Interfacial reinforcement of aramid composites through amino SiO2 interphase for ballistic application

The aramid fiber reinforced polyurethane composites (AF@PU), which exhibit high strength and lightweight characteristics, have attracted widespread concerns for advanced personal protective systems. However, the interface is essential to influence the stress transfer efficiency but frequently overlooked. In this work, polydopamine and γ-aminopropyltriethoxysilane modified SiO2 (m-SiO2) were utilized to strengthen the interface. Attributing to the strong bonding strength between fibers and polymer resins improved by m-SiO2 at the interface, the tensile, flexural, and compressive strength of m-SiO2/AF@PU are maximally increased. The deposition of abundant m-SiO2 enhances the interface roughness, the interfacial peeling strength of the m-SiO2/AF@PU is increased by 490.4%, and the interlaminar shear strength is increased by 51.1%. In addition, m-SiO2/AF@PU demonstrates the maximal energy absorption value; the ballistic limit velocity is improved from 449.8 m s−1 of AF@PU to 508.5 m s−1 of m-SiO2/AF@PU. This work highlights the interface strengthening and ballistic performance, thus providing an efficient guideline for the design of next-generation fiber reinforced polymer resin composites.