Enhanced carbon nanotube fiber and film by a high toughness epoxy

The extraordinary mechanical and physical properties of individual carbon nanotube (CNT) have motivated considerable interest in fabricating macroscopic structures. Among which, CNT fibers and CNT films are two types of promising candidates as composite reinforcement for real applications. Here we report the effect of introducing a high toughness epoxy resin on the tensile properties of CNT fiber and CNT film, which were both fabricated from vertically aligned CNT arrays. Fig.1 schematically presents the preparation procedure. The CNT fibers were spun by drawing and twisting, and modified by soaking them in the epoxy/acetone solution, while the CNT films were modified during the winding process by in-situ spraying the epoxy solution onto the rotating mandrel. As a result, comparing to the as-prepared CNT fiber, the tensile strength and modulus of epoxy modified CNT fiber were improved to 1.41GPa and 79.38 GPa, enhanced by 32.85% and 82.11%, respectively. The epoxy modified CNT film gave the strength and modulus up to 1.54 GPa and 58.58 GPa, 51.83% and 211.10% higher than the pure CNT film. This implicated that the direct spraying process in CNT film preparation is more efficient in modifying the CNT/epoxy interaction than the post treatment on the CNT fiber. The SEM, Raman, and infra-red spectrum analyses attribute the main mechanism of the improvement to the enhanced tube-tube interactions by the densification and higher degree of CNT orientation, as well as the interaction between the CNT and the epoxy molecules.