Actuation of aligned Carbon Nanotube Arrays

Kurzfassung

The active behaviour of carbon nanotubes (CNTs) can be observed when CNTs are positioned within an electric field and immersed into an electrolyte. Several explanations are given, ranging from nanoscopic effects such as carbon bonds weakening by electron doping or atomistic double layer-induced interaction of electron orbitals. Also macroscopic effects such as volume changes as result of ion intercalation, gas generation or electrostatic effects have been proposed. In this paper experiments aligned, continuous CNT-arrays of macroscopic dimensions (3mm) are tested electromechanically in contrast to former tested CNT-papers. Their behaviour is tested at different conditions and by using different electrolytes within a modified tensile testing machine. The tests reveal almost no condition dependency, which can be explained by the presence of the neat carbon bonds. The specimen orientation and the test approach exclude macroscopic effects such as volume effects by ion diffusion. The measured free strain and the behavior of the force can be assigned to an elongation of the neat carbon structure. Furthermore, asymmetric progressions of the results at negative and positive potentials seem to be related to ion-interaction. It must be assumed that superimposing effects are measured.