Effect of amino-functionalization on the interfacial adhesion of multi-walled carbon nanotubes/epoxy nanocomposites

Two types of multi-walled carbon nanotubes (MWCNTs) functionalized with different amino-organics, dicyanodiamide and phenylbiguanide, respectively, were achieved in this paper. The physico-chemical properties of MWCNTs before and after amino group modification were characterized by thermogravimetric analysis (TGA), Raman spectroscopy and inverse gas chromatography (IGC). The results showed that amino-functionalization changed evidently the surface properties of MWCNTs, such as the dispersive surface energy (decreased from 122.95 mJ/m2 to 18.65 mJ/m2 and 25.69 mJ/m2, respectively) and specific surface energy (decreased from 8.84 mJ/m2 to 0.56 mJ/m2 and 4.60 mJ/m2, respectively) for two functionalized MWCNTs. And then, the interfacial adhesion states of the functionalized MWCNTs/epoxy nanocomposites were investigated using scanning electron microscope (SEM) and dynamic mechanical analysis (DMA). The results also indicated that the dispersion of MWCNTs in epoxy resin and the interfacial adhesion of MWCNTs/epoxy nanocomposites were both strongly dependent on the surface physico-chemical properties of functionalized MWCNTs, and the effect of MWCNTs functionalized by phenylbiguanide with slightly higher polarity was better.

► Two types of amino-functionalized multi-walled carbon nanotubes (MWCNTs).
► Surface energy of MWCNTs decreased evidently after amino-functionalization.
► Uniform dispersion of MWCNTs obtained in epoxy due to decreased surface energy.
► Uniform dispersion and good interfacial bonding attribute to better compatibility.