Multi-walled carbon nanotubes (MWCNT) have been treated by mixed acids, resulting in the formation of many carboxyl groups on their sides. With the action of N,N'-dicyclohexylcarbodiimide, p-aminobenzenesulfonic acid could be grafted to MWCNT. Taking the strong sulfuric acid as the sulfonation agent, sulfonated poly(ether ether ketone) (SPEEK) was prepared under room temperature. SPEEK/grafted- WMCNT composite film could be prepared by a solution blending method. The structure and properties of the modified MWCNT were characterized by FT-IR, TGA, TEM and Raman spectra. The FT-IR spectrum showed that the amino group of p-aminobenzenesulfonic acid reacted with the carboxyl on the sides of the MWCNT, and the process created an amide group. The TGA curves showed that the weight ratio of the organic group grafted on the MWCNT surfaces reached 40%. The Raman spectrum showed that the ratio of I_D/I_G changed very slightly, which indicated that the content of the graphite structure of the MWCNT was not changed basically. The measurement of mechanical properties of the composite film showed that the grafted-MWCNT could increase the tensile strength of the film.

Key words: multi-walled carbon nanotube, p-aminobenzenesulfonic acid, superficial modification, N,N'-dicyclohexylcarbodiimide