Silane grafted MWCNT/polyimide composites – Preparation, morphological and electrical properties

Precursor of polyimide, polyamic acid has been prepared by reacting 4,4′-oxydianiline with 3,3′,4,4′-benzophenone tetracarboxylic dianhydride. Acid modified multiwall carbon nanotubes (MWCNTs) were grafted with 3-isocyanato-propyltriethoxysilane. Silane grafted MWCNTs were then mixed with the polyamic acid and heated to 300 °C to form a carbon nanotube/polyimide composite. During the imidization processes, the silanes on the MWCNT surface reacted with each other. TEM microphotographs shows that the silane grafted MWCNTs were connected. The composite material possesses an interpenetrating network in which polyimide molecules were interpenetrated into the MWCNT network. The electrical resistivity of silane grafted MWCNT/polyimide decreased very significantly compared to those only containing acid treated MWCNTs for the same loading with MWCNTs.