Simultaneous reinforcement of the electrical and mechanical properties of carbon nanotube fibers by using a natural cross-linkable thermosetting polymer

A simple and efficient reinforcement strategy for the mechanical and electrical properties of carbon nanotube (CNT) fibers is developed by using natural urushiol as an eco-friendly cross-linking agent. This strategy is a sequential process including infiltration and cross-linking of urushiol onto CNT fibers. Based on this process, the tensile strength (430 ± 20 MPa), modulus (8.6 ± 1.0 GPa), toughness (12.7 ± 1.3 MJ m⁻³), and electrical conductivity (1616 ± 115 S cm⁻¹) of CNT fibers increase to 1.32 ± 0.01 GPa, 37.0 ± 2.1 GPa, 31.1 ± 2.6 MJ m⁻³, and 4053 ± 200 S cm⁻¹ with the photochemical cross-linking process and to 0.92 ± 0.09 GPa, 21.3 ± 3.9 GPa, 20.5 ± 2.3 MJ m⁻³, and 7430 ± 447 S cm⁻¹ with the thermal cross-linking process, respectively.