. . . . "The content of the carbon nanotubes in the crosslinking solution could not be indiscriminately defined, as varying depending on the length and the thickness of the carbon nanotubes, the type thereof as to whether they are single-walled or multi-walled, the type and the amount of the functional groups that the nanotubes have, the type and the amount of the crosslinking agent, and the presence or ab" .