Strength and Fracture Toughness of Polyurethane Elastomers Modified with Carbon Nanotubes

Very small additions of single-wall carbon nanotubes produce an anomalous change in the mechanical properties of a cross-linked polyurethane-amide-urea elastomer containing 10% of polyamide-6: its elastic modulus and ultimate stress reveal local maxima at a nanofiller content of hundredths and thousandths of a percent. Previously, the behavior of the elastic modulus was simulated reasoning from the formation of an intermediate phase layer in the elastomer at particle contact boundaries. Here, on the same basis, we simulate the behavior of its strength as a function of nanotube concentration and consider crack models accounting for the influence of nanotubes on the crack tip zone and fracture toughness.