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.