用在位X-射线衍射技术对PAN纤维的动态热解特征和环化动力学的研究

本文用在位X-射线衍射技术研究了PAN(聚丙烯腈)纤维的预氧化过程。由广角测得不同温度下试样随热解时间而变化的一系列的解析谱图中计算出样品的结晶度、微晶尺寸、晶面间距和芳构化指数,并对这些参数随实验条件变化的瞬间情况给予了解释。同时,还描述了PAN纤维在预氧化过程中的环化动力学行为。求解了各温度下的环化反应速率和活化参数。

INVESTIGATION ON THE CHARACTERISTICS OF THE DYNAMIC PYROLYSIS AND THE KINETICS OF THE CYCLIZATION FOR PAN FIBERS USING IN-SITU X-RAY DIFFRACTION TECHNIQUES

The preoxidizing process of polyacrylonitrile (PAN) fiber is investigated with in-situ X-ray diffraction techniques in this paper. Through experiment, we determined the curve of wide angles diffractering intensity. From the resolution charts which were gained of different times from the determination of PAN WAXD(wide-angle X-ray diffraction), one can calculate the crystallinity, the microcrystalline sizes, the spacing of lattice and the "aromatization index" values for the samples. And all this, these parameters with transient case of the change of the experimental condition were discussed in detail. Simultaneously, the behaviour of the cyclizatic kinetics during the processing of PAN fiber to preoxidized fiber was described. The rate constant of cyclization reaction and the activation parameter of cyclization at each temperature were calculated. The studies of these structural parameters and kinetics may provide some fundamental information for the optimizing control for the industrial process of the high-performance PAN-based carbon fibers.