Electromechanical Behavior of Carbon Nanotube Turfs Under Torsion

This paper describes the electromechanical behavior of carbon nanotube (CNT) turfs when a torque is applied. High aspect ratio (~3.83) cylindrical CNT turfs were grown by a three-zone temperature chemical vapor deposition (TZT-CVD). A distinctive apparatus is developed to apply a torque on the CNT turf and measure the torsional angle simultaneously. Electrical resistance of CNT turf can be recorded during the torsional process. From the experimental results, wrinkles are observed on the exterior of CNT turfs when a torque is applied. The electrical resistance will rise with the increasing shear strain and will rise suddenly after torsional angle of 80°. It indicates that the structure of CNT turf can sustain large shear strain before torsional angle of 80°. In the torsional process, turf structure will go through strain, rupture, and break. Also, the critical buckling angle always occurs at the resistance change exceeding 5%. From the resistance changes, the buckling time and the buckling angle can be forecast. Compared with individual CNT, the CNT turf possesses relatively low critical shear strength of several MPa.