【摘要】 采用扫描隧道显微镜(STM)对射频等离子法制备的聚丙烯腈(PAN)基预氧化纤维的表面超微结构进行了研究,定性了预氧化纤维的三级结构单元。结果显示:在微米尺度下,预氧化纤维表面分布有粗细不一、沿轴向排列的带状微纤,微纤之间相互交叉;在纳米尺度下,观察到微纤由相互缠结、紧密排列的超微纤组成,随着扫描范围的逐渐缩小,进一步看到超微纤由堆积起来的细小微晶组成;在原子级尺度上,微晶表面碳原子与高取向热解石墨(HOPG)相比不很规则,但具有取向排列趋势。更多还原

【Abstract】 The ultrastructure of PAN-based preoxidized fibers prepared by a radio frequency plasma was investigated by scanning tunneling microscopy,and micrometer-,nanometer-and atom scale surface structural(units) in the preoxidized fibers were qualitatively defined.At the micrometer scale,microfibrils with different diameters and in strip-like form are aligned parallel to the fiber axis,and these microfibrils intersect each other.At the nanometer scale,the microfibrils are seen to be composed of closely packed and intertwined smaller fibrils.By making the scanning area smaller,it can be seen that the smaller fibrils are formed by chains of primary microcrystallites on the atomic scale,the carbon atoms on the surface of the preoxidized PAN fibers tend to be(aligned) but this is irregular compared with highly oriented pyrolytic graphite.更多还原