Soft armor materials constructed with Kevlar fabric and a novel shear thickening fluid

This study presents the dynamic stab resistance and quasi-static mechanical properties of soft armor materials constructed with Kevlar fabric impregnated with a novel shear thickening fluid (STF) composed of silica microsphere and ionic liquids (ILs). Rheological results indicate that this STF presents a unique double continuous shear thickening behavior and good conductivity. Both the stab resistance and mechanical properties of the Kevlar fabric are enhanced significantly due to the presence of the STF. With increasing the addition of STF, the stab resistance of the STF-processed Kevlar fabrics (STKF) is enhanced, and the optimal stab resistance is obtained when the STKF contains 34.89 wt % STF. By comparison with the neat Kevlar fabric, the maximum friction between the yarns in the STKF increases by dozens of times, and the tensile strength of the STKF and yarn increases by approximately 2 times and 1.5 times, respectively. Tensile and pull-out tests demonstrate that both filaments and yarns are restrained for the unique double continuous shear thickening of the STF. Furthermore, the STKF has conductivity and the electrical resistance of it has high sensitivity to the applied deformation. The electromagnetic interference shielding of the STKF was as high as 27 dB. These provide a potential to exploit the novel next generation of soft armor with both excellent protective performance and intelligent wearable property.