Investigation into microstructure of carbon nanotube multi-yarn

Structural analysis at the nano and micro scale was performed on a carbon nanotube (CNT) multi-yarn. The yarns were made by a process of drawing CNTs into a ribbon and twisting the ribbon into a yarn. Scanning electron microscopy (SEM) was used to view the exterior of the yarn. Polarized microscopy was used to examine details of the 1-yarn, and it also identified ribbon–ribbon boundaries. Further examination of interior structure was done by NanoCT scans which showed that folding of the ribbons had occurred causing complicated structures. The interior folding was found by milling into the yarn with a focus ion beam gun (FIB) and imaging with SEM. These different methods thus provided various microstructural details (structure, ribbon–ribbon boundary, folding and void fraction) of CNT multi-yarn which could be used to compare with other yarns fabricated with different procedures/sources as well to provide parameters for analytical tools. Further, these microstructural details can be related to macro mechanical and physical properties.