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通过使用XPS和XRD等表征手段研究了经低温碳化后PAN纤维中氮结合态的高温演变规律,推测了其反应机理,探讨了由氮结合态的演变所引起的纤维结构变化。结果表明:经低温碳化后PAN纤维中的氮主要以吡啶氮、叔胺氮和氨基/亚氨基3种结合态存在,当热处理温度在700℃以下时,纤维中吡啶氮含量最多;随着温度的升高,氨基/亚氨基和吡啶氮含量逐渐减少,而叔胺氮含量先呈增加趋势,温度升高到1000℃以后时,叔胺氮含量迅速下降;1300℃以后,纤维中的叔胺氮含量最多;PAN纤维中的氮以叔胺氮形式存在更有利于平面六元碳网的逐步完善。
The characterization of XPS and XRD were used to study the high temperature evolution of nitrogen-bound PAN fibers after low temperature carbonization. The reaction mechanism was presumed, and the changes of fiber structure caused by the evolution of nitrogen bound species were discussed. The results showed that nitrogen in PAN fibers mainly existed as pyridine nitrogen, tertiary amine nitrogen and amino / imino groups after carbonization at low temperature. When the heat treatment temperature was below 700 ℃, the content of pyridine nitrogen in fiber was the most. With the increase of temperature , The content of amino / imino and pyridine nitrogen decreased gradually, while the content of tertiary amine nitrogen increased firstly. When the temperature increased to 1000 ℃, the content of tertiary amine nitrogen decreased rapidly. After 1300 ℃, the content of tertiary amine Nitrogen content is the most; the nitrogen in PAN fiber exists in the form of tertiary amine nitrogen, which is more conducive to the gradual improvement of planar hexagonal carbon network.