Super-strong CNT composite yarn with tight CNT packing via a compress-stretch process.

Carbon nanotube yarn (CNTY) with a large size and excellent mechanical properties could have wide technological influence in fields ranging from electrical devices to wearable textiles; however, inventing such CNTY has remained excessively challenging. Herein, we introduce an interesting approach to produce highly densified, robust CNT/polyvinyl alcohol composite yarn (CNT/PVA-P CY) with a large diameter and excellent comprehensive properties via a compressing and stretching method. Our method allows the PVA polymer chains to be well-dispersed into CNT intra- and inner-bundles with a controllable diameter and desirable mechanical properties. The resulting CNT/PVA-P CY exhibits an ultra-large diameter (∼140 μm), admirable mechanical properties (tensile strength of up to 1475 MPa and Young's modulus of up to 24.98 GPa), light weight (1.28 g cm-3), high electrical conductivity (792 S cm-1), outstanding flexibility, and anti-abrasive abilities. The successful obtainment of such attractive properties in yarns may provide new insights for the construction and exploitation of CNTY as a potential candidate to replace traditional carbon fibers for various applications.