Electrical conductivity, strength and microstructure of carbon nanotube multi-yarns

Since the inception of carbon nanotubes (CNTs), there has been a great deal of effort in developing CNT applications. One possible application is to utilize CNT yarn(s) in structural and electrical devices. This study investigated 13 different variations of CNT multi-yarns. The multi-yarns were evaluated and compared in terms of tensile load behavior and electrical conductivity as well as interrelationship and interdependence of these two properties with physical parameters and micro-structural features. The electrical conductivity of the CNT multi-yarn is not affected by the apparent diameter, number of yarns, tex or density, but instead by its interior compactness and acid treatment. The construction of single CNT yarn or multi-yarn can be tailored to achieve stress-strain behavior ranging from a stiff to ductile or highly non-linear behavior. CNT single-yarn is stronger and stiffer than a multi-yarn. The decrease in strength and stiffness of a multi-yarn does not depend directly upon the number of yarns. Thus, larger diameter CNT multi-yarn can be developed with less or no reduction in tensile properties in comparison to that of CNT array. Finally, this study's observations provide useful information for further improvement of the tensile and electrical conductivity performance of CNT yarn(s). Published by Elsevier Ltd.