  The energy absorption and impact attenuation of low density polyurea (PU)
foams (140 - 220 kg/m3) is presented. The stress-strain behavior, energy
absorption, cushioning efficiency, and energy return (resilience) are measured
at a quasi-static strain rate using an Instron load frame. In addition, the low
velocity impact attenuation of the polyurea foams at 5 J and 7 J impact
energies were investigated according to the American Society for Testing and
Materials (ASTM) test methods F1976. The polyurea foams were then compared with
widely used ethylene vinyl acetate (EVA) and thermoplastic polyurethane (TPU)
foam technologies at similar densities. The PU foams displayed a 5 % increase
in cushioning efficiency and 30 % greater energy absorption over TPU and EVA
foams under quasi-static compression. Under impact testing, PU foams resulted
in a reduction of up to 28.6 % and 36.9 % in peak transmitted impact forces
when compared to EVA and TPU foams of the same thickness (20 mm) at 5 J and 7
J, respectively. These properties should allow these materials to have a wide
range of cushioning/impact applications, especially in protective body and
headgear systems.
