A method of using modified epoxy resin (PEG-E51) and graphene oxide (GO) as sizing agent in different pH has been proposed and applied to improve the interfacial interactions and bonding of carbon fiber (CF) reinforced epoxy resin-based (EP) composites. The PEG-E51 and GO complex sizing in different pH is prepared and then coated on CF surfaces homogeneously. The sizing layer forms on the fiber surfaces, and multiple GO sheets are introduced successfully surrounding the CFs. The surface morphologies of CFs change distinctly with different pH. The interfacial shear strength increases from 51.36 MPa for bare fiber-reinforced EP composites to 66.62 MPa for composites reinforced by CFs coated with GO only. However, a significant improvement is achieved when the pH is adjusted to 10, making the interfacial shear strength grow up to 77.23 MPa. Furthermore, scanning electron microscopy results and interlaminar shear strength test are in agreement with each other, suggesting better interface bonding of composites by regulating pH of PEG-E51 and GO complex sizing. Besides, the interfacial interaction mechanism in CF reinforced composites is also explored, that is, the positive effects of roughness and specific surface area in complex interfacial layers lead to the improvement of interfacial properties.

中文翻译：

---

通过调节界面处的 PEG-E51 和氧化石墨烯复合物的大小来增强碳纤维/环氧树脂复合材料的界面相互作用

提出了一种在不同pH值下使用改性环氧树脂（PEG-E51）和氧化石墨烯（GO）作为施胶剂的方法，并应用于改善碳纤维（CF）增强环氧树脂基（EP）的界面相互作用和粘合复合材料。制备不同 pH 值的 PEG-E51 和 GO 复合物，然后均匀地涂覆在 CF 表面。在纤维表面形成上浆层，并且在 CF 周围成功引入了多个 GO 片。CFs 的表面形貌随 pH 的不同而发生明显变化。界面剪切强度从裸纤维增强 EP 复合材料的 51.36 MPa 增加到仅由 GO 涂层的 CF 增强的复合材料的 66.62 MPa。然而，当 pH 值调整到 10 时，实现了显着的改善，使界面剪切强度增长到 77.23 MPa。此外，扫描电子显微镜结果和层间剪切强度测试结果相互一致，表明通过调节 PEG-E51 和 GO 复合物的 pH 值可以更好地实现复合材料的界面结合。此外，还探讨了CF增强复合材料中的界面相互作用机制，即复杂界面层中粗糙度和比表面积的积极影响导致界面性能的改善。