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

Tunçel, Kemal Şahin; Rahman, Md. Mahbubor; Demirel, Tuba; Karacan, İsmail

doi:10.1002/pen.25908

Cited by 7 publications

(2 citation statements)

References 74 publications

(105 reference statements)

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“…15,16 Currently, PAN-based precursors account for at least 90% of all carbon fiber production. 17,18 Additionally, the tow size, or the number of fibers in a single tow, is another vital factor influencing the cost. A fiber tow with a size less than 48,000 (48K) is considered a small tow, while a size greater than 48K is classified as a large tow.…”

Section: Introductionmentioning

confidence: 99%

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Hygrothermal resistance of large tow carbon fiber and its reinforced polymer composites

et al. 2023

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Large tow carbon fiber reinforced polymer (CFRP) has been used to reinforce structures serving in hygrothermal conditions, which can be greatly affected by hygrothermal conditions. In this study, the hygrothermal resistance of 48K and 12K carbon fibers and their CFRPs immersed in deionized water at 25, 40, and 60°C were analyzed and compared. The sizing agent on the carbon fiber surface was deboned or hydrolyzed after immersion, resulting in a reduction in the tensile strength, an increase in dispersion, and a decrease in surface activity for carbon fibers. The retention rate of tensile strength of 48K CFRP was higher than 89.7% but was less than that of 12K CFRP due to the higher dispersion of 48K fiber filaments. The interlaminar shear strength (ILSS) and Mode I interlaminar fracture toughness of 48K CFRP was greater than 12K CFRP due to the higher fiber surface activity of 48K carbon fibers and the stronger obstructing effect of 48K fiber tows on the diffusion of water. The degrees of post‐curing and hydrolysis of CFRP were less than 10%. The degradation of the fiber‐matrix interface and a decrease in the strength and elastic modulus of the matrix led to the degradation of the tensile properties, ILSS, and Mode I interlaminar fracture toughness of CFRP.Highlights Debonding of sizing agent reduced the strength of the carbon fiber filaments. Degrees of hydrolysis and post‐curing of the matrix caused by immersion were low. Retentions of ILSS and fracture toughness of 48K CFRP were higher than 12K CFRP. 48K fiber tow possessed a stronger obstructing effect on water diffusion.

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Section: Introductionmentioning

confidence: 99%

“…Among these, PAN is the most cost‐effective option and is best suited for manufacturing high‐performance fibers 15,16 . Currently, PAN‐based precursors account for at least 90% of all carbon fiber production 17,18 . Additionally, the tow size, or the number of fibers in a single tow, is another vital factor influencing the cost.…”

Section: Introductionmentioning

confidence: 99%

Hygrothermal resistance of large tow carbon fiber and its reinforced polymer composites

et al. 2023

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Multi‐step heating strategy during thermal stabilization of polyacrylonitrile multi‐filament bundle before carbonization

Hariri,

Tunçel,

Karacan

2024

Polymer International

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A polyacrylonitrile (PAN) multi‐filament bundle underwent a multi‐step heat treatment following impregnation with a solution of ammonium bromide, phosphoric acid and urea (A‐P‐U). The multi‐step thermal stabilization process was conducted in an air atmosphere at temperatures ranging from 200 to 245 °C for various stabilization times spanning from 10 to 70 min. Comprehensive analysis of physical and mechanical properties, infrared (IR) spectroscopy, X‐ray diffraction (XRD) and thermal analysis (DSC and TGA) revealed the significant influence of stabilization time on the structure and properties of thermally stabilized PAN multi‐filament bundle. The fiber thickness and linear density of the stabilized fibers decreased by approximately 29.5% and 10.6%, respectively, after 70 min of heat treatment. However, the fiber density value increased from 1.18 to 1.38 g cm−3 during the same stabilization time. Additionally, the carbon yield value obtained using TGA increased from 31% to 73% at 850 °C. The presence of A‐P‐U markedly reduced the time needed for the conversion of the PAN polymer into a cyclized structure through its nitrile groups, thereby accelerating the stabilization reactions. Furthermore, the IR spectra exhibited the appearance of CC bonds, signaling the creation of a crosslinked ladder‐like structure. The XRD traces confirmed the decrease in crystallinity with increasing stabilization time, consistent with the findings from IR spectra. The findings showed that the A‐P‐U integrated system is notably successful and proficient in promoting the cyclization of nitrile groups, thereby decreasing the time needed to establish a thermally stable structure capable of withstanding elevated carbonization temperatures. © 2024 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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Accelerated multistep thermal stabilization of polyacrylonitrile fibers using an ethylenediamine pretreatment

Tunçel,

Demirel,

Karacan

2024

J Mater Sci

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The polyacrylonitrile multifilament yarn underwent a multistep heat treatment process including stabilization times ranging from 5 to 75 min following impregnation with a 30% ethylenediamine (EDA) aqueous solution. A series of measurements were employed to determine the structure and properties of thermally stabilized PAN samples. These included fiber thickness, fiber density, flame testing, tensile testing, X-ray diffraction, thermal analysis (differential scanning calorimetry and thermogravimetric analysis), and infrared spectroscopy. The results from XRD and IR spectroscopy indicated that the rate of aromatization reactions increased with longer stabilization times. A detailed examination of the XRD curves obtained through curve-fitting procedures suggested a rapid transformation of the original structure into a disordered amorphous phase containing pre-graphitic domains, evidenced by a gradual reduction in the degree of apparent crystallinity of the original PAN sample. The integration of EDA before the thermal stabilization stage significantly reduced the cyclization time of nitrile groups in the PAN polymer structure, thereby accelerating the stabilization reactions. This chemical pretreatment also improved the thermal stability of the samples by promoting oxidative cross-linking of the PAN polymer chains. After a 75 min multistep stabilization, the carbon yield at 1000 °C was 70.5%. Conversion index values, calculated using IR, XRD, and DSC methods, were 98.3%, 94.8%, and 89.5% respectively for the 75 min sample. These findings highlight the importance of EDA in accelerating the formation of an aromatic structure, which is critical for withstanding the high temperatures of subsequent carbonization stages. Graphical abstract

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

Cited by 7 publications

References 74 publications

Hygrothermal resistance of large tow carbon fiber and its reinforced polymer composites

Hygrothermal resistance of large tow carbon fiber and its reinforced polymer composites

Multi‐step heating strategy during thermal stabilization of polyacrylonitrile multi‐filament bundle before carbonization

Accelerated multistep thermal stabilization of polyacrylonitrile fibers using an ethylenediamine pretreatment

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