The influence of stabilization efficiency on skin–core structure and properties of polyacrylonitrile fibers

Sun, Lihao; Shang, Lei; Xiao, Linghan; Zhang, Mengjie; Li, Ming

doi:10.1007/s10853-019-04257-2

Cited by 19 publications

(13 citation statements)

References 40 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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“…In order to further understand the effect of different pretreated cyclization degree on the carbon network structure of TOS fibers at atomic level, Raman spectroscopy as a powerful tool to obtain the change of carbon bond structure and order degree in skin‐core structure of TOS fibers 51,52 . Figure 7(a) showed the peak‐fitting curve of Raman spectra of SF5 fiber.…”

Section: Resultsmentioning

confidence: 99%

Effect of nitrogen pretreatment on the skin‐core structure of thermal oxidative stabilization polyacrylonitrile fibers

Deng

Zhang

2021

J of Applied Polymer Sci

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Polyacrylonitrile precursor was pretreated under nitrogen to study the effect of the extent of cyclization of pretreated fibers on the chemical structure, crystal structure and skin‐core structure of thermal oxidative stabilization (TOS) fibers. Based on the FTIR spectra, the cyclization degree of pretreated fibers was quantitatively calculated by a combination of peak‐fitting and second‐derivative operations. Combining the results of wide‐angle X‐ray diffraction, Raman spectroscopy and scanning electron microscope analysis, pretreatment was beneficial to increase the cyclized structure of TOS fibers, but inhibited the oxidation reactions in the TOS process. As the increase of cyclization degree of pretreated fibers, the oxygen content and crystal size of TOS fibers decreased and the crystal interplanar spacing increased; in the skin layer of TOS fibers, the ID/IGratio increased and brittle fracture area decreased. When the cyclization degree of pretreated fibers was in the range of 10%–35%, the skin‐core structure of TOS fibers was weakened, which demonstrated that proper pretreatment before TOS process can improve the skin‐core structure.

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“…Xue et al [15,16] reported that the pre-oxidation degree of PAN-based pre-oxidized fiber in the skin was higher, while it was the lowest in the core due to the decrease of oxygen content. The skin-core structure of pre-oxidized fibers could be weakened through the thermal treatment at a lower temperature for a long time, according to the work [17,18]. However, it was also easy to form the excessive oxygenated functional groups in the fiber.…”

Section: Introductionmentioning

confidence: 99%

Evolution and Regulation of Radial Structure of PAN Pre-Oxidized Fiber Based on the Fine Denier Model

Wang

et al. 2022

Materials

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Affected by ambient oxygen and thermal diffusion mechanism, the radial structural distribution of polyacrylonitrile (PAN) fiber during the pre-oxidation process will be inherited to the carbon fiber, which had a remarkable effect on the mechanical properties of carbon fiber. It is important to understand the evolution mechanism of radial structure evolution of PAN fiber during the pre-oxidation process to manufacture the high-performance carbon fiber. In this paper, a series of fine denier model fibers were prepared by adjusting the oxygen concentration to describe the structural characteristics at different radial regions of pre-oxidized fibers. The evolution mechanism of the radial structure of pre-oxidized fiber, with the increase of heat treatment temperature, was studied by the methods of optical microscope, C13 nuclear magnetic resonance (13C-NMR), and thermogravimetric analyzer (TGA). The results showed that along the radial direction of pre-oxidized fiber from skin to core layer, the degree of cyclization changed little while the dehydrogenation and oxygen-containing structure gradually decreased. Specifically, the oxygen-containing functional groups in the core decreased to the lowest level or even disappeared. A moderate increase of temperature in the initial and middle pre-oxidation processes could effectively promote the formation of cyclized structure and stabilize cross-linked ladder structure in the skin region of the fiber. With it, the thermal stability of obtained pre-oxidation fiber was improved.

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The influence of stabilization efficiency on skin–core structure and properties of polyacrylonitrile fibers

Cited by 19 publications

References 40 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

Effect of nitrogen pretreatment on the skin‐core structure of thermal oxidative stabilization polyacrylonitrile fibers

Evolution and Regulation of Radial Structure of PAN Pre-Oxidized Fiber Based on the Fine Denier Model

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