Interface and mechanical properties of combined surface‐treated carbon fiber fabrics/polyimine laminates: Experiments and numerical simulations

Abstract Carbon fiber reinforced polyimine (CF/PI) composites had promising applications due to their flame retardancy and ease of recyclability. However, the mechanical properties of CF/PI are generally insufficient, and optimizing the interface between carbon fiber (CF) fabrics and polyimine (PI) matrix could effectively solve this problem. The interfacial bonding between CF fabrics and the PI matrix was enhanced by a combination of CF fabrics pre‐treatment and grafting with the silane coupling agent (APTMS). CF/PI laminates were prepared by the “pre‐fabrication‐lamination” method to optimize the production cycle. Interlaminar delamination failure of CF/PI laminates was analyzed using the cohesive element method. The experimental results showed that the combination of pre‐treatment and grafted APTMS treatment increased the impact strength, flexural strength, and interlaminar shear strength (ILSS) of CF/PI laminates by 227.5%, 158.2%, and 259.8%, respectively. The simulation results showed excellent agreement with the experimental results. The scanning electron microscopy morphology of the fracture surface showed that delamination was the primary damage mechanism, which was consistent with the cohesive element simulation delamination. In this paper, a strategy for the optimization of the interface between CF fabrics and the PI matrix was proposed for the first time, and reliable numerical simulation results were provided. Highlights CF/PI laminates were produced by “pre‐fabrication‐lamination”. Enhanced CF/PI interface by CF fabrics pre‐treatment and APTMS grafting. CF/PI laminates showed significant improvements in impact strength, flexural strength, and ILSS. Cohesive element method accurately predicts interlaminar delamination. The error between experimental and numerical simulation results was less than 5%.