A novel methodology for designing thermal processes in order to optimize stabilization of polyacrylonitrile (PAN) fibers

Soulis, Spyridon; Dragatogiannis, Dimitrios A.; Charitidis, Costas A.

doi:10.1002/pat.4870

Cited by 10 publications

(7 citation statements)

References 50 publications

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“…During the stabilization process, the characteristics of the fiber bundles significantly affect their heat transfer and exothermic properties. − Figure shows the temperature variation of different filament bundles. The heat transfer and exothermic properties of large and small tows showed obvious differences with 48 K fibers as the boundary.…”

Section: Resultsmentioning

confidence: 99%

Exothermic Behavior and Structural Transformation of Large-Tow Polyacrylonitrile Fibers during Thermo-Oxidative Stabilization

Yang

Chen²,

Liu

et al. 2023

Ind. Eng. Chem. Res.

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Large-tow carbon fibers have great potential in industrial and civil fields due to their high production capacity and processing efficiency. However, the dense packing of large-tow filaments exacerbates the heat accumulation within the bundle during the exothermic stabilization reaction, which significantly adds to the difficulty of process control and reduces product performance stability. These thermal behaviors are strongly affected by the configuration of the filament bundle, such as the tow size and the tow spreading width. Therefore, having a clear understanding of the effect of tow configuration on the stabilization process is crucial for producing large-tow carbon fiber with desired qualities. In this study, the effect of tow size and tow spread width on the thermal behavior and the structural transformation of polyacrylonitrile (PAN) fibers during stabilization was quantitatively investigated through dynamic monitoring of the temperature in the center of the bundle. The results indicated that the center temperature of large-tow bundles rises much slower due to the poor heat conductivity of PAN polymer fibers. When the exothermic reaction is initiated in the center of the bundle, the center temperature quickly rises as a result of poor heat dissipation within the densely packed large-tow fibers. The surface-center temperature differences result in significant structural heterogeneities within the bundle, as evidenced by the Fourier transform infrared spectroscopy, dynamic scanning calorimetry, and single-filament tensile tests. These phenomena are produced for a bundle size higher than 48 K. Finally, a processing model covering the tow size, the spread width, and the maximum differences in temperature between the bundle center and environments is proposed for product quality assurance.

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Section: Resultsmentioning

confidence: 99%

Exothermic Behavior and Structural Transformation of Large-Tow Polyacrylonitrile Fibers during Thermo-Oxidative Stabilization

Yang

Chen²,

Liu

et al. 2023

Ind. Eng. Chem. Res.

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“…[9][10][11] DOI: 10.1002/macp. 202300114 Various pretreatment methods are used on PAN fibers to manufacture low-cost carbon fibers and improve their mechanical properties, such as annealing before the pre-oxidation process, [12,13] hydroxylamine hydrochloride treatment, [1] heating in a nitrogen atmosphere, [14] or microwave treatment. [15] These modifications benefit the cyclization reaction during the pre-oxidation process, saving time and energy and enhancing the carbon yield.…”

Section: Introductionmentioning

confidence: 99%

Research on Improving the Pre‐Oxidation Process of the Excellent Mechanical Strength Carbon Fiber

Cui,

Liu,

Song

et al. 2023

Macro Chemistry & Physics

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This study used Synchrotron Wide‐Angle X‐ray Diffraction (WAXD) and Synchrotron Small Angle X‐ray Scattering (SAXS) to carry out in‐situ study of the pre‐oxidation process of Polyacrylonitrile (PAN) fibers with two different preparation processes. Through analysis of 2D WAXD/SAXS data, This study divides the evolution of PAN fiber's crystal and microporous structures during pre‐oxidation into three and two stages, respectively. The evolution of PAN fiber's crystal structure during pre‐oxidation can be divided into three stages: 1) Initial stage: small‐sized crystals melt, crystal orientation decreases, and no cyclization reactions occur. 2) Intermediate stage: cyclization reactions happen in the amorphous region, leading to increased crystal size, crystal orientation, and crystallinity. 3) Final stage: cyclization reactions occur in the crystal region, resulting in reduced crystal size and orientation. The evolution of microporous structure can be divided into two stages: microporous shrinkage stage and microporous expansion stage. These features were analyzed using 2D WAXD/SAXS techniques. This study provides valuable references and guidance for the industrial production of PAN fibers by exploring the mechanism of the pre‐oxidation process in‐depth.This article is protected by copyright. All rights reserved

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“…[ 37 ] In the carbonization stage, the elements other than carbon are removed from the structure, and the carbon content increases as a result of the gradual heating of the thermally stabilized fiber in an inert environment. Although the carbonization temperature is usually between 1000°C and 2500°C, [ 38 ] it varies according to the mechanical properties obtained from the final carbon fiber. To achieve high tensile strength, a carbonization temperature of up to 1500°C is preferred to employ.…”

Section: Introductionmentioning

confidence: 99%

The impact of guanidine carbonate incorporation on the molecular structure of polyacrylonitrile precursor fiber stabilized by a multistep heat treatment strategy

Tunçel

Rahman

Demirel

et al. 2022

Polymer Engineering & Sci

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Thermal‐oxidative stabilization of the polyacrylonitrile (PAN) precursor was performed employing a multi‐step heat treatment strategy in an air circulating furnace. In this approach, the applied temperature was gradually increased from 200°C to 250°C employing several stages for different stabilization durations. Fifteen percent guanidine carbonate (GC) was found as optimum to incorporate with the PAN precursor fibers to accelerate the thermal‐oxidative stabilization process. Characterization techniques, including X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), tensile strength, volume density, linear density, fiber thickness, and burning test have been performed to monitor the changes in PAN structure. Test results of the stabilized samples were compared with the reference sample results to demonstrate the accelerating effect of GC integration. Findings showed that GC pretreatment enhanced and accelerated the cyclization of nitrile groups in the PAN polymer structure and allowed the quicker formation of a thermally stable structure. The analysis of the experimental results revealed that GC integration and employing the multi‐step heat treatment strategy helps greatly to cut the overall PAN‐based carbon fiber production cost.

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A novel methodology for designing thermal processes in order to optimize stabilization of polyacrylonitrile (PAN) fibers

Cited by 10 publications

References 50 publications

Exothermic Behavior and Structural Transformation of Large-Tow Polyacrylonitrile Fibers during Thermo-Oxidative Stabilization

Exothermic Behavior and Structural Transformation of Large-Tow Polyacrylonitrile Fibers during Thermo-Oxidative Stabilization

Research on Improving the Pre‐Oxidation Process of the Excellent Mechanical Strength Carbon Fiber

The impact of guanidine carbonate incorporation on the molecular structure of polyacrylonitrile precursor fiber stabilized by a multistep heat treatment strategy

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