Improved Mechanical and Electrical Properties of Carbon Nanotube Yarns by Wet Impregnation and Multi-ply Twisting

Abstract

Carbon nanotube (CNT) fibers, composed entirely of CNT bundles, have inferior mechanical properties as adjacent CNTs slide past each other when an external force is applied. Numerous surface coatings have been tried, but all these approaches have caused severe damage to the electrical properties of the resulting fibers. As a measure to address these problems, we present an effective method for the enhanced mechanical and electrical properties of CNT yarns by wet impregnation with a poly(vinylidene fluoride)/ionic liquid (PVDF/IL) composite and subsequent multiply twisting. Single twisting of three-ply yarns showed a superior electrical conductivity of up to 1500 S/cm, while braided twisting of pretwisted yarns exhibited excellent tensile performances, with a load capacity of 3.2 N, tensile strength of 12.7 g/de, and tensile strain of 35.2 %. The polarized Raman measurements confirmed the elevated CNT quality and high alignment of CNT bundles. The proposed approach of impregnated and twisted CNT yarns will lead to a variety of potential applications in sensors/actuators, e-textile devices, and fiber-shaped electrodes, which simultaneously requires ultra-light weight and good electrical and tensile properties.