Warp-knitted spacer fabric flexible composites with high stability and low-velocity impact resistance infused by flock-reinforced shear thickening gel

Flexible protective materials with suitable properties are necessary for personal low-velocity impact (LVI) protection. Flock-reinforced shear thickening gel (FRSTG) can absorb energy through its state transition, thereby showing great potential in applications for LVI protection. However, the unstable state of FRSTG with a slight flow behavior challenges its LVI-resistant evaluation and in-depth development in use. Herein, three-dimensional (3D) warp-knitted spacer fabric (WKSF) composites were obtained by infusing FRSTG in high proportions (≥75%). FRSTG was observed to be stably and randomly distributed in the spacer layer of the WKSF, and the desirable flexibility of the composites was confirmed. The LVI protection effect of FRSTG was better than that of shear thickening gel at the same composite ratio, and the composite with an 83% FRSTG proportion absorbed more than 80% of the impact energy. Besides, FRSTG dominated the composites, showing enhanced responsiveness to the impact with increased velocity. Accordingly, this study constructed stable and LVI-resistant 3D flexible composites with FRSTG as the main functional component, which provided new ideas for the development of wearable protective equipment.