conducted by the internal mixer with a
Haake torque rheometer. The mixture of G/CNTs/EP was poured into the steel mold, and
G/CNTs/EP nanocomposites had been fabricated through compression molding. The electrical
conductivity of nanocomposites in terms of variation of G and CNTs concentration were measured
by the four point probe for in a plane electrical conductivity. The results revealed that addition of
G/CNTs and increasing curing temperature are effective ways to produce high electrical conductive
nanocomposites. The highest electrical conductivity was reached on 104.7 S/cm by addition 7.5
wt% of CNTs. Dispersion quality of G and CNTs in the epoxy matrix was observed on the fractured
surface by scanning electron microscopic.
Electrical conductive composite made of insulating polymer matrix and conductive filler have found
numerous applications and are used as heating device, and for electromagnetic shielding. The
electrical conductivity of composite material with a polymeric matrix is mainly related to the weight
percentage of the conductive filler, the size and shape of its particles and also to other factors such
as adhesion between the host phase and the matrix, the method of processing and possible
interactions between the conductive and non conductive phase[1]. The major advantages of the
material are lower cost, lightweight, and easily machined, with good corrosion resistance, relatively
good mechanical properties, and good gas tightness while the major disadvantage is that polymers
have extremely low electrical conductivity, so excessive conductive filler had to be incorporated. In
this case, it is difficult to get high conductivity and sufficient mechanical properties simultaneously.
To get high electrical conductive plate, the conductive filler loadings greatly exceed percolation
threshold concentrations, and approach or even surpass critical pigment volume concentrations
(CPVC) of 50-70 % in volume [2]. At the percolation threshold concentration, an interconnecting
path of conductive graphite particle forms and extend throughout the entire sample thickness, thus
enabling electrons to “percolate”. The electrical resistance decreases by many orders of magnitude
as the material goes through an insulator–conductor transition. At higher graphite loadings such as
that at the CPVC, there is no enough polymer binder to carry the graphite particles. Many more
percolation pathways form for enhanced conductivity, but the materials become to be porous and
weak [3]. As a result, composite plate materials with high graphite content are extremely brittle, and
have poor gas barrier properties. Note that above the CPVC, the material has an insufficient carrier
polymer and behaves like a solid; consequently, the material does not flow and fill the mold well
during processing. Consequently, the filler loadings of the composites should be at graphite levels
Advanced Materials Research Vols. 264-265 (2011) pp 559-564
Online available since 2011/Jun/30 at www.scientific.net
© (2011) Trans Tech Publications, Switzerland
doi:10.4028/www.scientific.net/AMR.264-265.559
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,
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