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Materials (Basel). 2018 Jun 15;11(6). pii: E1017. doi: 10.3390/ma11061017.

Properties and Structure of In Situ Transformed PAN-Based Carbon Fibers.

Author information

1
College of Mechanical and Equipment Engineering, Hebei University of Engineering, Handan 056038, China. caojingjing@hebeu.edu.cn.
2
College of Mechanical and Equipment Engineering, Hebei University of Engineering, Handan 056038, China. zhaowenwu1105@163.com.
3
College of Mechanical and Equipment Engineering, Hebei University of Engineering, Handan 056038, China. gaoshuzhen@163.com.

Abstract

Carbon fibers in situ prepared during the hot-pressed sintering in a vacuum is termed in situ transformed polyacrylonitrile-based (PAN-based) carbon fibers, and the fibrous precursors are the pre-oxidized PAN fibers. The properties and structure of in situ transformed PAN-based carbon fibers are investigated by Nano indenter, SEM, TEM, XRD, and Raman. The results showed that the microstructure of the fiber surface layer was compact, while the core was loose, with evenly-appearing microvoids. The elastic modulus and nanohardness of the fiber surface layer (303.87 GPa and 14.82 GPa) were much higher than that of the core (16.57 GPa and 1.54 GPa), and its interlayer spacing d002 and crystallinity were about 0.347 nm and 0.97 respectively. It was found that the preferred orientation of the surface carbon layers with ordered carbon atomic arrangement tended to be parallel to the fiber axis, whereas the fiber core in the amorphous region exhibited a random texture and the carbon atomic arrangement was in a disordered state. It indicates that the in situ transformed PAN-based carbon fibers possess significantly turbostratic structure and anisotropy.

KEYWORDS:

carbon atomic arrangement; carbon layer; in situ transformed PAN-based carbon fibers; turbostratic structure

Conflict of interest statement

The authors declare no conflicts of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.

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