Effects of oxygen content in the atmosphere on thermal oxidative stabilization of polyacrylonitrile fibers

Wang, Jing; Hu, Leiyang; Yang, Changling; Zhao, Weizhe; Lu, Youming

doi:10.1039/c6ra15308a

Cited by 35 publications

(23 citation statements)

References 35 publications

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“…Many researchers have discussed this issue using Fourier transform infrared spectroscopy (FTIR). [18,[23][24][25][26] In these studies, the evolution of chemical structure is mainly analyzed by the intensity of characteristic peaks. However, the appearance of overlapping peaks led to attribution of the peaks unable to determine.…”

Section: Introductionmentioning

confidence: 99%

The role of structural evolution of polyacrylonitrile fibers during thermal oxidative stabilization on mechanical properties

Yuan

Zhang

et al. 2020

J of Applied Polymer Sci

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The effects of chemical and physical structural evolution of polyacrylonitrile (PAN)-based carbon fibers precursor during thermal oxidative stabilization (TOS) on the mechanical properties of stabilized fibers were systematically studied. The results of Fourier transform infrared spectroscopy, wide-angle Xray diffraction, and density gradient column showed that the PAN fibers treated with high temperature and for long time have higher extent of cyclization, oxygen content, and crosslinking content. The crystallinity and crystallite size decreased with the increase of TOS time and temperature, whereas the bulk density of the stabilized fibers increased. The mechanical property results indicated that the decrease in tensile strength was inseparable from the formation of the cyclic structure and the amorphization transition of the crystal structure. The fibers have better structural stability when the extent of cyclization was 80-83%, the crystallinity was 34-45%, and the bulk density of stabilized fibers was 1.33-1.35 g/cm 3 , but exceeding these ranges, a serious skincore structure appeared.

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Section: Introductionmentioning

confidence: 99%

The role of structural evolution of polyacrylonitrile fibers during thermal oxidative stabilization on mechanical properties

Yuan

Zhang

et al. 2020

J of Applied Polymer Sci

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“…Figure 3shows the oxygen content and density of PAN and MFs. The chemical composition of PAN can be characterized by the Elemental Analyzer, and the oxygen content is a general parameter to evaluate the chemical changes of PAN fibers during thermal treatment[10,32,33]. The density of PAN fibers and MFs is another general reflection of the chemical and physical structural evolutions of PAN fibers.…”

mentioning

confidence: 99%

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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“…Abs (1360) and Abs (1454) are the absorbance of C-H and -CH 2groups, 20 respectively. 13 C solid state NMR spectra were measured on Bruker Avance 300 MHz instrument operating at 75.5 MHz by cross-polarization and magic angle spinning (CP/MAS), which equipped with 1 H-13 C double resonance 4 mm probe. The recycle delay and cross polarization time were set to 6 s and 4 ms, respectively.…”

Section: Characterizationsmentioning

confidence: 99%

“…12 However, because the oxidation reaction is a diffusion-controlled process, the stabilization time of these studies are generally long in order to gain adequate oxygen uptake. 13,14 It should be noted that based on isothermal DSC studies of PAN ber under air ow, the main exothermic reactions of PAN bers are executed in several minutes. [15][16][17][18] The rapid exothermic reaction of PAN bers reveal the potential of substantially shortening the stabilization time.…”

Section: Introductionmentioning

confidence: 99%

Effects of oxygen on the structural evolution of polyacrylonitrile fibers during rapid thermal treatment

et al. 2020

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Effects of oxygen content in the atmosphere on thermal oxidative stabilization of polyacrylonitrile fibers

Abstract: The effects of oxygen content in the atmosphere on thermal oxidative stabilization of polyacrylonitrile fibers have been studied based on the evolution of the interaction between cyclization and oxidation reactions.

Cited by 35 publications

References 35 publications

The role of structural evolution of polyacrylonitrile fibers during thermal oxidative stabilization on mechanical properties

The role of structural evolution of polyacrylonitrile fibers during thermal oxidative stabilization on mechanical properties

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

Effects of oxygen on the structural evolution of polyacrylonitrile fibers during rapid thermal treatment

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