Effect of a Halloysite-polyurethane nanocomposite interlayer on the ballistic performance of laminate transparent armour

Polyurethanes are commonly used in transparent armour systems to increase the survivability, blast resistance, multi-hit resistance, and fragment containment of multi-layered systems. The high tensile-ductility, fracture toughness, and self-healing ability are key factors that determine the performance of polyurethanes under high-strain-rate conditions. Here, we have investigated the potential of transparent nanocomposites interlayers based in Halloysite (HNT)-reinforced polyurethane within transparent armour systems. The polyurethane prepolymer is partially silane end-capped and filled with only 0.8 wt% acid-treated HNTs. Ballistic testing results showed an increase on the ballistic limit, from 457 to 491 m/s, with the change from a neat polyurethane interlayer to the nanocomposite. Molecular dynamics simulations were conducted to further investigate the effect of HNTs in the immiscibility and mobility of the segmented structure of the polyurethane. Our results demonstrate that the significant improvement in the ballistic performance of the nanocomposite interlayers were not due to the small concentration of HNTs acting as simple reinforcing phase, but rather their influence in the formation of the microstructure of the matrix polymer.