Investigating the effects of CNT aspect ratio and agglomeration on elastic constants of crosslinked polymer nanocomposite using multiscale modeling

Abstract

Multiscale modeling has been developed to calculate the Young's modulus of carbon nanotube (CNT) reinforced epoxy‐based nanocomposites. Molecular dynamics was used to construct nanocomposite models consisting of crosslinked network structure of epoxy resin as the matrix material and CNT as the reinforcement at nanoscale. Transversely, isotropic stiffness matrices were calculated using constant strain method on four cases with different CNT chiralities. Effective fiber method was employed to scale bridging from nanoscale to microscale. In multiscale calculations, various types of micromechanical methods were investigated and Halpin–Tsai formulation was selected due to its more realistic predictions. The results showed that increasing CNT aspect ratio from 1 to 1,000 results in an increase in nanocomposite Young's modulus by about three times for nanocomposite reinforced with CNT(20,0). Comparing CNT(5,0) with CNT(20,0) reinforced polymer results, suggested that increasing the CNT radius resulted in a decrease in nanocomposite moduli to about one half. Multiscale results indicated that CNT agglomeration can decrease nanocomposite Young's modulus to one‐third compared to the dispersed CNT case. Predicted results were compared with numerical and experimental results found in the literature and good agreement was observed. POLYM. COMPOS., 39:4513–4523, 2018. © 2017 Society of Plastics Engineers