Enhancement in mechanical properties of multiwalled carbon nanotube-reinforced epoxy composites: Crosslinking of the reinforcement with the matrix via diamines

In this study, the effect of diamine molecular structure, attached to the multiwalled carbon nanotubes (MWCNTs), on the interfacial interactions of the MWCNTs and the epoxy matrix was studied. Pristine MWCNTs were successfully functionalized with multiple aliphatic and aromatic diamines. It has been found that, compared to aliphatic molecules, aromatic diamines can yield higher functionalization degree, due to higher activity and longer half-life of aromatic intermediates. However, at the same functionalization degree, the aliphatic ligands were more successful in reacting with epoxy chains and forming covalent bonds between the MWCNTs and the matrix. Considerable improvements were achieved in the mechanical properties of functionalized MWCNT-reinforced epoxy composites in comparison with the pristine MWCNT-reinforced composites. Fractography observations revealed distinct differences in the failure modes of reinforced composites after functionalization of the MWCNTs with diamines. POLYM. ENG. SCI., 2019. (c) 2019 Society of Plastics Engineers