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超临界二氧化碳(SCCO2)具有低黏度、高扩散性、高溶解度和高介电能力,利用超临界二氧化碳对PAN基碳纤维表面进行刻蚀。对超临界二氧化碳处理前后碳纤维进行分析,X射线光电子能谱(XPS)分析表明,随着处理温度的升高碳纤维表面O/C降低,这表明超临界二氧化碳对碳纤维有深度清洗的作用。X射线衍射(XRD)结果表明,随着处理温度的升高,碳纤维002晶系增加,并且石墨微晶厚度Lc和尺寸La增大。AFM观察表明,随着温度升高发现碳纤维表面沟槽变深并且碳纤维表面的粗糙度增加。此外,在200℃超临界二氧化碳处理过的碳纤维与环氧树脂的粘结性提高最高可达17.4%,经过超临界二氧化碳处理后碳纤维的层间剪切提高明显。
Supercritical carbon dioxide (SCCO2) has low viscosity, high diffusivity, high solubility and high dielectric capability. The surface of PAN-based carbon fiber is etched by using supercritical carbon dioxide. The analysis of the carbon fiber before and after the supercritical carbon dioxide treatment showed that the O / C of the carbon fiber decreased with the increase of the treatment temperature, which indicated that the supercritical carbon dioxide has a deep cleaning effect on the carbon fiber. X-ray diffraction (XRD) results show that as the treatment temperature increases, the 002 crystallinity of the carbon fiber increases, and the crystallite thickness Lc and size La of the graphite increase. AFM observation showed that as the temperature increases, the carbon fiber surface grooves become deeper and the surface roughness of carbon fibers increases. In addition, the supercritical carbon dioxide treated carbon fiber and epoxy resin at 200 ℃ increased the adhesion up to 17.4%, and the interlaminar shear of the carbon fiber increased obviously after supercritical carbon dioxide treatment.