Thermal behavior and kinetics during the stabilization of polyacrylonitrile precursor in inert gas

Xiao, Shuzhang; Lv, Honghong; Tong, Yuanjian; Xu, Lianyong; Chen, Biaohua

doi:10.1002/app.33656

Cited by 28 publications

(15 citation statements)

References 51 publications

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“…The cyclization of nitrile groups is highly exothermic and leads to the fragmentation of the chains owing to the heat building up rapidly in the sample [28]. The single exothermic peak observed in the DSC thermograms can be attributed to the cyclization of the PAN molecular chains [25]. It is well known that the cyclization reactions in PAN are based on the free radicals and initiated high temperature [29].…”

Section: Resultsmentioning

confidence: 99%

Thermal, Electrical and Surface Hydrophobic Properties of Electrospun Polyacrylonitrile Nanofibers for Structural Health Monitoring

et al. 2015

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This paper presents an idea of using carbonized electrospun Polyacrylonitrile (PAN) fibers as a sensor material in a structural health monitoring (SHM) system. The electrospun PAN fibers are lightweight, less costly and do not interfere with the functioning of infrastructure. This study deals with the fabrication of PAN-based nanofibers via electrospinning followed by stabilization and carbonization in order to remove all non-carbonaceous material and ensure pure carbon fibers as the resulting material. Electrochemical impedance spectroscopy was used to determine the ionic conductivity of PAN fibers. The X-ray diffraction study showed that the repeated peaks near 42° on the activated nanofiber film were α and β phases, respectively, with crystalline forms. Contact angle, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were also employed to examine the surface, thermal and chemical properties of the carbonized electrospun PAN fibers. The test results indicated that the carbonized PAN nanofibers have superior physical properties, which may be useful for structural health monitoring (SHM) applications in different industries.

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Section: Resultsmentioning

confidence: 99%

Thermal, Electrical and Surface Hydrophobic Properties of Electrospun Polyacrylonitrile Nanofibers for Structural Health Monitoring

et al. 2015

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“…The main reactions are cyclization, oxidation, and dehydrogenation. Since the 1950s, various types of reaction mechanism have been proposed to interpret the phenomena that occur throughout stabilization 1–14. In inert atmosphere, cyclization and the liberation of molecular gases takes place.…”

Section: Introductionmentioning

confidence: 99%

Mechanism and kinetics of oxidation during the thermal stabilization of polyacrylonitrile fibers

Xiao¹,

Cao²,

Wang³

et al. 2012

J of Applied Polymer Sci

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The thermal behavior and structural evolution during the thermal stabilization of polyacrylonitrile (PAN) fibers in N 2 and air were investigated using differential scanning calorimetry and solid-state 13 C nuclear magnetic resonance. It was found that an oxidation reaction, that generated carbonyl (C¼ ¼O) groups could occur at 160 C which has not been reported in the literature. It is proposed that the cyclized structures in the PAN macromolecule chains are a prerequisite for the oxidation. Further investigations indicate that with more cyclized structures in the PAN macromolecule chains, the oxidation proceeds more readily, which is consistent with the proposed mechanism. The kinetic parameters for the oxidation and cyclization reactions were estimated using the Kissinger method. The activation energies for the reactions of oxidation and cyclization for PAN fibers are about 96.4 kJ/mol and 190.0 kJ/mol, respectively, which implies that the cyclization is the rate determining step during the thermal stabilization of PAN fibers.

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“…On the other hand, it is well known that polyacrylonitriles (PANs) are widely used as precursors for fabricating high performance carbon fibers [8][9][10][11][12][13][14][15]. The formation of PAN precursor fibers possessing the heatresistance ability by heating to 200 ∼ 300°C is due to the change of the chemical structure from the linear molecular chain into ladder structures through a variety of chemical reactions including cyclization of nitrile groups leading to hydronaphthiridine rings, dehydrogenation leading to a certain degree of aromatization, and oxidation reaction leading mainly to acridone and some other structure [9,11,12].…”

Section: Introductionmentioning

confidence: 99%

Preparation and thermal stability of initiator fragments end-capped oligomers/silica nanocomposites

et al. 2016

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A variety of initiator fragments end-capped oligomers [X ∼ (M) n ∼ X; M = N, N-dimethylacrylamide (DMAA), acrylic acid (ACA), N-(1,1-dimethyl-3-oxobutyl)acrylamide (DOBAA), and acryloylmorpholine (ACMO); X = initiator fragments] were synthesized by oligomerization of the corresponding monomers catalyzed by the radical initiators such as ammonium persulfate ( A P S ) , 2 , 2 ′ -a z o b i s ( 2 -m e t h y l -N -( 2 -h y d r o x y e thyl)propionamide) (VA-086), and azobisisobutyronitrile (AIBN). These initiator fragments end-capped oligomers were found to cause a gelation toward not only water but also traditional organic media such as methanol, 2-propanol, propylene carbonate, 1,2-dichloroethane, and tetrahydrofuran. These obtained oligomers were applied to the nanocomposite reactions with silica nanoparticles in the presence of tetraethoxysilane (TEOS) under alkaline conditions to provide the corresponding oligomers/ silica nanocomposites. In these nanocomposites, X ∼ (M) n ∼ X/SiO 2 nanocomposites, which were prepared by using APS as an initiator, were found to afford the clear weight loss in proportion to the contents of the oligomers in the composites after calcination at 800°C. However, interestingly, X ∼ (M) n ∼ X/SiO 2 nanocomposites, which were prepared by using VA-086 and AIBN, afforded no weight loss corresponding to the contents of the oligomers in the composites even after calcination at 800°C.

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Thermal behavior and kinetics during the stabilization of polyacrylonitrile precursor in inert gas

Cited by 28 publications

References 51 publications

Thermal, Electrical and Surface Hydrophobic Properties of Electrospun Polyacrylonitrile Nanofibers for Structural Health Monitoring

Thermal, Electrical and Surface Hydrophobic Properties of Electrospun Polyacrylonitrile Nanofibers for Structural Health Monitoring

Mechanism and kinetics of oxidation during the thermal stabilization of polyacrylonitrile fibers

Preparation and thermal stability of initiator fragments end-capped oligomers/silica nanocomposites

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