Thermoplastic polyurethane nanocomposites produced via impregnation of long carbon nanotube forests

TPU was infiltrated into vertically aligned, 3.5 mm-long MWNT forests to produce continuously reinforced anisotropic nanocomposites, and thermomechanical and electrical testing has revealed multifunctionality which shows promise for numerous applications. A 1000% increase in the storage modulus at 70 °C was observed as compared to the neat TPU, and these continuously aligned composites showed electrical conductivity two orders-of-magnitude greater (≈1.5 S · cm^-1) than randomly aligned composites prepared using CNTs from these forests. The heightened improvement for the continuously reinforced composite appears to be owed to the extremely high aspect ratio of these CNTs and the interconnected network which remains after infiltration. Polyurethane mechanical properties were dramatically enhanced by the addition of 6 wt.-% high-aspect-ratio carbon nanotubes. Oriented nanocomposites showed conductivities of 1 S · cm^-1 without any obvious influence due to the direction of nanotube alignment.