Use of pressure sensitive adhesives to create flexible ballistic composite laminates from UHMWPE fabric

Fiber reinforced composites (FRC) have been widely used for ballistic resistance where hot resin melt is infused into the fabric layers and cured to form the composite. Here, we explore the use of pressure-sensitive adhesive (PSA) and its cold lamination as a simple, rapid and inexpensive method to integrate plain-weave UHMWPE and demonstrate that these composites have attractive ballistic performance. Simple compression lamination of 22 layers of fabric with interlay of PSA, for 1 min at 4 or 8 MPa, was able to confer the ability to stop 9 mm bullets shot at ~357 m/s. Increasing the processing pressure results in an increase of inter-ply bonding strength significantly while only affecting the bending stiffness slightly. It also results in an increase in energy absorption of laminate which leads to smaller backface signature and volume and better ballistic performance. They are also more flexible, thinner and lightweight compared with hot melt FRC.