Preparation of amine-modified multiwalled carbon nanotubes and their use in composites

Multiwalled carbon nanotubes (MWCNTs) were modified by a graft reaction of diamines with different chain lengths, such as ethylenediamine(EDA), hexamethylene diamine(HMDA) and decamethylene diamine(DMDA). FTIR, Raman spectroscopy, XPS and TEM were used to characterize their chemical structure. XPS indicated that the molar content of N on the surface of MWCNTs-EDA, MWCNTs-HMDA and MWCNTs-DMDA reached 3.52%, 4.18% and 2.88% respectively under the same reaction conditions. The dispersion of MWCNTs in organic solvents before and after the modification was measured semi-quantitatively using UV-Vis spectra and a Turbiscan analyzer. It was found that the amino-modified MWCNTs improved their dispersion in polar solvents and MWCNTs-HMDA had the best dispersion stability. MWCNTs-HMDA were introduced into a traditional carbon fiber reinforced epoxy system to prepare three phase composites which showed remarkably improved flexural and impact strengths.