High strain rate fracture and C-chain unraveling in carbon nanotubes

Nanotube behavior at high rate tensile strain (similar to 1 MHz) is studied by molecular dynamics using a realistic many-body interatomic potential. The simulatins performed for single and double-walled nanotubes of different helicities, and al different temperatures, show that nanotubes have an extremely large breaking strain. It decreases somewhat with increasing temperature and smaller strain rate, while the influence of helicity is very weak. At later stages of fracture, the nanotube fragments are connected by a set of unraveling monoatomic chains. The chains 'compete' with each other for carbon atoms popping out of the original tube segments. The interaction between chains eventually leads to a single chain, which grows up to hundreds of atoms in length before its breakage. (C) 1997 Elsevier Science B.V.