KMnO_4改性对聚丙烯腈原丝结构和性能的影响

The effect on structure and property of KMnO_4 modification on PAN fibers

用KMnO4对聚丙烯腈原丝进行化学改性处理,并通过傅立叶变换红外光谱仪、X射线衍射仪、示差扫描量热仪等测试手段研究了改性前后原丝的反应动力学,热性能,化学结构以及晶体结构的变化。结果表明,聚丙烯腈原丝经KMnO4改性处理后,环化反应所需的激活能降低,使原丝能在比较低的温度下开始环化反应,同时环化反应的放热量也有所增加;由于KMnO4的催化作用,使得改性处理后的PAN原丝形成了—CC—共轭结构;经KMnO4改性后原丝的晶体尺寸有所减小,这样有利于预氧化阶段氧的扩散,促进预氧化阶段的结构转变。

Polyacrylonitrile（PAN） fibers modified by potassium permanganate were characterized by FR-IR, DSC and X-ray diffractometer, in order to understand the reaction kinetics, thermodynamics, and the changes of chemical and crystal structure. The activation energy of cyclization reaction （E） reduces after the modification, and so does the temperature needed for the cyclization reaction. A new structure （ -C-C- conjugation） appears in the modified fibers, implying that KMnO4 is a catalyst to initiate the cyclization reaction. Also the modification gives rise to the decrease of crystal size in PAN fibers, which is helpful for the diffusion of oxygen during stabilization.