carbon nanotubes; foam; impact; layers; helmets; pressure; infusions; polymers; RESILIENCE; composite materials; FABRICATION; IMPACT TESTS; cushioning; MICROSTRUCTURE; NANOSTRUCTURES; STRAIN (MECHANICS); TEST AND EVALUATION; stress strain relations; PROTECTIVE EQUIPMENT; THERMAL STABILITY; PERFORMANCE (ENGINEERING); polyurethane; phase separation; fabrication; arrays; Freeze drying; COMPRESSION;