Modification of accelerated thermal stabilization of polyacrylonitrile fibers by creating an oxygen concentration gradient in the production of carbon fiber

Objectives. The work set out to modify the technology of accelerated thermal stabilization of polyacrylonitrile (PAN) fibers used in the production of high-strength carbon fibers by reducing the formation of a heterophase core–shell structure to create an oxygen concentration gradient in heat treatment furnaces while maintaining a total thermal stabilization time of 30 min. The optimized process conditions led to milder thermal stabilization conditions, reducing both the final heat treatment temperature and the temperature difference between the thermal stabilization zones while simultaneously maintaining the target volume density parameter with respect to the previously developed accelerated thermal stabilization technology.

Methods. The thermal stabilization study of an industrially produced 12S precursor under different conditions on an experimental carbon fiber production line included measurement of bulk density, analysis of the thermal effects of the oxidation reaction by differential scanning calorimetry (DSC), and a study of micrographs of the resulting samples.

Results. The optimum process of thermal stabilization of PAN fiber was determined in four stabilization zones using selected compositions. The formation of the core–shell structure is significantly reduced when the target volume density and DSC thermal oxidation reaction effect of the stabilized polymer fiber are achieved in a given time (30 min).

Conclusions. The resulting technology regime is promising for the production of high strength (4.5 GPa, 4.9 GPa) PAN fibers at a reduced cost. While maintaining the total thermal stabilization time of PAN at the level of 30 min, which is three times less than the industrial processes used, it was possible to reduce the formation of a heterophase structure, as well as lowering the final processing temperature and reducing the temperature difference between the stabilization zones. This is promising in terms of a positive effect on the stability and safety of the industrial process, as well as ensuring the quality of the obtained products.

1. Trofimenko E.A., Bukharkina T.V., Verzhichinskaya S.V., Gavrilov Yu.V. Kinetic model of polyacrylonitrile fibers thermostabilization in nitrogen atmosphere. Izvestiya vysshikh uchebnykh zavedenii. Tekhnologiya tekstil’noi promyshlennosti = Proceedings of the Higher Educational Institutions. Textile Industry Technology. 2021;39(6):129–135 (in Russ.). https://doi.org/10.47367/0021-3497_2021_6_129

2. Trofimenko E.A., Bukharkina T.V., Verzhichinskaya S.V., Kozlovskii I.A. Accelerated stabilization of polyacrylonitrile fiber for the production high-strength carbon fibers. Izvestiyavysshikh uchebnykh zavedenii. Tekhnologiya tekstil’noi promyshlennosti = Proceedings of the Higher Educational Institutions. Textile Industry Technology. 2022;399(3):172–178 (in Russ.). URL: https://ttp.ivgpu.com/wp-content/uploads/2022/08/399_28.pdf. Accessed October 01, 2022.

3. Trofimenko E.A., Bukharkina T.V., Verzhichinskaya S.V., Staroverov D.V. Effect of carbonation duration during accelerated thermal stabilization of polyacrylonitrile fibers on the properties of carbon filaments. Khimicheskaya promyshlennost’ segodnya = Chemical Industry Developments. 2022;(2):16–19 (in Russ.). https://doi.org/10.53884/27132854_2022_2_16

4. Minus M.L., Kumar S. The processing, properties, and structure of carbon fibers. JOM. 2005;57(2):52–58. https://doi.org/10.1007/s11837-005-0217-8

5. Warner S.B, Peebles L.H., Uhlmann D.R. Oxidative stabilization of acrylic fibers. 1. Oxygen-uptake and generalmodel. J. Mater. Sci. 1979;14(3):556–564. https://doi.org/10.1007/BF00772714

6. Rahaman M.S.A., Ismail A.F., Mustafa A. A review of heat treatment on polyacrylonitrile fiber. Polym. Degrad. Stab. 2007;92(8):1421–1432. https://doi.org/10.1016/j.polymdegradstab.2007.03.023

7. Jie L., Yueyi Z., Lianfeng, Zhaokun M., Jieying L. Method for preparing high-strength carbon fiber: China Pat. CN102154740A. Publ. 13.05.2011.

8. Cook J.D., Taylor T., Deshpande G.V., Tang L., Meece B.D., Crawford S., Chiu S.C., Harmon B.D., Thomas A. Manufacture of intermediate modulus carbon fiber: Pat. WO2016144488A1. Publ. 15.09.2016.

9. Qin X., Lu Y., Xiao H., Song Y. Improving stabilization degree of stabilized fibers by pretreating polyacrylonitrile precursor fibers in nitrogen. Materials Letters. 2012;76:162–164. https://doi.org/10.1016/j.matlet.2012.02.103

10. Atkiss S.P., Maghe M.R. Precursor stabilisation process: Australia Pat. AU2022287549A1. Publ. 12.12.2022.

11. Keller A., Fauth G., Ziegler U. Method and device for stabilizing precursor fibers for the production of carbon fibers: Pat. US11486059B2 USA. Publ. 01.11.2020.

12. Lv M-y., Ge H-y., Chen J. Study on the chemical structure and skin-core structure of polyacrulonitrile-based fibers during stabilization. J. Polym. Res. 2009;16(5):513–517. https://doi.org/10.1007/s10965-008-9254-7