Effects of KBrO3 on Chemical, Aggregation and Morphological Structure of Polyacrylonitrile (PAN) Precursor Fibers

Chen, Yatian; He, Bin; Chen, Qiufei; Malik, Hamza; Zhu, Hua; Wang, Yuhang; He, Jie; Ma, Bomou; Wang, Xueli; Zhang, Hui; Liu, Yong

doi:10.1007/s12221-023-00280-y

Cited by 4 publications

(3 citation statements)

References 42 publications

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“…Figure a shows the DSC curves of PAN fibers at each of the five stages (P1–P5) under a nitrogen atmosphere. A peak of heat release existed within the range of 250–300 °C, which was caused by the internal molecular chain of the fiber undergoing nitrile group cyclization to form a more heat-resistant trapezoidal structure during the heating process (Figure b) . During the steam stretching and heat setting stages, the onset temperature of the P5 exothermic peak was significantly delayed, and the peak narrowed owing to the increased activation energy of cyclization.…”

Section: Results and Discussionmentioning

confidence: 99%

“…A peak of heat release existed within the range of 250−300 °C, which was caused by the internal molecular chain of the fiber undergoing nitrile group cyclization to form a more heatresistant trapezoidal structure during the heating process (Figure 2b). 34 During the steam stretching and heat setting stages, the onset temperature of the P5 exothermic peak was significantly delayed, and the peak narrowed owing to the increased activation energy of cyclization. This change may be attributed to the more regular and ordered arrangement of PAN molecular chains and the more perfect crystal structure at the P5 stage, reflecting the criticality and importance of the steam drawing and heat setting stages in the processing and preparation of PAN fibers.…”

Section: Basic Structural Characterization Of Pan Fibersmentioning

confidence: 99%

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Microstructural Evolution during Dry-Jet Wet Spinning Postprocessing from Coagulation Bath Fiber to High-Performance Polyacrylonitrile Precursor Fiber

He,

Chen,

Zhu

et al. 2024

ACS Appl. Polym. Mater.

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High-quality polyacrylonitrile (PAN) precursor fibers positively affect the achievement of high-performance carbon fibers. To regulate the fiber structure and improve fiber quality, X-ray diffraction, scanning electron microscopy, small-angle X-ray scattering, high-resolution transmission electron microscopy, and atomic force microscopy, among other methods, were performed to investigate the internal microstructural evolution of PAN fibers during the postprocessing of dry-jet wet spinning and its correlation to high-performance acquisition. As the spinning process progressed, the lamellar structure perpendicular to the fiber axis in the as-spun coagulating bath fibers experienced disruption and recombination. At the same time, there was also the occurrence of the orientation arrangement of the PAN molecular chains and the directional extension and merging of microfibers. Eventually, the oriented microfibrils were tightly stacked to form crystalline layers, leading to continuous improvement in the fiber's crystalline structure and an increase in crystallinity and compactness. Moreover, the axial deviation of the internal pores within the fiber decreased continuously, accompanied by the axial elongation and fracture merging of the pores, which would enhance the regularity of axial alignment of microfibers and promote improvement in the fiber's tensile properties. Microfibril may further enhance the mechanical properties of the fiber by impeding the propagation of microcracks.

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Section: Results and Discussionmentioning

confidence: 99%

Section: Basic Structural Characterization Of Pan Fibersmentioning

confidence: 99%

Microstructural Evolution during Dry-Jet Wet Spinning Postprocessing from Coagulation Bath Fiber to High-Performance Polyacrylonitrile Precursor Fiber

He,

Chen,

Zhu

et al. 2024

ACS Appl. Polym. Mater.

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“…During this process, PAN filaments undergo cyclization, dehydrogenation, oxidation, and isomerization reactions. [11][12][13][14] And, the physical and chemical structure of the filaments undergoes many complex changes. Meanwhile, the PAN molecular chain gradually changes from a linear structure to a trapezoidal ring structure, a structure that allows the fibers to withstand higher temperature carbonization treatments.…”

Section: Introductionmentioning

confidence: 99%

Terpolymers of acrylonitrile, methyl acrylate, and 2‐acrylamido‐2‐methylpropane sulfonic acid for carbon fiber precursor: Effect of comonomers on the thermal stabilization of polyacrylonitrile copolymers

Chen,

He,

Chen

et al. 2023

J of Applied Polymer Sci

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Polyacrylonitrile (PAN) copolymers are important precursors for the preparation of high‐performance PAN‐based carbon fibers. In this study, different ratios of P(AN‐co‐AMPS) and P(AN‐co‐MA‐co‐AMPS) were prepared by solution polymerization. The compositional structure, thermal, and crystallization properties of P(AN‐co‐AMPS) and P(AN‐co‐MA‐co‐AMPS) were characterized. The results show that an increase in the AMPS feeding ratio is beneficial for improving the thermal stability and crystallization ability of the PAN copolymer; however, it also reduces the molecular weight of the copolymer and increases the cyclization exothermic peak temperature, which is not conducive to the preparation of high‐performance carbon fibers. This problem is avoided in P(AN‐co‐MA‐co‐AMPS), which maintains its high thermal stability and crystallization properties when appropriate amounts of MA and AMPS are introduced, and P(AN‐co‐MA‐co‐AMPS) has smoother cyclization exothermic rates, lower onset exothermic temperatures and lower peak exothermic temperatures. The structural changes of PAN, P(AN‐co‐MA), and P(AN‐co‐MA‐co‐AMPS) during thermal stabilization were investigated in detail using Fourier‐transform infrared spectroscopy and it was found that P(AN‐co‐MA‐co‐AMPS) formed more stable structures at lower temperatures. Furthermore, when the AN:MA:AMPS mass ratio is 97.5:1.5:1, P(AN‐co‐MA‐co‐AMPS) has the best overall performance. Our results suggest that the P(AN‐co‐MA‐co‐AMPS) has potential as a precursor for carbon fibers.

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Synthesis and thermal behavior of acrylonitrile/guanidine crotonate copolymer for carbon fiber precursor

Wang,

Malik,

et al. 2024

J of Applied Polymer Sci

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The thermal oxidation stabilization of polyacrylonitrile (PAN) copolymer is a highly exothermic process. It significantly impacts the quality of the finished PAN‐based carbon fiber, which is often addressed by adding appropriate comonomers. This paper synthesized guanidine crotonate (GCA) as a comonomer and copolymerized with acrylonitrile (AN) to prepare P(AN‐GCA). DSC analysis revealed that when compared to PAN and P(AN‐CA) copolymers, the initial exothermic temperature, maximum exothermic heat flux, and heat flux of P(AN‐GCA) copolymer were greatly reduced. FT‐IR spectroscopy showed that the degree of pre‐oxidation increased with the increasing comonomer GCA content, indicating that the addition of comonomer GCA could promote PAN pre‐oxidation cyclization and improve the copolymer's degree of pre‐oxidation. The activation energies of PAN and P(AN‐GCA) were 160 and 126 KJ/mol, respectively. It was shown that the addition of GCA could effectively reduce the activation energy of the cyclization reaction of the polymer while simultaneously promoting it. TGA analysis shows that the introduction of GCA improves the copolymer's thermal stability, and the yield at 800°C is more than 54%, which is at least 19% higher than PAN homopolymer. P(AN‐GCA) has the potential to be carbon fiber precursor.

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Effects of KBrO3 on Chemical, Aggregation and Morphological Structure of Polyacrylonitrile (PAN) Precursor Fibers

Cited by 4 publications

References 42 publications

Microstructural Evolution during Dry-Jet Wet Spinning Postprocessing from Coagulation Bath Fiber to High-Performance Polyacrylonitrile Precursor Fiber

Microstructural Evolution during Dry-Jet Wet Spinning Postprocessing from Coagulation Bath Fiber to High-Performance Polyacrylonitrile Precursor Fiber

Terpolymers of acrylonitrile, methyl acrylate, and 2‐acrylamido‐2‐methylpropane sulfonic acid for carbon fiber precursor: Effect of comonomers on the thermal stabilization of polyacrylonitrile copolymers

Synthesis and thermal behavior of acrylonitrile/guanidine crotonate copolymer for carbon fiber precursor

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