Unveiling the Transformation of Liquid Crystalline Domains into Carbon Crystallites During Carbonization of Mesophase Pitch-Derived Fibers

41 Pages Posted: 21 May 2022

See all articles by Jiho Choi

Jiho Choi

Korea Institute of Science and Technology (KIST)

Yejung Lee

Korea Institute of Science and Technology (KIST)

Yangki Chae

Jeonbuk National University

Sung-Soo Kim

Korea Institute of Science and Technology (KIST)

Tae-Hwan Kim

Jeonbuk National University

Sungho Lee

Korea Institute of Science and Technology Information (KISTI) - Carbon Composite Materials Research Center

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Abstract

Despite extensive studies on structural changes during the carbonization process of pitch-derived fibers, an accurate description of the transformation from liquid crystalline domains into carbon crystallites is still limited to a few depictions based on common analytical tools for carbon fibers. We employed small-angle X-ray scattering (SAXS) with model fits for the unification of such disparate measures. The carbonization process below 1200 °C is divided into three sequential regimes: Regime I - disruption of stacked polyaromatic mesogens with fluctuations in elasticity from 300 to 600 °C; Regime II - full-scale transformation with enhancement in orientation from 600 to 800 °C; and Regime III - development of crystalline carbon structures with elongation of microvoids from 800 to 1200 °C. By examining the viscoelastic properties of pitch-derived fibers during heat treatment below 600 °C (Regime I), we found that the maximum softness of the pitch-derived fibers is achieved at 500 °C. This is due to the decrease in crosslink density between stacking structures, indicating that the crosslink density below 600 °C is a significant contributor to the formation of carbon crystallites.

Keywords: mesophase pitch, Carbon fiber, Microstructure, SAXS

Suggested Citation

Choi, Jiho and Lee, Yejung and Chae, Yangki and Kim, Sung-Soo and Kim, Tae-Hwan and Lee, Sungho, Unveiling the Transformation of Liquid Crystalline Domains into Carbon Crystallites During Carbonization of Mesophase Pitch-Derived Fibers. Available at SSRN: https://ssrn.com/abstract=4116207 or http://dx.doi.org/10.2139/ssrn.4116207

Jiho Choi

Korea Institute of Science and Technology (KIST) ( email )

14 gil 5 Hwarangno, Seongbuk-gu
Seoul, 02792
Korea, Republic of (South Korea)

Yejung Lee

Korea Institute of Science and Technology (KIST) ( email )

14 gil 5 Hwarangno, Seongbuk-gu
Seoul, 02792
Korea, Republic of (South Korea)

Yangki Chae

Jeonbuk National University ( email )

Korea, Republic of (South Korea)

Sung-Soo Kim

Korea Institute of Science and Technology (KIST) ( email )

14 gil 5 Hwarangno, Seongbuk-gu
Seoul, 02792
Korea, Republic of (South Korea)

Tae-Hwan Kim

Jeonbuk National University ( email )

Korea, Republic of (South Korea)

Sungho Lee (Contact Author)

Korea Institute of Science and Technology Information (KISTI) - Carbon Composite Materials Research Center ( email )

Jeonbuk
Korea, Republic of (South Korea)

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