Stretching-induced Alignment of Carbon Nanotubes and Associated Mechanical and Electrical Properties of Elastomeric Polyester-based Composite Fibers

Composite fibers composed of elastomeric segmented copolyetherester (CPEE) and poly(ethylene glycol)-functionalized multi-walled carbon nanotubes (MWCNT-PEG) (80/20 by wt%) were manufactured using wet-spinning and stretched up to 200 % at room temperature. It was confirmed that the introduction of PEG chains on the surfaces of the MWCNTs provides a specific interfacial interaction between the MWCNTs and CPEE matrix, which results in an enhanced alignment of the MWCNTs in the CPEE/MWCNT-PEG composite fibers through a simple stretching at room temperature without any high-temperature conditions required for the general drawing or stretching processes. As a result, the initial modulus and tensile strength of the composite fibers stretched up to 200 % were increased by 320 % and 350 %, respectively, as compared to the as-spun composite fibers. In addition, the electrical conductivity of the composite fibers was also noticeably increased with an increase in the stretching ratio. Interestingly, the correlation coefficient among the MWCNT alignment, modulus, and conductivity is 0.97, which means that the alignment of the MWCNTs is closely related to the change in the physical properties of the composite fibers.