Effective Conductivity of Fiber Filled Polymer Composites: Effect of
Orientation Distribution and Aspect Ratio
A. Mikdam, A. Makradi and S. Belouettar
Centre de Recherche Public Henri Tudor, 29, bd John. F. Kennedy, L-1855 Luxembourg, Luxembourg.
Polymers filled with conducting fibers are widely used in a number of important engineering
applications like automotive, aerospace and biomedical industries. The composite properties
are determined by fiber characteristics such as shape and aspect ratio as well as their
distribution, orientation and volume fraction in the polymer matrix. In the present work, we
studied the effect of the fiber’s orientation and fiber’s aspect ratio on the conductivity of fiber
filled polymer composites, using statistical continuum theory. The conductivity of the
polymer matrix is assumed to be negligible compared to the conductivity of the fibers.
Further, the fibers percolation and local interaction between the fibers and the matrix are
ignored. To take into account fibers orientation, shape and distribution, two-point and three-
point probability distribution functions are used. The effect of fibers orientation is illustrated
by comparing the effective conductivity of microstructures with oriented and non-oriented
fibers. The randomly oriented fibers result in an isotropic effective conductivity. The
increased fiber orientation distribution can lead to higher anisotropy in conductivity. The
effect of fiber’s aspect ratio on the effective conductivity is studied by comparing
microstructures with varying degrees of fiber orientation distribution. Results show that the
increase in anisotropy leads to higher conductivity in the maximum fiber orientation
distribution direction and lower conductivity in the transverse direction.