Stabilization of polyacrylonitrile fibers with carbon nanotubes

Stabilization is an energy-intensive and time-consuming step for making PAN-based carbon fiber. Here, a new pathway is shown that uses carbon nanotubes (CNT) to accelerate the reaction rate and to reduce the PAN stabilization time. Bi-component core-sheath PAN-PAN/CNT (10 wt% CNT) fibers and single-component PAN/CNT (10 wt% CNT) fibers were made. When comparing to PAN fiber with comparable diameter, the heat of stabilization (ΔH_reaction) of PAN/CNT fibers increased up to 3 times in the air, while it did not change in N₂. The addition of CNTs reduced the activation energy (E_a) of PAN cyclization by up to 12% but increased it for the oxidation reaction by up to 80% compared to PAN fibers. CNTs did not increase the kinetic constant of the cyclization reaction but increased it for the oxidation reaction (k_oxidation) by up to 5 times, when comparing to PAN fiber at 250°C. At the same temperature, the bi-component PAN/CNT fiber bundle was fully stabilized in less than 2 hours, while the PAN fibers with comparable diameter took 6 hours to stabilize. Porosity was observed in the PAN/CNT precursor as well as in the stabilized PAN/CNT. This porosity was considered, at least partially responsible for increased oxygen diffusion, and hence for the decrease in the PAN stabilization time.