Tensile strength of spinnable multiwall carbon nanotubes

Individual multi walled Carbon Nanotubes (CNTs) exhibit exceptional strength and stiffness. However, large scale constructs of directly spinnable CNTs (such as yarns) has reached only a few percent of their potential. To improve their performances in such scale, it is important to understand the stress-strain characteristics and failure modes of individual CNTs. This paper reports the experimental tensile strength of spinnable multiwalled carbon nanotubes (MWNT). These experiments were conducted using a nano tensile testing stage inside Scanning Electron Microscope (SEM) chamber. An Atomic Force Microscope (AFM) tip with known force constant was used as a nano manipulator and as s force transducer to measure the desired mechanical properties. Transmission Electron Microscope (TEM) images were used to accurately measure the diameter of CNT samples. The fracture strength was calculated using the determined applied force and the diameter of the CNT. Fracture strength in relations to number of failed walls, pullout (sword/sheath) behaviour and angle of stress are studied. It was found that the tensile strength of the tested spinnable CNTs were at least 20 to 90 Gpa with a mean value of 48 Gpa considering a solid cross sectional area. © 2011 Published by Elsevier Ltd.