The Research On The Carbon Nanotubes' Surface Modification And The Unilateral Reinforcing Composites

Hyperbranched poly(amidoamine) was in situ "grafted from" Multi-Walled Carbon Nanotube (MWCNT) surfaces having amino groups (initiator sites) which were prepared via reaction between toluene 2, 4-diisocyanate and carboxylated carbon nanotubes followed by addition of ethylenediamine. Hyperbranched poly(amidoamine) (PAMAM) was propagated from the carbon nanotube surfaces by successive repetition of (1) Michael addition of methyl acrylate to surface amin0o groups and (2) amidation of the resulting esters with ethylenediamine. FT-IR, Raman spectroscopy, UV-Vis, TGA and FE-SEM confirmed the reactions and their products. Using at least one generation of PAMAM, the modified MWNTs were stable for long periods (i.e. more than 1 month) in water. Epoxy/multi-walled carbon nanotubes (MWNTs) composite fibers (about 50μm diameter) were prepared using coagulation spinning in aqueous media. Optical microscopy confirmed the good dispersion of PAMAM modified MWNTs compared to the pristine MWNTs in EP. The PAMAM modified MWNTs also conferred high toughness and good matrix adhesion to the resulting fibers. Flow-induced alignment leads to a preferential orientation of the carbon nanotubes. The mechanical and thermodynamic propreties are also improved by the addition of functional MWNTs.