A self-entanglement mechanism for continuous pulling of carbon nanotube yarns

We report an in situ electron microscopy study of pulling mechanism of super-aligned carbon nanotube (CNT) arrays grown by chemical vapor deposition. The formation of entangled structures at the ends of CNT bundles during pulling is very critical for the pulling process. By cutting the top and bottom layers of both pullable and not pullable CNT arrays, we confirm that the structures at the top or bottom surfaces of the as-grown CNT arrays are not the dominant reason to ensure the continuous pulling process. We have observed the formation of entangled structures when the pulling process approaches the bottom and top ends of the CNT arrays. These entangled structures are responsible for maintaining the continuity of pulling CNTs.