Structural transformation of polyacrylonitrile fibers during stabilization and low temperature carbonization

Hameed, Nishar; Sharp, Jordan; Nunna, Srinivas; Creighton, Claudia; Magniez, Kevin; Jyotishkumar, P.; Salim, Nisa V.; Fox, Bronwyn

doi:10.1016/j.polymdegradstab.2016.02.029

Cited by 117 publications

(84 citation statements)

References 15 publications

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“…This might cause some discrepancies between the simulations and experimental data, like the temperature when N2 molecules start to be produced. Even so, the experimental data for PAN precursor shows that nitrogen production is quite characteristic for temperatures > 800K 36 , whereas the observed crystallinity for PAN fibers is not reported above 600K 37 . These experimental observations reflect our simulations data, which shows the comparable nitrogen molecules productions for oxidized PAN are independent of initial polymer alignment.…”

Section: Figurementioning

confidence: 87%

Atomistic Scale Analysis of the Carbonization Process for C/H/O/N-Based Polymers with the ReaxFF Reactive Force Field

Kowalik¹,

et al. 2019

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During the carbonization process of raw polymer precursors, graphitic structures can evolve. The presence of these graphitic structures affects mechanical properties of the carbonized carbon fibers. To gain a better understanding of the chemistry behind the evolution of these structures, we performed atomistic scale simulations using the ReaxFF reactive force field. Three different polymers were considered as a precursor: idealized ladder PAN (polyacrylonitrile), a proposed oxidized PAN and PBO (poly(p-phenylene-2,6-benzobisoxazole)). We determined the underlying molecular details of polymers conversion into a carbon fiber structure. Since these are C/H/O/N-based polymers, we first developed an improved force field for C/H/O/N chemistry based on the Density Functional Theory (DFT) data with a particular focus on N2 formation kinetics and its interactions with polymer-associated radicals formed during the carbonization process. Then, using this improved force field, we performed atomistic scale simulations of the initial stage of the carbonization process for the considered polymers. Based on our simulation data we determined the molecular pathways for the formation of low-molecular weight gas-species, all-carbon rings crucial for further graphitic structures evolution and possible alignment of the evolved all-carbon 6-membered rings clusters.

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Section: Figurementioning

confidence: 87%

Atomistic Scale Analysis of the Carbonization Process for C/H/O/N-Based Polymers with the ReaxFF Reactive Force Field

Kowalik¹,

et al. 2019

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“…It can be seen that the linear density of PAN fiber gradually increases with doping solution concentration due to the adsorption of AlCl 3 , while the evolution of the linear density of the resultant CF shows an opposite tendency. Equation () was used to calculate the carbon yield, and the value decreases from 54.39% to 42.17% in the doping solution concentration range of 0–2.0 wt %, which means the doping process reduces the yield of PAN fibers at the same heat‐treatment conditions, and the main reason can be attributed to the less stabilized degree of the corresponding OF. However, this can be overcome by further optimizing the conditions.…”

Section: Resultsmentioning

confidence: 99%

Effects of doping aluminum chloride on stabilization and properties of polyacrylonitrile‐based carbon fibers

Chen

Lü

Jiang

et al. 2018

J of Applied Polymer Sci

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Polyacrylonitrile (PAN) gel fibers were immersed in 0–2.0 wt % aluminum chloride (AlCl3) aqueous solutions to fabricate Al‐doped PAN fibers and the resultant carbon fibers (CFs) on a continuous production line, and the effects of doping with AlCl3 on the stabilization and properties of PAN‐based CFs were investigated. The Al content in the PAN fibers and in the resultant CFs is 2800 and 5700 ppm, respectively, at 2.0 wt % doping solution concentration. Al compound particles were speculated to exist in the pores of PAN fibers, and they show strong inhibiting effects on both cyclization and oxidation reactions. However, the disadvantages can be overcome by a longer stabilization period or a higher stabilization temperature to produce CFs that have comparable mechanical properties with 2.98–3.20 GPa tensile strength and 210–220 GPa Young's modulus. Thermogravimetric analysis in air shows the weight of CFs increases remarkably from 19.0% to 59.3% at 850°C for Al content 0–1900 ppm, while it gradually decreases over 1900–5700 ppm.

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“…The first issue is what types of reactions really occur during the thermal stabilization. Generally, oxidation, dehydrogenation and cyclization are considered as the three major stabilization reactions [16,17,21,22]. But in fact, dehydrogenation is just a result of the oxidation reaction, since hydrogen is eliminated in the form of H 2 O by reacting with oxygen [21].…”

Section: A N U S C R I P Tmentioning

confidence: 99%

Simultaneous DSC/TG analysis on the thermal behavior of PAN polymers prepared by aqueous free-radical polymerization

Ouyang

Wang

et al. 2016

Polymer Degradation and Stability

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Structural transformation of polyacrylonitrile fibers during stabilization and low temperature carbonization

Cited by 117 publications

References 15 publications

Atomistic Scale Analysis of the Carbonization Process for C/H/O/N-Based Polymers with the ReaxFF Reactive Force Field

Atomistic Scale Analysis of the Carbonization Process for C/H/O/N-Based Polymers with the ReaxFF Reactive Force Field

Effects of doping aluminum chloride on stabilization and properties of polyacrylonitrile‐based carbon fibers

Simultaneous DSC/TG analysis on the thermal behavior of PAN polymers prepared by aqueous free-radical polymerization

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