Surface modification of carbon fiber is a traditional research field and many techniques have been developed to improve the adhesion force between fiber and the polymer matrix. However, most studies were focused on the carbon fibers with standard modulus. The surface of high-modulus carbon fiber (HMCF) is difficult to be activated due to the highly inert structure after graphitization. A convenient and effective surface modification method that can simultaneously improve the content of function groups with containing oxygen and nitrogen on the surface of HMCF was developed in this paper. The surface of HMCF was first anodized to be activated by electrochemical oxidation, and then the diethylenetriamine (DETA) was grafted by electrochemical grafting. The effect of the type of electrolyte on the electrochemical grafting of DETA was studied by the addition of NH₄HCO₃ and (NH₄)₂SO₄, respectively. The results indicated that the addition of NH₄HCO₃ electrolyte in DETA solution will promote the grafting and increase the grafted amount on HMCF surface. Moreover, the addition of (NH₄)₂SO₄ electrolyte can not only promote the grafting, but also oxidize the surface of the fibers further to generate more oxygen-containing groups. In addition, the interfacial performance of HMCF composites was significantly improved after modification by this method. Especially, when (NH₄)₂SO₄ was added to DETA solution, the inter-laminar shear strength (ILSS) of HMCF/epoxy composites reached 97.5 MPa, which was 257.1% higher than that of untreated HMCF.

碳纤维的表面改性是传统的研究领域，并且已经开发了许多技术来提高纤维与聚合物基体之间的粘合力。然而，大多数研究集中在具有标准模量的碳纤维上。由于石墨化后的高度惰性结构，高模量碳纤维（HMCF）的表面难以活化。本文研究了一种方便有效的表面改性方法，该方法可以同时提高HMCF表面含氧和氮的官能团的含量。首先对HMCF的表面进行阳极氧化，以通过电化学氧化将其活化，然后通过电化学接枝将二亚乙基三胺（DETA）接枝。_分别为4 HCO ₃和（NH ₄）₂ SO ₄。结果表明，在DETA溶液中添加NH ₄ HCO ₃电解质会促进接枝，并增加HMCF表面的接枝量。此外，添加（NH ₄）₂ SO ₄电解质不仅可以促进接枝，而且可以进一步氧化纤维表面以产生更多的含氧基团。此外，通过这种方法改性后，HMCF复合材料的界面性能得到了显着改善。特别是当（NH ₄）₂ SO ₄ 将其添加到DETA溶液中，HMCF /环氧树脂复合材料的层间剪切强度（ILSS）达到97.5 MPa，比未处理的HMCF高257.1％。