An interphase design strategy for multifunctional polymer nanocomposites using multiscale method

摘要

In this study, a multiscale model which integrates molecular dynamics (MD) simulation and finite element (FE) analysis has been developed to design multifunctional polymer nanocomposites and their effective interphase. Both the global stiffness of the polymer nanocomposite model and the internal stress distribution on the nanofiller surface during mechanical loadings were quantitatively characterized. Through MD simulations, crosslinked epoxy resin (crosslinking ratio: 0.45) and nano-sized filler (spherical SiC and zigzag single walled carbon nanotube) embedded epoxy nanocomposite models were prepared with full atomistic detail. For each model, uniaxial tensile tests were carried out to obtain the elastic behavior of the nanocomposites and the strain energy distribution in the vicinity of a nanofiller surface. Meanwhile, a three-dimensional FE model of a three-phase was prepared, consisting of a nanofiller, polymer networks adsorbed on the nanofiller surface (interphase), and polymer networks non-adsorbed on the nanofiller surface (bulk matrix). The unknown mechanical response and thickness of the interphase were numerically characterized through homogenization and deformation energy matching to that of the full atomic molecular model, respectively. The present multiscale method, therefore, yields an effective region of the interphase as well as its mechanical properties. The suggested multiscale model accurately predicts virial local stresses at both the interphase and bulk matrix regions of the full-atomic model and explains the reinforcing mechanism at the interphase region.