Formation mechanisms and morphological effects on multi-properties of carbon nanotube fibers and their polyimide aerogel-coated composites

This paper aims to understand the formation mechanisms and morphological effects of polymer-aerogel reinforcements that guide the production of lightweight and multifunctional carbon nanotube (CNT) fibers. The CNT fibers and the polyimide aerogel-coated CNT fiber (PIA) composites were successfully developed. CNT thin films were fabricated from an aerogel technique; these films were then mechanically rolled to form CNT fibers of various diameters and densities. The CNT fibers thus prepared were dip-coated in the polyamic acid solutions to form gel-coated fibers, which were then dried with supercritical CO2 to obtain CNT/PIA composite fibers. The composite fibers presented as a core-shell structure in which the CNT fibers were tightly wrapped by porous polyimide aerogels. The relationships between the electrical and mechanical structural properties of the composites were investigated. By controlling the diameter of CNT fibers to 500 μm, we achieved electrical conductivity of 418 S/cm, and strength and stiffness values of 11.6 and 68.1 MPa, respectively.