Theoretical Predictions of the Interfacial Stress Transfer in Nanotube-Reinforced Polymer Nanocomposites by Using a Strain-Hardening Shear-Lag Model

Interfacial load transfer inside nanofiber-reinforced polymer nanocomposites plays a vital role in capitalizing on the extraordinary mechanical properties of the added nanofibers and in governing their bulk mechanical performance. In this paper, we investigate the load transfer characteristics of nanotube–polymer interfaces by using a micromechanics shear-lag model that takes into account the elastoplastic properties of polymer matrices. Closed-form analytical solutions of the interfacial shear stress distribution profile are derived. The failure of the nanotube–polymer interface and the pull-out force are analyzed using this model based on recently reported nanomechanical single-nanotube pull-out experiments that were conducted on carbon nanotube and boron nitride nanotube polymer interfaces. The theoretical predictions are in good agreement with experimental measurements. The findings from this work are useful to a better understanding of the interfacial load transfer characteristics of nanofiber-reinforced polymer nanocomposites and ultimately contribute to the optimal design and performance of lightweight and high-strength nanocomposite materials. The presented micromechanics model and the analytical solutions can be extended to study the interfacial stress transfer inside 1D nanofiber-reinforced metal and ceramic nanocomposites as well as of 2D material based composites and devices.