Investigating the effects of resin crosslinking ratio on mechanical properties of epoxy-based nanocomposites using molecular dynamics

Abstract

Finite-element method and micromechanical formulations have been used to predict mechanical properties of epoxy-based nanocomposites in recent years. The results of these investigations, however, show large scatters and do not agree well with experimental measurements. The differences in the results may be due to the fact that these approaches do not take some important material parameters into account, such as resin crosslinking ratio, nanotube/matrix interface, and nanotube agglomeration. The main objective of this article is to investigate the effects of resin crosslinking ratio on mechanical properties of epoxy-based nanocomposites using molecular dynamics (MD). First, models of partially cured epoxy resin were created in Materials Studio software to determine resin properties at different crosslinking ratios. Next, one sample of neat epoxy and four samples of nanocomposite with different resin crosslinking ratios were modeled using MD. These models were analyzed using constant strain method to determine mechanical properties of the five samples. Also, the effects of crosslinking ratio on nanocomposite density were investigated. The simulation results show that nanocomposite Young's modulus increases with resin crosslinking ratio. Resin crosslinking ratio, however, did not have a significant effect on nanocomposite density. Further, molecular simulation results were compared with rule of mixtures and Mori–Tanaka predictions. In addition, the results were compared with those found in the literature and good agreement was observed between the results. POLYM. COMPOS., 38:E433–E442, 2017. © 2016 Society of Plastics Engineers.