Study of the mechanism of influence of carbon nanotubes surface chemistry on the mechanical properties of fiberglass

The interaction of the epoxy component of fiberglass with the surface of a nanocarbon filler (multilayer carbon nanotubes) was investigated by experimental and quantum-chemical methods. It is shown that when the multilayer carbon nanotubes are introduced into the hardener of the epoxy composition to create fiberglass, the strength of this composite correlates with the degree of oxidation of the carbon atoms of their surface. Thus, the more oxygen-containing groups are on the surface of the nanocarbon filler, the smaller the strength of the eventual fiberglass is. To explain this effect, quantum-chemical calculations of the interaction of pure and oxidized surface models of a multilayer carbon nanotube (graphene-like planes) with a hardener molecule (triethylenetetramine) were performed by quantum chemistry methods. It is found that, regardless of the size of the graphene plane, the energy of the intermolecular interaction of triethylenetetramine with the model of the oxidized outer surface of multilayer carbon nanotubes is greater than the similar value for complexes with no oxidized outer surface. The oxidized surface of the multilayer carbon nanotube adsorbs the triethylenetetramine molecule exactly by amino groups, which are reactive centers when it is reacted with the outgoing resin. Thus, the oxidized multilayer carbon nanotubes impairs the interaction of the hardener with the epoxy.