Proceedings of IMECE2007
2007 ASME International Mechanical Engineering Congress and Exposition
November 11-15, 2007, Seattle, Washington, USA

IMECE2007-42339

ELECTRICAL AND THERMAL CONDUCTIVITIES OF CARBON NANOTUBE-EPOXY
COMPOSITES: MODELING AND CHARACTERIZATION

Gary D. Seidel, Yordanos Bisrat, Dimitris C. Lagoudas

Aerospace Engineering Department
Texas A&M University
College Station, Texas 77843-3141


ABSTRACT
The motivation of this work is to develop adhesive layers
from epoxy based nanocomposites using carbon nanotubes
(CNTs) for use in thermal management applications in microelectronic
devices. The focus of the experimental characterization
is to measure the enhancement of electrical and thermal conductivities
of polymeric nanocomposites consisting of XD grade
CNTs as a function of a range of weight percentages. Comparison
of the results obtained for these CNT-epoxy nanocomposites
are made with other nanocomposite results from the literature
and with initial micromechanics modeling efforts. The
micromechanics model is centered on the use of the generalized
self-consistent composite cylinders method in conjunction
with multi-phase averaging methods, and is employed to predict
the effective electrical and thermal properties of nanocomposites
with randomly oriented CNTs, where the hollow nature of
the CNTs and the possible presence of interphase regions precludes
the direct use of the Eshelby solution. Interphase regions
are identified to phenomenologically introduce nanoscale effects
such as the thermal Kapitza resistance and electron hopping.
It is observed that, as a result of the different character of the
nanoscale effects associated with electrical and thermal properties,
nanotube-polymer nanocomposites demonstrate a percolation
behavior in electrical conductivity not observed in thermal
conductivity.