PAN precursor was heated by isothermal treatment from 180 to 280℃ in inert atmosphere. Structure evolution and reaction process of stabilization of PAN fibers was studied by means of fourier transforming infrared spectroscopy and 13C solid nuclear magnetic resonance. The results indicate that cyclization and crosslinking reaction initiated by carboxy of comonomer occurred first. Dramatic cyclization and crosslinking reaction take place at about 220℃ . They became moderate while dehydrogenation go to be prominent as the temperature is higher than 240℃ .Residual change of enthalpy, liberation of H2 and residual content of H element are studied by differential scanning calorimetry , thermogravimetry-mass spectrometer and elemental analysis respectively. The reaction process proposed is verified again by these experiments. In addition, the initial stabilization process of PAN fibers became slower with the increase of tension.%在惰性气氛条件下,将PAN原丝在180-280℃进行恒温热处理.通过傅里叶变换红外、13C固体核磁共振方法研究了PAN纤维在热稳定化过程中的结构演变规律,并对PAN纤维的热稳定化反应进程进行了探索.结果表明:随着热处理温度升高,共聚单体中的羧基首先引发环化交联反应;在220℃左右开始发生剧烈的环化交联反应;当热处理温度高于240℃时,环化交联反应趋于平缓,脱氢反应逐渐占据主导地位.通过差式扫描量热仪、热重-质谱联立分析仪和元素分析仪分别研究了不同热稳定化阶段PAN纤维的剩余焓变量、H2的选出量及纤维中剩余H元素的含量.结果进一步佐证了提出的热稳定化反应进程.牵伸实验表明,张力越大,PAN纤维初期的热稳定化进程越缓慢.
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