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在惰性气氛条件下,将PAN预氧纤维在280~380℃进行热处理,通过固体核磁、元素分析、激光拉曼光谱、X射线光电子能谱及热重分析等方法研究了PAN预氧纤维在高温热处理过程中的结构演变及其对热稳定性的影响规律。结果表明:热处理过程中,PAN纤维内部发生了分子内环化、分子间环化、环结构及氧结构的重排等反应,随着热处理温度升高,环化程度加深,含氧结构减少;热稳定性研究表明,经过340℃处理的纤维结构规整度高,热稳定性较好。
Under inert atmosphere, the PAN pre-oxidized fibers were heat-treated at 280-380 ℃. The effects of thermal decomposition of PAN pre-oxidized fibers on the surface of PAN pre-oxidized fibers were investigated by solid state nuclear magnetic resonance, elemental analysis, Raman spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis. Structural Evolution during Heat Treatment and Its Effect on Thermal Stability. The results show that intraponylic cyclization, intermolecular cyclization, ring structure and rearrangement of oxygen structure occur in the PAN fiber during the heat treatment. As the temperature increases, the degree of cyclization increases and the oxygen structure decreases. Thermal stability studies show that the fiber structure treated at 340 ℃ has high regularity and good thermal stability.