Designing the interface in polymer composites is fundamentally a challenging task. Here, we demonstrate a strategy to engineer the interphase microstructure in carbon fiber/epoxy composites (CFRPs) using carbon nanotubes (CNTs). The incorporation of CNT modifies the interfacial mechanics and interfacial chemistry in conventional CFRPs by creating concentrated, dispersed and mixed type interphase. Therefore, a detailed study is warranted to establish the interfacial microstructure‐property relationship in CNT modified CFRPs. Experimental results show that the relative improvement in interfacial shear strength (IFSS) and interfacial fracture toughness (G _ic) depends on the microstructure of interphase. It is shown that simultaneous improvement in IFSS and G _ic is possible with certain types of microstructural designs. Moreover, it is observed that IFSS and G _ic are not constant material parameters but both of them show a power‐law type dependence on the applied loading rate. The range of rate sensitivity parameters as a function of interphase type suggests that while concentrated and mixed interphase is more suited to maintain the interfacial integrity, dispersed interphase is beneficial for energy dissipating applications of CFRPs. In addition, IFSS and G _ic exhibit negative rate sensitivity for certain cases. Finally, it is shown that interphase designing using CNT is an excellent tool to accurately tailor the average interfacial properties of CFRP in a broad range of 16‐79 MPa and 100‐453 J m⁻² for IFSS and G _ic, respectively.

中文翻译：

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碳纤维/环氧树脂复合材料的相间工程：界面剪切强度和界面断裂韧性的速率敏感性

从根本上设计聚合物复合材料的界面是一项艰巨的任务。在这里，我们展示了一种使用碳纳米管（CNT）改造碳纤维/环氧树脂复合材料（CFRP）中相间微观结构的策略。CNT的引入通过产生浓缩，分散和混合型界面，改变了常规CFRP中的界面力学和界面化学。因此，有必要进行详细的研究以建立CNT改性CFRP中的界面微结构与性质的关系。实验结果表明，界面抗剪强度（IFSS）和界面断裂韧性（G _ic）的相对提高取决于相的微观结构。它被示出在IFSS并且同时改进ģ _IC某些类型的微结构设计是可能的。此外，可以观察到，IFSS和ģ _IC不是恒定的材料参数，但它们两者的显示上所施加的负荷率幂律型依赖性。速率敏感度参数的范围作为相间类型的函数表明，虽然浓缩和混合相间更适合于保持界面完整性，但分散相间对于CFRP的消能应用是有益的。此外，IFSS和ģ _IC表现出对某些情况下负率的灵敏度。最后，结果表明，使用CNT进行相间设计是一种出色的工具，可以准确地在16-79 MPa和100-453 J m ^-2的宽范围内精确调整CFRP的平均界面性能为IFSS和ģ _IC分别。