碳纤维的电化学表面改性及其表面结构演变

采用电化学氧化法对聚丙烯腈(PAN)基碳纤维进行表面改性，联用场发射扫描电子显微镜(FESEM)、拉曼光谱(Raman)和X射线光电子能谱(XPS)，表征了碳纤维表面物理化学结构。结合力学性能分析，评价了碳酸氢铵、氯化铵和硫酸铵三种电解质的改性效果，解释了碳纤维表面薄弱层产生的原因，分析了电化学改性碳纤维表面的机理。结果表明，在电化学改性过程中，碳纤维表面活性氧含量呈现梯形变化趋势，最高增幅达87.8%，而活性氮含量则不断增加直到饱和，可达到2倍增幅；相对于羧基等含氧基团，碳纤维复合材料(CFRP)层间剪切强度(ILSS)对胺基等含氮官能团更加敏感；当电解质中存在二价阴离子时，有利于减小碳纤维抗张强度的损失，甚至使其得到提高。

Electrochemical surface treatment and surface structure evolution of polyacrylonitrile-based carbon fibers

Polyacrylonitrile (PAN)-based carbon fibers (CFs) were continuously treated by an electrochemical oxidation method, and field emission scanning electron microscopy (FESEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to characterize the physical and chemical structure of the CF surface. The effects of NH₄HCO₃, NH₄Cl and (NH₄)₂SO₄ on the surface chemistry and physical structure of CFs were evaluated, and the presence of a weak surface layer and mechanisms of electrochemical surface treatment of CFs were also proposed. The results revealed that during the electrochemical treatment, the active oxygen content of the CF surface followed a trapezium trend with a maximum increase of 87.8%, and the active nitrogen content increased until saturation, at twice the initial value. The interlaminar shear strength (ILSS) of carbon fiber reinforced plastics (CFRP) was more sensitive to the presence of nitrogen functional groups than to carboxyl or other oxygen functional groups. The presence of a divalent anion in the electrolyte resulted in a reduction in the loss of tensile strength of CFs, and could even give rise to an improvement in tensile strength.