Light shear thickening fluid (STF)/Kevlar composites with improved ballistic impact strength

Shear thickening fluids (STFs) have been developed for various applications such as body armor, viscoelastic dampers, and sports equipment. In this paper, the preparation and rheological properties of an STF are discussed. STF/Kevlar composites were made using ethanol as the cosolvent. The physical properties of the composites were determined by ballistic penetration, drop-tower, and yarn pull-out tests. The ballistic penetration was tested at a projectile velocity of 180 m/s. The ballistic penetration tests showed that adding the STF could obviously increase the energy dissipation. In addition, the weight of the composites may be reduced by 37% while their ballistic resistance is maintained. The knife drop-tower tests showed that adding the STF may improve the energy absorption by 20%. The yarn pull-out test demonstrated that the maximum pull-out force of the STF/Kevlar composites is 3.17 times that of neat Kevlar. The enhancements in the physical properties were apparently associated with the addition of the STF.