Healable carbon fiber reinforced epoxy composites: Synchronous healing of matrix and interface damage

Abstract Thermosetting composites are a range of high‐performance materials with important applications in multiple fields. However, inaccessible damage such as microcracks ingress from the environment may appear with long term use. Over time, the micro‐damage further expands and leads to material failure. The damage includes the interface damage and the matrix damage. Therefore, the healing technology of composites needs to respond and heal the micro‐damage of the interface and resin in the composites synchronously. In this work, siloxane dynamic bond was introduced into matrix and interface respectively. Specifically, a new type of crosslinker containing polysiloxane was synthesized and used to cure epoxy resin. Polyhedral oligomeric silsesquioxane was modified on the surface of carbon fibers (CFs) by sizing method. The prepared resin showed great mechanical properties and thermal stability, while the mechanical strength and surface activity of the CFs were also improved. Due to siloxane chain exchange reaction, matrix and interface could healing synchronously with good healing efficiency. Furthermore, the composites could retain about 65% of their original mechanical properties after healing multiple times. Composites realized synchronous healing of the resin matrix and the interface and laid foundation for extending the service life and performance of advanced resin‐based composites.