To accurately understand how irradiation treatment influences the crystal structure variation of polyacrylonitrile (PAN) fibers during the pre-oxidation process, the crystal structure evolution of the irradiated PAN fibers after pre-oxidation was investigated by synchrotron wide-angle X-ray diffraction (WAXD) at beamline BL16B1 in transmission geometry, using a three-slit system at the Shanghai Synchrotron Radiation Facility. By employing highly sensitive 2D WAXD analysis, we observed the deformation of the orientation structure in the irradiated PAN fibers. It was found that irradiation treatment can reduce the quasicrystal structure formed in the early stage of the pre-oxidation process (200–220 °C). Irradiation further enhanced the decrease in crystal size, crystallinity, and preferred orientation during the pre-oxidation. The diffraction peaks for PAN fibers at q = 12 nm⁻¹ and 20.7 nm⁻¹ almost disappeared at 260 °C; meanwhile, a new peak appeared for the irradiated samples at q = 18.2 nm⁻¹, indicating the formation of a graphite structure, which confirmed by Raman spectra. The results showed that irradiation treatment can accelerate the pre-oxidation reaction of PAN fiber, reduce the time required for pre-oxidation, and improve the properties of carbon fiber by reducing the crystal size and crystallinity.

为了准确了解辐照处理如何影响预氧化过程中聚丙烯腈（PAN）纤维的晶体结构变化，通过同步加速器广角X射线衍射（WAXD）研究了预氧化后辐照的PAN纤维的晶体结构演变。 ）在传输几何中的光束线BL16B1处，使用上海同步辐射装置的三狭缝系统。通过使用高灵敏度的2D WAXD分析，我们观察到了辐照PAN纤维中取向结构的变形。研究发现，辐照处理可以减少在预氧化过程的早期阶段（200–220°C）形成的准晶体结构。辐照进一步增强了预氧化过程中晶体尺寸，结晶度和优选取向的降低。^-1和20.7 nm ^-1在260°C时几乎消失。同时，在q = 18.2 nm ^-1处，被辐照样品出现一个新峰，表明形成了石墨结构，这通过拉曼光谱得到了证实。结果表明，辐照处理可以加快PAN纤维的预氧化反应，减少预氧化所需的时间，并通过减小晶体尺寸和结晶度来改善碳纤维的性能。