Enhancement of Elasticity of PET Fiber via Grafting Helical Carbon Nanotubes

Elastic polyester fibers play an important role in daily textiles, but to raise the elasticity of regular polyethylene terephthalate (PET) fibers is still a challenge. Herein, inspired by springs, carboxylic helical carbon nanotubes (HCNTs‐COOH) are used as nanosprings to graft onto PET backbone to produce PET@HCNTs fibers (PETHf). Under single‐cycle loading tests, PETHf‐0.5 (containing 0.5% HCNTs‐COOH) achieves complete recovery at 5% elongation, with elastic recovery rate increased by 16.3% relative to neat PET fiber (PETf), and by 13.4% relative to the blend fiber of PET containing the same amount of HCNTs. After 10‐cycle loading tests with increasing elongation to 10%, the elastic recovery rate still reaches 62.6%, 21.3% higher than that of PETf, and 19.2% higher than that of the PET blend fiber. Furthermore, the fabric cylinder folding test indicates that PETHf‐0.5 has much better shape recovery than PETf. Application of PETHf in badminton strings shows a 16% increase in the bounce height of shuttlecock compared with nylon‐based commercial badminton strings, further confirming its excellent elasticity. Overall, this work provides a practical and effective strategy for enhancing the elasticity of regular PET fibers.