Proceedings of COMP07:
6th International Symposium on Advanced Composites
16-18 May, 2007, Corfu, Greece

COMP2007-021

MICROMECHANICS MODELING OF THE MULTI-FUNCTIONAL NATURE OF
CARBON NANOTUBE-EPOXY NANOCOMPOSITES: EFFECTIVE ELASTIC
THERMAL AND ELECTRICAL PROPERTIES

Dimitris C. Lagoudas
Aerospace Engineering Department
Texas A&M University
Gary D. Seidel
Aerospace Engineering Department
Texas A&M University

ABSTRACT
Continuum level micromechanics approaches are employed herein to study the effects of interphase
regions on the elastic, electrical, and thermal properties of carbon nanotube reinforced polymer matrix
composites. The interphase regions are seen as a result of carbon nanotube-polymer interactions which
can be dependent on nanotube functionalization, or lack thereof, and have thicknesses on the order of
carbon nanotube radii or larger. Additional near zero thickness interphase regions are identified as means
of phenomenologically introducing nanoscale interface effects such as the Kapitza resistance and electron
hopping on the thermal and electrical conductivities, respectively. Emphasis is placed on the use of the
generalized self-consistent composite cylinders (GSC-CC) approach in the determination of the effective
elastic constants and electrical and thermal conductivities of aligned carbon nanotube-epoxy
nanocomposites. The GSC-CC approach allows for the calculation of the appropriate mechanical,
electrical and thermal concentration tensors for coated, hollow cylinders where one can not directly take
advantage of Eshelby solutions. These concentration tensors are then used in a micromechanics averaging
approach towards determining the effective Young’s modulus, shear modulus, and thermal and electrical
conductivity of nanocomposites consisting of randomly oriented nanotubes in epoxy. The results are
compared to experimental data available in the literature, and the impact of the interphase regions on the
percolation limits for electrical and thermal conductivity are discussed.