High Strain-Rate Response of Polyurethane-Clay Nanocomposites and Their Use for Blast Applications Available to Purchase

The dispersion of strong nanoscale building blocks into polymers may result in nanocomposites that can mimic the structural and mechanical properties of advanced materials found in nature. In this study, exceptionally high strength and stiffness (in-plane modulus: 270 GPa) clay nanoparticles are used to synthesize polyurethane-clay nanocomposites with enhanced mechanical properties using a layer-by-layer (LBL) technique. The LBL technique allows spatial and orientational control of these clay nanoparticles within the polymer matrix at the nano-scale. Moreover, the structure of LBL manufactured nanocomposites resembles the structure of naturally occurring tough biocomposite Nacre. A series of nanocomposite films with a wide range of volume fractions of clay nanoparticles was manufactured and investigated at low and high strain rates in uniaxial tension and compression deformation states respectively. The growth of these films in the thickness direction was enhanced by replacing alternate layers of MTM nanoparticles with (poly) acrylic acid. Thick samples for the uniaxial compression tests were made by hot-pressing several of these films together. The nanocomposites demonstrated an increasing yield strength and stiffness with volume fractions of MTM nanoparticles. The nanocomposites, at high-strain rate compression, showed a rapid strain hardening with true stresses as high as 0.45 GPa at a strain of 0.8. The incorporation of clay nanoparticles resulted in a plastic deformation leading to large energy dissipation which makes these materials suitable for applications in increasing the survivability of structures under blast loadings.