Theoretical Evaluations of Stiffness Degradation Factors in Carbon-Nanotube Composites

Abstract

Though excellent performances in various properties of carbon nanotubes (CNT) are widely recognized, existing reports on the mechanical properties of their composites are not as favorable as being expected. Focusing on the tensile stiffness of CNT composites, factors that may possibly be linked with the performance degradations are evaluated. These factors include CNT distribution orientation, its aspect ratio and waviness, and CNT/resin interface properties. The micromechanics inclusion model based on Eshelby tensor, combined with Mori-Tanaka theorem is adopted in this study. The spatial orientation distribution does affect the composite stiffness, tendency of which is predictable. The aspect ratio of the CNT has relatively small effect on the stiffness, whereas the impact of waviness change is drastic, which may result in as high as 40% reduction with the waviness ratio of 0.1. The effect of interface property may depend on the way it is modeled, but the numerical results suggest that the interface bonding characteristics is one of the major issues to be focused on.