【摘要】 采用Raman光谱、XRD、AE、XPS和TG-MS方法分析PAN预氧化纤维在连续炭化过程中纤维结构参数和C、N、O含量的变化,以及反应中小分子的释放情况。Raman光谱分析表明:在炭化过程中纤维内sp2杂化的C—C原子键距逐渐变大,晶体尺寸增大,石墨化度也随之提高,乱层石墨结构趋于完善;XRD分析结果表明:炭化过程中纤维的择优取向性提高,微孔含量减小是炭纤维体密度增大和强度逐步提高的原因所在;从预氧化纤维、低温炭化和高温炭化纤维的表面和本体元素分析的结果发现:炭化过程中碳元素的富集和非碳元素的脱除是由外向内的过程;TG-MS分析表明:小分子的释放主要发生在低温炭化的过程中,而高温炭化过程主要是大的梯形分子链交联脱除N2的反应。更多还原

【Abstract】 The microstructural evolution, elemental composition and gas releasing character of preoxided poly-acrylonitrile (PAN) fibers during continuous carbonization were investigated by Raman spectroscopy, XRD, XPS and TG-MS. Results indicate that the sp2 C—C bond length, crystal size and graphitization degree increase. The increase of orientation degree and the decrease of micropore volume are the fundamental reasons for the improvement of density and tensile strength of carbon fibers. Surface and global carbon contents of pre-oxidized PAN fibers, and both low temperature and high temperature carbonized fibers indicate that the loss of non-carbon atoms during carbonization propagates from the exterior to the interior of the fibers. TG-MS indicates that gases are released mainly at low temperature in carbonization. The cross-linking of trapezoid giant molecular chains to release nitrogen takes place at a high temperature during carbonization.更多还原