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Carbon fiber (CF) obtained by pyrolysis of polyacrylonitrile (PAN-CF) surpasses metals in properties suitable for diverse applications such as the manufacture of aircraft and power turbine blades. PAN-CF obtained by pyrolysis at around 1200 °C shows a remarkably high tensile strength of 7 GPa, much higher than pitch-based CF (pb-CF) consisting of piles of pure graphene networks. However, little information has been available on the atomistic structure of PAN-CF and on how it forms during pyrolysis. We pyrolyzed an acrylonitrile 9-mer in a carbon nanotube, monitored the course of the reaction using atomic-resolution electron microscopy, and found that this oligomer forms a thermally reactive wavy graphene-like network (WGN) at around 1200 °C during slow graphitization taking place between 900 °C and 1800 °C. Ptychographic microscopic analysis indicated that such material consists of 5-, 6-, and larger-membered rings; hence is not flat but wavy. During PAN-CF manufacturing, many layers of WGN pile up to form a chemically and physically interdigitated noncrystalline phase that resists fracture and increases the tensile strength. pb-CF using nearly pure carbon starting material, on the other hand, forms a crystalline graphene network and is brittle.

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  This document is the Accepted Manuscript version of a Published Work that appeared in final form in Wavy Graphene-Like Network Forming during Pyrolysis of Polyacrylonitrile into Carbon Fiber, copyright ©  2023 American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/10.1021/jacs.3c02504

Keyword: carbon fiber, transmission electron microscopy, pyrolysis, in situ microscopy

Date published: 2023-06-07

Publisher: American Chemical Society (ACS)

Journal:

• Journal of the American Chemical Society (ISSN: 00027863) vol. 145 issue. 22 p. 12244-12254

Funding:

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.4246

First published URL: https://doi.org/10.1021/jacs.3c02504

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Updated at: 2024-05-30 08:30:08 +0900

Published on MDR: 2024-05-30 08:30:08 +0900