Enhancement of the ballistic performance of aramid fabric with polyurethane and shear thickening fluid

Conventionally, the shear thickening fluid (STF) is used to improve the ballistic performance of aramid fabric because its shear thickening property increases the friction of inter-yarns. However, intuitively, enhancing the inter-yarn adhesion is an easier method. In this study, the adhesive polyurethane (PU) was utilized. The aramid fabrics impregnated with STF, the composite of STF and PU (STF-PU), and PU were compared in terms of the resistance to single yarn pull-out, the flexibility of fabric and the high-velocity impact test, respectively. Due to the robust adhesion of PU, comparing with STF/aramid fabric, a small amount of PU within STF-PU could strengthen the resistance of inter-yarn relative motion significantly and decrease mass loading intensively. Meantime, the flexibility had a little compromise due to unique heterogeneous structure in striking contrast with PU/aramid whose flexibility was impaired extremely. When it came to the high-velocity impact test, STF-PU/aramid showed outright advantages over STF/aramid and PU/aramid composite. It was also illuminated that excessively strong resistance to the yarn mobility was adverse for the high-velocity impact. Confidently, this work provides a new avenue in the development of flexible armor.