New insight into the formation of carbon structures in the early stages of detonating TATB

Carbon-rich explosives such as TATB decompose into small molecules and yield an excess of carbon. In a phenomenological approach, experimentally observed carbon nanoparticles form from excess carbon, but the atomic-scale process leading to this excess of carbon is still to be elucidated. To this aim, we considered representative sizes of TATB samples around the von Neumann (VN) or around the Chapman-Jouguet (CJ) states, representing the beginning and the end, respectively, of the reaction zone in the ZND detonation model. The constant-volume, adiabatic decomposition of TATB and the chemical evolution were studied by means of Reactive Molecular Dynamics. The simulations showed the formation of the expected small molecules, as well as that of a carbon-rich foam in which medium-sized units of graphene and sp³-carbon nucleate. Then, within the foam channels, these units can connect to each other, disconnect, and reconnect… until they form an extended network of pure carbon. After 50+ ns, the extended structure does not evolve much, and this form factor remains far from that of compact nanoparticles. Still, the expansion phases of the detonation and their effects on the foam and its pure carbon units are to be addressed in a study coming next.