Tailoring interfacial architectures in aramid fiber composites: Integrated gains in mechanical strength, dielectric performance, and thermal stability

Aramid fiber composites, as high-performance materials, are widely used in aerospace, military and other fields. As the “bridge” connecting the fiber and resin, the interface directly determines the overall performance of the composite material. In this work, as one of the representatives of thermosetting high-performance resins, benzoxazine-phthalonitrile (BA-Ph) resin was selected as a resin matrix for aramid composites because of its low-temperature autocatalytic properties, thermal stability and chemical resistance. To enhance interfacial compatibility, aramid fibers were synergistically modified via interfacial engineering of polydopamine@polyethyleneimine (PDA@PEI) co-crosslinked networks. The modified fibers were subsequently integrated with BA-Ph resin to fabricate composite laminates. The results demonstrated that the synergistic PDA/PEI modification improved interfacial adhesion, enabling efficient stress transfer between fibers and the matrix. The AF@(PDA + PEI) composite exhibited improved thermal stability and mechanical properties compared to the unmodified material. Notably, the interlaminar shear strength increased by 50.53 % (47.72 MPa) and the impact strength rose by 77.32 % (78.64 MPa), demonstrating that the bimolecular synergistic effect at the interface effectively achieves high strength and toughness of the composites. More importantly, the surface-grafted functional groups on the aramid fibers actively promoted benzoxazine resin curing. This interfacial engineering provides novel insights into designing and optimizing resin composites.