Multiscale modeling of the effects of nanoscale load transfer on the effective elastic properties of unfunctionalized carbon nanotube–polyethylene nanocomposites

A multiscale model is proposed to study the macroscale bulk elastic material properties under the influence of interfacial load transfer at the nanoscale in carbon nanotube–polyethylene (CNT–PE) nanocomposites. Molecular dynamic (MD) simulations are performed to characterize the nanoscale load transfer through the identification of representative nanoscale interface elements which are studied parametrically in terms of the length of the polymer chains, the number of the polymer chains and the 'grip' position. Once appropriate scales of these parameters are deemed to yield sufficiently converged results, the representative interface elements are subjected to normal and sliding mode simulations in order to obtain the force–separation responses at 100 and 300 K for unfunctionalized CNT–PE interfaces. Cohesive zone traction–displacement laws are developed based on the force–separation responses obtained from the MD simulations and are used in continuum level models to determine the influence of the interface on the effective elastic material properties of the nanocomposites using analytic and computational micromechanics approaches. It is found that the inclusion of the nanoscale interface in place of the perfectly bonded interface results in effective elastic properties which are dependent on the applied strain and temperature in accordance with the interface sensitivity to those effects, and which are significantly diminished from those obtained under the perfect interface assumption. (paper)