The mechanism of shear thickening fluid with nanoparticles applied to liquid armor

Shear thickening fluid (STF) has been reported that it can be applied in defensive and protective equipment, however, to meet the protection requirements for typical ballistic threats, approximately 20-50 layers of fabric are required. The resulting bulk and stiffness of the armor limits its comfort, and has restricted its application primarily to torso protection. Utilization of this shear thickening characteristic, the ballistic protection capability afforded by fabricated, flexible body armor can be enhanced tremendously. The ballistic protection properties of this complex system can be predicted or controlled only if the mechanism is fully understood. But the mechanism of shear thickening is still a matter of debate. It has been ascribed either to an order-disorder transition or to the formation of hydroclusters, however, our research verifies that the hydrogen bond might play an important role on the forming of STF. From our results, it is possible to interpret the occurrence of shear thickening behavior in terms of the shear-induced structure of the suspension once the critical shear strain is reached. The shear -induced structure can only be obtained for the suspension system with intensive hydrogen bonding within the system. The degree of shear thickening also depends on the concentration and temperature of the system.