The present invention relates to covalently bonded fullerene-functionalized carbon nanotubes(CBFFCNTs), a method and an apparatus for their production and to their end products. CBFFCNTs are carbon nanotubes with one or more fullerenes or fullerene based molecules covalently bonded to the nanotube surface. They are obtained by bringing one or more catalyst particles, carbon sources and reagents together in a reactor.

A process of producing a yarn, ribbon or sheet comprising nanofibers that includes infiltrating a liquid into the yarn, ribbon or sheet and evaporating the liquid from the yarn, ribbon, or sheet to strengthen the yarn, ribbon or sheet. The yarn, ribbon, or sheet can be formed by solid-state draw from a carbon nanotube forest.