Gradient shear thickening gel/Kevlar fabric multi-layer armor with enhanced impact attenuation property

Realizing highly-efficient energy absorbing performance in soft body armor, yet with lightweight feature, has always been an eternal subject for personal protective equipment. This work reports a gradient-stacked shear thickening gel (STG)/Kevlar (GS-STG/Kevlar) fabric multi-layer armor with both lightweight feature and excellent impact attenuation performance. Firstly, STG is prepared by mechanical blending and chemical crosslinking and then coated on Kevlar fabrics, and afterwards STG-coated multi-layer Kevlar fabrics with gradient STG distribution in the thickness direction are fabricated. Single yarn pull-out test demonstrates that the friction between Kevlar yarns is greatly increased after STG treatment. Moreover, tribological testing also indicates that the friction coefficient of Kevlar fabrics is improved by coating STG. Furthermore, low- and highspeed impact experiments are conducted, and the results demonstrate that the GS-STG/Kevlar fabric composite exhibits the best impact attenuation property when compared with multilayered Kevlar fabrics and uniformly stacked STG/Kevlar fabrics under the same impact conditions. The increased friction and stiffening effect by STG, and the gradient stacking strategy are responsible for the great improvement in the impact attenuation performance of GS-STG/Kevlar fabric multi-layer armors. This study provides an effective methodology for achieving soft body armors with lightweight and high impact attenuation properties for personal impact protection.