Multi-Walled Carbon Nanotube Reinforced Polyimide Composites

Polyimides have a wide range of uses such as aeronautical applications of fuel cells, optics and electronic materials industry due to their outstanding thermal, mechanical and chemical properties. In this study, it was aimed to prepare composite polyimide films with amine-tethered multi-walled-carbon nanotubes (MWCNT). Firstly, to produce amine functional groups onto the surface of MWNCTs, MWCNTs were reacted with H2SO4/HNO3, thionyl chloride and ethylenediamine. Then polyamic acid solution was prepared from 3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) and, 4′-oxydianiline (ODA). The functionalized carbon nanotube was added to the PAA solutions with certain amounts (1, 3, 4, 5 and 6 wt. % followed by stepwise thermal imidization. The thermal stability of the composite polyimide films were enhanced with addition of modified-carbon nanotube due to covalent interaction between polyimide based matrix and modified-carbon nanotube as a result of the imidization reaction. The addition of MWCNT increased the Tg of the BTDA-ODA-6% MWCNTs polymide film from 275 to 304 °C with respect to the BTDA-ODA polyimide film. In addition, the mechanical properties of the films were improved. While the modulus of BTDA-ODA film was found as 743 MPa, with the introduction of MWCNT the modulus of BTDA-ODA-6% MWCNTs was increased up to 1119 MPa.