Preparation of novel polyimide nanocomposites with high mechanical and tribological performance using covalent modified carbon nanotubes via Friedel-Crafts reaction

Novel polyimide nanocomposites with excellent mechanical and tribological properties were achieved using amine functionalized multi-walled carbon nanotubes (MWCNT-NH2). MWCNT-NH2 was successfully obtained through Friedel-Crafts acylation and nitroreduction. PI nanocomposites with different contents of MWCNT-NH2 were prepared via in-situ polymerization. In contrast with the properties of pure PI or PI/MWCNT blends, the tribological properties, mechanical properties, and thermal performance of PI/MWCNT-NH2 nanocomposites were evidently improved due to the homogeneous dispersion of MWCNT-NH2 in PI matrix as well as the strong interfacial covalent bonds between MWCNT-NH2 and the PI matrix. Notably, it was demonstrated that the PI/MWCNT-NH2 nanocomposite adding with 0.7 wt% MWCNT-NH2 exhibited the best tribological properties in consideration of the friction coefficient (0.310) and wear rate (2.234 × 10−4 mm3/Nm) under dry sliding condition. Furthermore, the resulting PI/MWCNT-NH2 nanocomposites possessed the combined excellent tribological and mechanical properties, evidencing their potential applications in the field of the friction materials and other high-performance areas.