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采用红外光谱、X射线能谱、激光显微共焦拉曼光谱、X射线衍射光谱和电子自旋共振等多种表征手段,定量探讨了热氧稳定化气氛中氧气浓度与聚丙烯腈纤维的径向结构转变以及与碳纤维结构和性能的关联.结果表明,随着氧气浓度的增大,氧气自皮层逐渐扩散到纤维内部,热氧稳定化纤维的径向结构趋于均质化.当热氧稳定化过程氧体积浓度(Vo)由20.38%增加到21.15%时,热氧稳定化纤维的皮芯结构逐渐减小,环化程度增幅显著,该过程对碳纤维皮部类石墨结构的形成具有促进作用,所得碳纤维的孔隙率减小,拉伸强度增大.当Vo大于21.34%时,热氧稳定化纤维的皮芯结构基本消失,但氧化程度过高且环化程度增幅缓慢,抑制了碳纤维皮部类石墨结构的形成,所得碳纤维的孔隙率增大,拉伸强度降低.控制Vo为21.15%～21.34%时,热氧稳定化纤维的环化和径向化学结构的均质化程度均得以提高,所得碳纤维在保持皮部较高石墨程度的同时促进了芯部类石墨结构的形成,此时拉伸强度最高,比在常规空气气氛条件下制备的碳纤维提高了12.22%.
The effects of oxygen concentration in the thermo-oxidative stabilization atmosphere and polyacrylonitrile fiber were quantitatively investigated by means of infrared spectroscopy, X-ray energy dispersive spectroscopy, laser micro-confocal Raman spectroscopy, X-ray diffraction and electron spin resonance Radial structure transformation and the relationship between structure and properties of carbon fiber.The results show that with the increase of oxygen concentration, oxygen gradually diffuse into the fiber from the cortex, and the radial structure of thermo-oxidized stabilized fiber tends to be homogenized. Oxygen stabilization process oxygen volume concentration (Vo) increased from 20.38% to 21.15%, thermal oxygen stabilized fiber core structure gradually decreases, the degree of cyclical significant increase in the formation of carbon fiber skin like graphite structure with The porosity of carbon fiber decreases, and the tensile strength increases.When the Vo is greater than 21.34%, the core-shell structure of the thermo-oxidized stabilized fiber disappears basically, but the oxidation degree is too high and the degree of cyclization increases slowly, which inhibits Carbon fiber skin part of the graphite structure, the resulting carbon fiber porosity increases, the tensile strength decreases.Wo the control of Vo 21.15% ~ 21.34%, thermal oxygen stabilized fibers cyclization and radial chemical structure of the degree of homogenization Have to Increase, resulting in carbon fibers while maintaining a high degree of graphite sheath portion of the core promotes the formation of a graphite structure category, the highest tensile strength at this time, increase the ratio of 12.22 percent carbon fibers prepared in an air atmosphere under conventional conditions.