Damage visualization and enhanced interlaminar shear strength of carbon fiber reinforced composites with Ni/PUF/PU@ER microcapsules

Carbon fiber reinforced polymers (CFRP) are utilized in a variety of fields, but they are prone to delamination, which can cause substantial degradation to the properties and limit the usage. Here, Ni/PUF/PU@ER (NPPER) microcapsules were introduced into the composites to improve the interlaminar shear strength (ILSS). The PUF/PU@ER (PPER) microcapsules were first synthesized with epoxy resin as the healing agent, followed by electroless plating to deposit metal Ni on the surface. The microsphere compression tests demonstrated that the NPPER had superior strength (41.7 MPa) compared to the PPER. When 20 w.t.% PPER was added, the ILSS reduced to 32.8 MPa compared with the ILSS of the original specimen (36.7 MPa), and the healing efficiency increased to 81.8 %. However, due to the robustness of the NPPER, the ILSS increased to 40.3 MPa with 5 w.t.% NPPER, which was 9.8 % higher than that of the original specimen, and the highest healing efficiency was 52.0 % with 20 w.t.% NPPER. Furthermore, the NPPER with damage visualization was prepared using epoxy resin and 2′,7′-Dichlorofluorescein as core materials, which can be utilized to imply the occurrence and healing of damage by the change of color, promoting the development of intelligent and high-performance self-healing CFRP.