Preparation of hierarchical material by chemical grafting of carbon nanotubes onto carbon fibers

A hierarchical material was produced by grafting multiwalled carbon nanotubes (MWCTNs) onto the surface of carbon fibers. A single oxidation treatment based on the combination of strong acids and ultrasounds was employed for both materials, while grafting was obtained by mean of a mild thermal treatment. The effectiveness of the oxidation treatment was evaluated by Thermogravimetric Analysis (TGA) and Fourier Transform Infrared Spectroscopy (FT-IR), while the success of the grafting was studied by TGA and Field Emission Scanning Electron Microscope (FESEM) observation. Different carbon fibers (CFs)/carbon nanotubes (CNTs) weight ratios have been used in the grafting process in order to assess how the amount of grafted CNTs can affect the final morphology of the hierarchical material. A novel hierarchical structure was observed and a mechanism for its production was proposed.