Cyclic healing of delamination in amine-epoxy vitrimer carbon fiber composites

• Epoxy-amine vitrimer composites show intrinsic self-healing under thermal cycles • Vitrimer composites offer reprocessability and durability for structural applications • Healing efficiency peaks at 61.2% at 195 °C for 30 minutes under 12 MPa pressure • ILSS recovery declines with repeated cycles due to cumulative damage and resin loss • Healing behavior is governed by a balance between mobility and thermal degradation This work investigates the self-healing behavior of epoxy-amine vitrimer composites under controlled delamination and healing protocols. Composites were prepared via Vacuum-Assisted Resin Infusion (VARI), curing overnight for 12 hours at ambient temperature, followed by a stepwise post-curing cycle up to 180°C. The interlaminar shear strength (ILSS) was assessed by Short Beam Shear (SBS) tests, in accordance with ASTM D2344, using a 3-point bending configuration. The damaged composite specimens by delamination caused by the interlaminar shear strength were then healed, and the maximum shear stress ( τ I L S S ) was calculated for pristine and healed specimens. The specimens were healed under controlled thermal conditions, 180°C and 195°C, under a constant pressure of 12 MPa for varying dwell times of 15, 30, and 60 min. The effectiveness of the repair was assessed for those three time intervals and both temperatures. The highest healing efficiency (61.2 %) was achieved at 195°C for 30 minutes, demonstrating optimal matrix mobility and interfacial recovery. The findings indicate that the healing efficiency is influenced by a complex relationship between time and temperature, requiring a balance between adequate network mobility and the prevention of thermal degradation. This work demonstrates the feasibility of epoxy resin-based vitrimers as inherently healable matrices for high-performance carbon fiber composites. The ability to achieve moderate-to-high healing efficiencies across realistic repair conditions supports their potential for structural applications requiring durability, reprocessability, and reduced maintenance cycles.