Enhanced Interfacial Strength and UV Shielding of Aramid Fiber Composites through ZnO Nanoparticle Sizing

Here, a simple zinc oxide (ZnO) nanoparticle sizing is reported for aramid fibers that simultaneously provides interfacial reinforcement and UV absorption to develop improved fiber-reinforced composites. Through a one-step nanoparticle deposition, the modified aramid fiber showed an increase in interfacial shear strength of 18.9% with the addition of ZnO nanoparticles when tested by single-fiber pullout. The aramid fibers were then treated with a hydrolysis process common to aramid fibers to oxidize the surface and elucidate the importance of oxygen functional groups at the interface. These oxidized fibers proved to further enhance the interface between the fiber surface and nanoparticle, leading to a 33.3% increase relative to the bare fiber. Additionally, due to the absorption properties of ZnO, the retainment of mechanical properties of coated fibers was determined after exposure to an artificial UV light source. After 24 h of exposure, fibers coated with ZnO nanoparticles retained 25% more tensile strength and 21% more modulus than uncoated bare fibers. This work shows that ZnO nanoparticles may serve as a novel, yet simple, multifunctional fiber sizing with which to increase the interfacial strength of aramid fiber composites and improve the resistance to UV irradiation, enabling stronger and more-durable structural fiber composites.