The effect of the ammonium persulfate and a multi-step annealing approach during thermal stabilization of polyacrylonitrile multifilament prior to carbonization

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

doi:10.1007/s10853-021-06209-1

Cited by 14 publications

(7 citation statements)

References 79 publications

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“…Then, by multiplying with the density values (g/cm 3 ), the original tensile properties of the yarns were converted into MPa or GPa. 61,62…”

Section: Methodsmentioning

confidence: 99%

“…Then, by multiplying with the density values (g/ cm 3 ), the original tensile properties of the yarns were converted into MPa or GPa. 61,62 For the electrical measurements, a DC four-point probe method was employed. The four-point probe characterization approach is a widely used standard method for analyzing the electrical properties of materials, especially in the semiconductor industry.…”

Section: Data Collectionmentioning

confidence: 99%

“…To improve conductivity and avoid electrostatic charge, the surfaces of the samples were coated with gold. 62 Experimental data analysis…”

Section: Data Collectionmentioning

confidence: 99%

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Fabrication of carbon fibers from the cupric ion impregnated and thermally stabilized poly(hexamethylene adipamide) precursor

Erzurumluoğlu

Rahman

Demirel

et al. 2021

Journal of Industrial Textiles

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The conversion of poly (hexamethylene adipamide) or polyamide 66 precursor fiber to carbon fibers was accomplished through thermal stabilization and carbonization processes. Thermal stabilization was conducted of cupric chloride (CuCl2)–ethanol-impregnated polyamide 66 (PA66) fibers in the air. To determine the influence of heating rate on the fiber structure and properties of the resultant carbon fibers, carbonization experiments were performed at selected temperatures of 500, 700, 900, and 1100°C using 2.5 and 5 °C/min heating rates with no dwelling. The results conclusively revealed that the volume density and tensile properties of the PA66 fiber were higher at 2.5 °C/min heating rate. After fixing the heating rate as 2.5°C/min, further carbonization experiments were conducted at temperatures from 500 to 1100°C, using increments of 100°C with no dwelling time. Linear density, volume density, fiber diameter, carbon yield, elemental composition, tensile, and electrical properties exhibited a strong dependence on the carbonization temperature. After taking into account the effects of structural defects (i.e., microvoids), tensile strength, and tensile modulus of the carbon fibers increased to 794 MPa and 92.4 GPa, respectively, when carbonized at 1100°C. X-ray diffraction analysis of the carbon fibers further revealed the existence of a greatly disordered (i.e., amorphous) structure, which developed during the carbonization process. FT-IR analysis confirmed the formation of highly aromatic carbon clusters at temperatures of 500°C and higher. The outcomes of electrical conductivity in this study confirm that the PA66 precursor was converted into a semi-conducting state once it was carbonized.

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“…Then, by multiplying with the density values (g/cm 3 ), the original tensile properties of the yarns were converted into MPa or GPa. 61,62…”

Section: Methodsmentioning

confidence: 99%

Section: Data Collectionmentioning

confidence: 99%

See 1 more Smart Citation

Fabrication of carbon fibers from the cupric ion impregnated and thermally stabilized poly(hexamethylene adipamide) precursor

Erzurumluoğlu

Rahman

Demirel

et al. 2021

Journal of Industrial Textiles

Self Cite

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“…where A c represents the area of the crystallization region and A a represents the area of the amorphous region. The grain size L c of the pre-oxidized fiber is generally calculated by the following formula [23]:…”

Section: Characterizationmentioning

confidence: 99%

Microstructure Evolution of Polyacrylonitrile-Based Fibers during Thermal Pre-Oxidation

Sun,

Wang,

Wang

et al. 2024

J. Compos. Sci.

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In this work, pre-oxidized polyacrylonitrile fibers are treated with ultrasonic etching and solution etching to produce ultra-thin sections. The evolution of the fibers’ microstructure in the pre-oxidation process is observed, and the transformation model of the microstructure of the pre-oxidized fibers is proposed. Scanning electron microscopy and high-resolution transmission electron microscopy were used to observe the microstructure changes of the fibers. Fourier transform infrared spectroscopy and X-ray diffraction were used to observe the chemical structure transformation and crystallization degree of the fibers in the pre-oxidation process. The results revealed that pre-oxidized fibers exhibited a smooth surface, while their interior consisted of fibrils. The longitudinal microfibrils were connected by the transverse microfibrils and amorphous regions. The fracture morphology of the fibers shifted from ductile to brittle, and the cross-section gradually became smoother. The linear molecular chain of PAN transformed into a ring structure as pre-oxidation progressed, subsequently leading to the cross-linking of this ring structure into an orderly trapezoidal configuration. The connection between the fibrils was enhanced, and the fiber structure became more compact and stable.

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“…The loss of tensile strength is expected in samples during thermal stabilization as in other similar studies. [24,74] Due to thermal degradation, the tensile strength of PAN samples impregnated with GC and then thermally stabilized is likely to decrease. However, the loss of tensile strength must not be too high.…”

Section: Mechanical Propertiesmentioning

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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The effect of the ammonium persulfate and a multi-step annealing approach during thermal stabilization of polyacrylonitrile multifilament prior to carbonization

Cited by 14 publications

References 79 publications

Fabrication of carbon fibers from the cupric ion impregnated and thermally stabilized poly(hexamethylene adipamide) precursor

Fabrication of carbon fibers from the cupric ion impregnated and thermally stabilized poly(hexamethylene adipamide) precursor

Microstructure Evolution of Polyacrylonitrile-Based Fibers during Thermal Pre-Oxidation

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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