(58d) Molecular Simulation Study of Nanoscale Heterogeneities In Epoxy-Carbon Nanotube Nanocomposites

Reinforcement of epoxy matrices by inclusions such as carbon nanotubes (CNTs) has great potential for enhancing the mechanical properties of the epoxy. However, experimentally observed property enhancement is often much lower than that predicted by the theory.  This has been attributed to factors such as inefficient load transfer between carbon nanotubes and the surrounding epoxy matrix as well as the aggregation of carbon nanotubes.  In this work, we have used atomistic simulations to study the effect of CNT aggregation on the nanocomposite properties. 

The specific epoxy system studied consists of diglycidyl ether of bisphenol A (DGEBA) that is cured by diamino-diphenyl sulfone (DDS), and pristine CNTs are used as fillers.  We create atomistically detailed structures of these epoxy-CNT nanocomposites by polymerization of the reaction mixture in the simulation box.  All of the simulations are carried out using the LAMMPS (Plimpton, S. Journal of Computational Physics 1995, 117, 1-19) package.  We will present a detailed study of the effect of CNT aggregation in the system on the structural and thermal properties of the nanocomposite.  The origin of the observed heterogeneities in the structure will be explained using free energy calculations.