Nanocarbons produced by nitromethane detonations in air: Insights into the role of H2O and O2

Abstract

X-ray scattering and transmission electron microscopy carried out on unpurified soot recovered from open air detonations of a liquid explosive mixture of nitromethane (95 (v/v) % and diethylenetriamine 5 (v/v) % sensitizer determined primary particles possessing a hollow spherical core (davg. = 6.9 nm) coated in a sp2-hybridized carbon shell of ~ 4.2 nm thick. Similar nanophase carbons have been previously reported in studies on closed chamber detentions of composition B in air. Given the noted changes in charge size, explosive composition, and peak temperature and pressure between the two detonations, we hypothesize the formation of the nanocarbons are attributed to excess H2O (detonation byproduct and/or atmospherically-derived) and atmospherically-derived O2. The H2O is hypothesized to be the determining component leading to the formation of non-planar (curved), sp2-hybridized carbon frameworks, necessary for assembly into spherical particles. Excess O2 produces after-burn, an oxidizing environment sufficient to possibly create the interior voids.