High-Modulus Low-Cost Carbon Fibers from Polyethylene Enabled by Boron Catalyzed Graphitization

5 years ago

High-Modulus Low-Cost Carbon Fibers from Polyethylene Enabled by Boron Catalyzed Graphitization

Nicholas Horstman, Steven Weigand, Denis Keane, James E. Rix, Chris Derstine, Eric J. Hukkanen, Bryan E. Barton, Mark Spalding, Weijun Wang, Michael J. Behr, Brian G. Landes, Jasson T. Patton

Currently, carbon fibers (CFs) from the solution spinning, air oxidation, and carbonization of polyacrylonitrile impose a lower price limit of ≈$10 per lb, limiting the growth in industrial and automotive markets. Polyethylene is a promising precursor to enable a high-volume industrial grade CF as it is low cost, melt spinnable and has high carbon content. However, sulfonated polyethylene (SPE)-derived CFs have thus far fallen short of the 200 GPa tensile modulus threshold for industrial applicability. Here, a graphitization process is presented catalyzed by the addition of boron that produces carbon fiber with >400 GPa tensile modulus at 2400 °C. Wide angle X-ray diffraction collected during carbonization reveals that the presence of boron reduces the onset of graphitization by nearly 400 °C, beginning around 1200 °C. The B-doped SPE-CFs herein attain 200 GPa tensile modulus and 2.4 GPa tensile strength at the practical carbonization temperature of 1800 °C. High-modulus carbon fibers from melt-spun polyethylene are produced in a continuous process via sulfonation and subsequent carbonization. The addition of boron as a graphitization catalyst greatly modifies the crystallographic microstructure and doubles the resulting tensile moduli, enabling low-cost industrial fibers with 240 GPa modulus after carbonization to 1800 °C and high-modulus fibers with 400 GPa after 2400 °C.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/smll.201701926