The mechanism of thermal stabilization of polyacrylonitrile

Szepcsik, Balázs; Pukánszky, Béla

doi:10.1016/j.tca.2018.12.004

Cited by 30 publications

(26 citation statements)

References 26 publications

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“…Both ΔH in air and in nitrogen decreased with the increase of pretreatment temperature and time. This indicates that chemical reactions or structural changes during thermal pretreatment in nitrogen were beneficial to reactions in air (corresponding to stabilization) and nitrogen [28].…”

Section: Resultsmentioning

confidence: 96%

“…On the other hand, the uptrend of T i in nitrogen atmosphere implies that the thermal pretreatment in nitrogen had induced reactions or structural changes. As a result, the activation energy of PAN fibers was increased [27,28].…”

Section: Resultsmentioning

confidence: 98%

“…The downtrend of T i in air atmosphere with the increase of pretreatment temperature and time shows a lower initial temperature of pretreated fibers than that of PAN fibers. It means that the pretreated fibers need lower temperature to induce chemical and/or physical changes during thermal stabilization in air than the PAN fibers need, which implies that thermal pretreatment of PAN fibers in nitrogen may promote the reactions during thermal stabilization in air [8,9,[27][28][29][30][31]. On the other hand, the uptrend of T i in nitrogen atmosphere implies that the thermal pretreatment in nitrogen had induced reactions or structural changes.…”

Section: Resultsmentioning

confidence: 99%

“…The increasing of crystallinity and crystalline size (L c ) of PAN precursor fibers may benefit the mechanical properties of carbon fibers [41,42]. Figure 6 shows the TG-DTG of PAN fibers and MFs in air and nitrogen atmosphere, which can help to interpret the effects of thermal pretreatment in nitrogen on the stabilization and carbonization [27,28].…”

Section: Resultsmentioning

confidence: 99%

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Structural Transformation of Polyacrylonitrile (PAN) Fibers during Rapid Thermal Pretreatment in Nitrogen Atmosphere

et al. 2020

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The modification before the stabilization process could tune the exothermic behavior and the structural evolution of PAN fibers during stabilization. In this study, we demonstrate that a rapid thermal pretreatment in nitrogen can effectively mitigate the exothermic behavior of PAN fibers, such as decreasing the initial temperature, broadening the exothermal peak, and decreasing the nominal heat release during heating the fibers in air. The color of fibers has shown gradual changes from white to light yellow, yellow and brown during thermal pretreatment in nitrogen with the increase of pretreating temperature and time. The differential scanning calorimetry (DSC), Fourier Transform Infrared Spectrometer (FTIR), X-ray diffraction (XRD), and Thermogravimetric Analysis (TG) characterization have been applied to analyze the thermal properties, chemical and physical structural difference between PAN, and thermally pretreated PAN fibers. The thermal pretreatment of PAN fibers in nitrogen could induce cyclization, dehydrogenation, and cross-linking reactions, in which the cyclization play an important role on improving the cyclization index of stabilized PAN fibers. Meanwhile, the pretreatment can result in noticeable changes of the aggregation structure of PAN fibers, as indicated by the increase of crystallinity and crystalline size. These structural modifications can benefit the main cyclization reaction during stabilization and enhance the carbon yield in resultant carbon fibers. The rapid thermal pretreatment in nitrogen could increase efficiency of modification on PAN fibers, and that could save much time and energy. It is beneficial to manufacture low-cost carbon fibers and to spread the applications of carbon fibers.

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Structural Transformation of Polyacrylonitrile (PAN) Fibers during Rapid Thermal Pretreatment in Nitrogen Atmosphere

et al. 2020

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“…Thermal stabilization is a prerequisite process in PAN-based CFs production, during which linear PAN chain transfers into conjugated ladder structure mainly through cyclization and dehydrogenation for PAN to be thermal stable in subsequent carbonization process [16,17]. Hence, accelerating the formation of conjugated ladder structures is the key to accelerate thermal stabilization.…”

Section: Introductionmentioning

confidence: 99%

Accelerating the formation of the conjugated ladder structure of Poly(acrylonitrile-co-vinyl acetate) by cross-linked poplar lignin doped with boron phosphate

Shi

Ouyang

Wang

et al. 2020

Mater. Res. Express

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Utilizing renewable resources and accelerating thermal stabilization have been two main effective technical means to reduce the cost of poly(acrylonitrile) (PAN) based carbon fibre (CF). In this work, cross-linked poplar lignin (CPPL) with higher carbon content and 15 times the weight-average molecular weight of poplar lignin (PPL) was formed by doping boron phosphate (BP) in situ composites, which was blended with poly(acrylonitrile-co-vinyl acetate) (PANVA) to prepare a lowcost partially bio-based composite PANVA/CPPL-BP. During thermal stabilization, the C1s curvefitting of x-ray photoelectron spectroscopy (XPS) spectra showed that the conjugated ladder structure of PANVA/CPPL-BP started to form at 230°C, which was 20°C lower than PANVA. And the acceleration in forming conjugated ladder structures was further confirmed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric (TG), and TG-FTIR. During simulated low-temperature carbonization for composites stabilized at 230°C in advance, the addition of CPPL-BP greatly improved the order of graphitic structure for PANVA. The mechanical property of CF mats has also been obviously improved by CPPL-BP. The possible mechanism that CPPL-BP accelerating the formation of conjugated ladder structures for PANVA/ CPPL-BP during thermal stabilization was proposed. With such improvement on accelerating thermal stabilization and utilizing cheap bio-material at the same time, this PANVA/CPPL-BP composite has a great potential in developing low-cost CF.

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Fabrication of Porous Heteroatom‐Doped Carbon Networks via Polymer‐Assisted Rapid Thermal Annealing

Pagaduan,

Bhardwaj,

McCarty

et al. 2023

Adv Funct Materials

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Porous carbon materials have increasingly drawn interest for applications ranging from supercapacitive energy storage to bioengineering. However, a simple and scalable fabrication process of such materials, employing low‐cost chemical compounds without sacrificing morphological and chemical control, remains lacking. Here, a novel, rapid, continuous bottom‐up strategy for synthesizing structurally tunable porous carbon network films on insulating and conductive substrates is reported. By employing rapid thermal annealing (RTA) of a commercial polyacrylonitrile‐based blend, simultaneous phase separation and thermal crosslinking are induced, effectively freezing the structure. Subsequent burning of degradable components generates a porous carbon framework ( ≈ 360 to 700 nm) doped with nitrogen and oxygen atoms. Introducing a boron‐containing reagent in the precursor solution enables boron doping and pore size reduction as small as 20 nm, enhancing materials' performance. The direct fabrication of micro‐supercapacitors on stainless steel substrates is demonstrated, achieving an areal capacitance of 12.7 mF cm−2 at 50 mV s−1, with ≈98% retention after 10 000 charge/discharge cycles. The benefit of boron doping is further highlighted for wound healing applications. Because RTA is already an established industrial method, this platform directly facilitates the synthesis of functional porous heteroatom‐doped carbon structures using commercial polymers and dopants for various applications.

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The mechanism of thermal stabilization of polyacrylonitrile

Cited by 30 publications

References 26 publications

Structural Transformation of Polyacrylonitrile (PAN) Fibers during Rapid Thermal Pretreatment in Nitrogen Atmosphere

Structural Transformation of Polyacrylonitrile (PAN) Fibers during Rapid Thermal Pretreatment in Nitrogen Atmosphere

Accelerating the formation of the conjugated ladder structure of Poly(acrylonitrile-co-vinyl acetate) by cross-linked poplar lignin doped with boron phosphate

Fabrication of Porous Heteroatom‐Doped Carbon Networks via Polymer‐Assisted Rapid Thermal Annealing

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