Optimization of the temperature program to scale up the stabilization of polyacrylonitrile fibers

The production of carbon fibers from polyacrylonitrile (PAN) includes a stabilization step before carbonization. Transferring this stabilization from the laboratory to a bigger scale cannot be performed without changes of the process parameters. Using a pure PAN polymer, fibers were spun and their stabilization as well as carbonization was studied in laboratory scale. The resulting materials were analyzed with FTIR, SEM and XRD. The stabilization step was then transferred to a pilot scale. Limitations given by the production line had to be taken into account to develop a suitable temperature treatment. The formation of a core/shell structure during stabilization was observed and was detrimental to the properties of the fiber after carbonization. Adjustments were made based on obtained results to balance the negative effects of high heating rates and strong temperature gradients. With the implemented changes the mechanical properties could be reproduced on the larger production scale.