氨水预处理时间对PAN原丝结构和性能的影响

Influence of the Time of Aqueous Ammonia-pretreatment on the Structure and Property of PAN Precursors

为了研究90℃下氨水预处理时间对聚丙烯腈(PAN)原丝结构和性能的影响,采用傅里叶转变红外光谱(FT-IR)、元素分析(EA)、纤维收缩率和差示扫描量热分析(DSC)对氨水预处理前后PAN原丝的结构转变和热性能变化进行表征分析。结果表明,氨水预处理引发了PAN原丝的环化反应,使得原丝颜色由最初的白色变为黄色,并且延长氨水预处理的时间可有效增加原丝中的—CN—CN—结构;此外,未经处理的原丝在热稳定化过程中的加热速率不能超过4℃/min,而氨水预处理则能提升原丝可承受的最大加热速率,当预处理时间达到30min时可使原丝能承受的最大加热速率提高到6℃/min。

In order to research the influence of the time of aqueous ammonia-pretreatment at 90 ℃ on the structure and property of polyacrylonitrile（PAN） precursors,Fourier transform infrared spectroscopy（FT-IR）,element analysis（EA）,ratio of fiber contraction and differential scanning calorimetry（DSC） are used to characterize the structural evolution and change in thermal performance of PAN precursors.These results indicate that aqueous ammonia-pretreatment has induced the cyclization reaction of PAN precursors which leads the color of precursors to change from white to yellow,and the quantity of structure of —CN—CN— can be risen up effectively by increasing the time of aqueous ammonia-pretreatment;in addition,the heating rate of untreated precursors in thermal stabilization can not exceed 4 ℃/min while aqueous ammonia-pretreatment can raise the maximum heating rate which could be used to oxidatively stabilize PAN precursors,especially the maximum heating rate will be raised to 6 ℃/min if the time of aqueous ammonia-pretreatment reaches up to 30 min.