国产聚丙烯腈基炭纤维皮芯微区结构差异的拉曼光谱表征

Microstructure difference on skin and core of domestic PAN-based carbon fibers characterized by Raman spectroscopy

采用激光拉曼光谱对国产聚丙烯腈(PAN)基T300-12K炭纤维ST300和CCF300的横截面和表面开展微区检测,利用Voigt函数拟合分峰,研究炭纤维表面和芯部微结构的差异,并与日本东丽PAN基T300-12K炭纤维进行对比。结果表明:与东丽T300炭纤维相比,国产炭纤维微晶结晶度较低。国产炭纤维ST300存在明显的芯部和表面的结构差异,表面有序而芯部无序;CCF300和T300炭纤维从表皮区域到芯部,微晶尺寸相对均匀。国产炭纤维CCF300的单丝拉伸强度和东丽T300的接近,分别为3.31和3.35GPa;而ST300的拉伸强度和断裂伸长率偏低,说明PAN基炭纤维芯部沿径向的不均匀性对其单丝拉伸强度和断裂伸长率有不利影响;炭纤维表面有序度高于芯部的,造成拉伸强度偏低;在3种炭纤维中无定形碳含量越低,其弹性模量越高。

Laser Raman spectroscopy was used to characterize the microstructure difference between the cross sections and surfaces of domestic T300-12K PAN-based carbon fibers （ST300 and CCF300） with the spectra fitting by Voigt function, and the Japanese Toray PAN-based carbon fiber T300 was compared. The results show that the crystallization degree of domestic carbon fibers is lower than that of Toray T300. There is obvious skin-core structure difference in domestic carbon fiber ST300 with an ordered skin and disordered core. Compared with the crystallite size of ST300, the crystallite sizes of CCF300 and T300 are relatively uniform from skin region to core region. Domestic carbon fiber CCF300 as well as Toray T300 with nearly homogeneous structure have nearly equal tensile strengths, 3.31 and 3.35 GPa, respectively. Yet the tensile strength and strain rate of ST300 are lower, indicating that structure inhomogeneity in the transverse sections of PAN-carbon fibers have negative effect on the tensile strength. Carbon fiber with a more ordered surface than core region has lower tensile strength. Carbon fiber with lower content of amorphous carbon has higher elastic modulus.