Lyocell基炭纤维表面微结构的STM研究

Surface studies on Lyocell-based carbon fibers by scanning tunneling microscopy

采用SEM揭示出Lyocell基炭纤维(LCF)表面比粘胶基炭纤维(RCF)表面光滑,而后者粗糙的表面上还存在裂纹和沟槽,这也是导致RCF强度偏低的一个原因。尝试利用扫描隧道显微镜(STM)的原子级分辨率来研究LCF的表面微结构。在500nm×500nm观测范围内,发现了由25nm宽,150nm长的条状微结构组成的约150nm2大小的沿纤维轴呈近乎45°角排列的块状结构;并测得LCF表面碳原子间距离为0.331nm,结果表明Lyocell基炭纤维表面尚未形成完整的碳网六元环结构。

The surfaces of Lyocell-based carbon fiber (LCF) and rayon - based carbon fiber (RCF) were characterized by SEM and STM. SEM results show that the surface of LCF is much smoother while the surface of RCF is rougher with obvious cracks and grooves. This is responsible for the low tensile strength of RCF. By STM, it is found that, for a 500 rim x 500 rim area, the surfaces of LCF are characterized by a bulky structure with an area of about 150 nm(2), which, when further imaged at 50 nm x 50 rim, consists of smaller slug-like microstructures having a width of about 25 nm and length of 150 nm aligned at an angle of 45degrees to fiber axis. The distance between two adjacent carbon atoms of LCF is estimated to be 0.331 nm, which reveals that hexagonal carbon rings are not formed on the surface of LCF.