Multi-walled carbon nanotube composite fiber formation in a water coagulation bath and application as wire heater

Abstract

A type of high-yield multi-walled carbon nanotubes (MWNTs) with a diameter of 4–13 nm was prepared by cracking propylene over Co-Mo/Al2O3-MgO catalyst. The pristine MWNTs were well dispersed in N-Methyl-Pyrrolidone (NMP) solution of an oil soluble non-ion surfactant. Then the MWNT dispersion was extruded out of a spinneret into a rotating water coagulation bath to form a free-standing gel fiber with ribbon shape. The surfactant was insoluble in water while NMP was miscible with water, which promoted the formation of gel fiber. When the gel fiber was dried, a solid MWNT-surfactant composite fiber was obtained. The composite fiber had certain flexibility. However, the tensile strength was only 15.6 ± 1.3 MPa, which was mainly limited by the weak orientation of MWNTs along the fiber and the lack of compactness of MWNTs inside the fiber. In addition, the electrothermal properties of the 3 cm MWNT-surfactant composite fiber as wire heater were also evaluated. The composite fiber possessed rapid temperature response under different voltages. The steady-state temperature reached 48.1 °C, 74.0 °C and 100.2 °C, respectively, at 10 V, 15 V and 17.5 V.