From Passive Enhancement to Active Repair: Research Progress on the Collaborative Strategy of CFRP Interface Engineering Addressing Environmental Aging

Carbon fiber reinforced polymer composites (CFRP) are widely used in high-performance equipment due to their exceptional specific strength and design flexibility. However, the aging behavior of the fiber-matrix interface under environments such as heat and humidity, salt spray, UV and thermal oxidation affects the long-term service reliability of the structure. To enhance interface durability, a review is provided on the system comprising aging mechanisms, characterization methods, enhancement technologies and repair strategies. The interface damage resulting from various mechanisms, including water diffusion, photolysis and thermal oxidation in four specified environments, is analyzed. The application of multi-scale characterization techniques for evaluating interface performance is also summarized. The enhancement theories, mainly based on physical forces, chemical bonds, interfacial layer structures and transition effects, were systematically reviewed. Furthermore, strategies involving surface energy regulation, interfacial structure strengthening and graft functionalization were introduced. Given that traditional modifications cannot reverse interface damage, the focus has shifted from ''passive'' enhancement to ''active'' self-repair. Advanced self-repair strategies for the interface, including vitreoid materials, thermoplastic polymers, microcapsules and vascular systems, are explored. Finally, the discussion shifts from ''technology enumeration'' to ''paradigm induction'', defining the principles and characteristics of extrinsic and intrinsic repair. The mechanisms of intrinsic repair, including supramolecular networks, dissociation and association, are analyzed, providing a theoretical framework and design concepts for the development of ''self-sensing, self-diagnosis, self-repair'' materials.