PAN相对分子质量对静电纺丝制备纳米碳纤维显微结构的影响

Influence of relative molecular mass of PAN on microstructure of nano carbon fibers prepared by electrostatic spinning

以二甲基亚砜(DMSO)为溶剂,制备4组质量分数为12%的聚丙烯腈(PAN)聚合物溶液,PAN的相对分子质量分别为100000、150000、200000、250000。通过高压静电纺丝技术制备PAN纳米纤维,热处理进一步制备PAN基纳米碳纤维,热处理过程中预氧化和碳化温度分别为270℃和800℃。通过场发射扫描电子显微镜(FESEM)、拉曼光谱仪(RAMAN)对PAN纤维热处理前后表面形貌、分子振动等进行定性分析。结果表明,相对分子质量过低或者过高都会导致原丝产生严重的缠结现象且纤维直径不均匀,原丝中存在的缺陷会在热处理后遗留下来,且热处理过程中产生大量气体,纤维结构收缩,导致原丝中的缺陷进一步被放大,结合RAMAN分析可知150000相对分子质量PAN基纳米碳纤维性能最好。

Using dimethyl sulfoxide(DMSO)as solvent,four groups of polyacrylonitrile(PAN)polymer solutions with mass fraction of 12%were prepared,the relative molecular mass of PAN is 100000,150000,200000 and 250000,respectively.The PAN nanofibers were prepared by using the high pressure electrostatic spinning technique,and the PAN-based nano carbon fibers were further prepared by heat treatment,the preoxidation and carbonization temperatures during the heat treatment are 270℃and 800℃,respectively.The surface morphologies,molecular vibrations,etc.of the PAN fibers before and after heat treatment were qualitatively analyzed by using the field emission scanning electron microscope(FESEM)and Raman spectrometer(RAMAN).The results show that the too low or too high relative molecular mass will all lead to the original silk producing serious entanglement phenomenon and the diameter of the fibers being uneven.The defects existing in the original silk will be reserved after heat treatment,and a large amount of gases during heat treatment were produced,the shrinkage of the fiber structure leads to further enlarging the defects in the original silk.It is known by combining with Raman analysis that the performance of the PAN-based nano carbon fiber with relative molecular mass of 150000 is optimal.