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Cui Y, Liu L, Song L, Li S, Wang Y, Shi Y, Wang Y. In Situ Study and Improvement of the Temperature Increase and Isothermal Retention Stages in the Polyacrylonitrile (PAN) Fiber Pre-Oxidation Process. Polymers (Basel) 2024; 16:547. [PMID: 38399927 PMCID: PMC10891822 DOI: 10.3390/polym16040547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 02/08/2024] [Accepted: 02/16/2024] [Indexed: 02/25/2024] Open
Abstract
The pre-oxidation process of Polyacrylonitrile (PAN) fibers is a complex procedure involving multiple stages of temperature increase and isothermal temperature retention. However, the impact of the temperature increase stage on PAN fiber has often been overlooked. To address this, samples were collected before and after the temperature increase and isothermal retention stages, treating them as separate influencing factors. Therefore, the pre-oxidation process can be divided into four distinct stages: (1) A temperature increase stage before the cyclization reactions: the PAN fiber's small-size crystals melt, and the crystal orientation changes under fixed tension, leading to shrinkage and increased orientation of the micropore. (2) An isothermal retention stage before the cyclization reactions: The crystal structure maintains well, resulting in minimal micropore evolution. The PAN fiber's crystal orientation and micropore orientation increased under fixed tension. (3) A temperature increase stage after the cyclization reactions: The PAN fiber's crystal melts again, reducing the average chord length and relative volume of the micropore. However, the PAN fiber can recrystallize under fixed tension. (4) An isothermal retention stage after the cyclization reactions: Significant crystal melting of the PAN fiber occurs, but the highly oriented crystals are maintained well. The average chord length and relative volume of the micropore increase. Recommendations for improving the pre-oxidation process are made according to these stages.
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Affiliation(s)
- Ye Cui
- Polymer High Functional Film Engineering Research Center of Liaoning Province, Shenyang University of Chemical Technology, Shenyang 110142, China (L.L.)
- School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China
| | - Lizhi Liu
- Polymer High Functional Film Engineering Research Center of Liaoning Province, Shenyang University of Chemical Technology, Shenyang 110142, China (L.L.)
- School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China
| | - Lixin Song
- Polymer High Functional Film Engineering Research Center of Liaoning Province, Shenyang University of Chemical Technology, Shenyang 110142, China (L.L.)
| | - Sanxi Li
- School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China
| | - Ying Wang
- Polymer High Functional Film Engineering Research Center of Liaoning Province, Shenyang University of Chemical Technology, Shenyang 110142, China (L.L.)
- School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China
| | - Ying Shi
- Polymer High Functional Film Engineering Research Center of Liaoning Province, Shenyang University of Chemical Technology, Shenyang 110142, China (L.L.)
- Research and Development, Dongguan HAILI Chemical Material Co., Ltd., Dongguan 523808, China
| | - Yuanxia Wang
- Polymer High Functional Film Engineering Research Center of Liaoning Province, Shenyang University of Chemical Technology, Shenyang 110142, China (L.L.)
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