Role of ZnO nanowire arrays on the impact response of aramid fabrics

High performance aramid fabrics are extensively used in personal body armor to provide soft, lightweight, yet effective ballistic protection. Grafting nanomaterials on the surface of aramid fibers is one of the promising methods developed for enhancing and tailoring the performance of the fabrics and their composites. Recently, it was shown that growth of ZnO nanowires on aramid fibers drastically improves fabric interyarn friction, as an energy dissipation mechanism. In this work, the influence of ZnO nanowires on the ballistic response of aramid fabrics is evaluated. Intermediate velocity (22–40 m/s) impact tests are conducted on the fabric targets using a gas gun setup. The setup was equipped with a shock accelerometer for measuring contact force and two photoresistors for accurate velocity measurement of the projectile just before impact. As a result of the integration of ZnO nanowires, the maximum impact force of a single aramid fabric is increased approximately 66% in a specific range of impactor velocity. It is postulated that in this velocity range yarn pullout is the dominant failure mechanism of the fabrics for the specific fabric and projectile geometry used in this study. Furthermore, post-test imaging of the fabric targets confirms the efficacy of ZnO nanowires in enhancing impact resistance of aramid fabrics as a result of increased interyarn friction and limiting yarn mobility.