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Title: Ultrafast Chemistry under Nonequilibrium Conditions and the Shock to Deflagration Transition at the Nanoscale

We use molecular dynamics simulations to describe the chemical reactions following shock-induced collapse of cylindrical pores in the high-energy density material RDX. For shocks with particle velocities of 2 km/s we find that the collapse of a 40 nm diameter pore leads to a deflagration wave. Molecular collisions during the collapse lead to ultrafast, multistep chemical reactions that occur under nonequilibrium conditions. WE found that exothermic products formed during these first few picoseconds prevent the nanoscale hotspot from quenching. Within 30 ps, a local deflagration wave develops. It propagates at 0.25 km/s and consists of an ultrathin reaction zone of only ~5 nm, thus involving large temperature and composition gradients. Contrary to the assumptions in current models, a static thermal hotspot matching the dynamical one in size and thermodynamic conditions fails to produce a deflagration wave indicating the importance of nonequilibrium loading in the criticality of nanoscale hot spots. These results provide insight into the initiation of reactive decomposition.
Authors:
 [1] ;  [1] ;  [2] ;  [3]
  1. Purdue Univ., West Lafayette, IN (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Purdue Univ., West Lafayette, IN (United States)
Publication Date:
OSTI Identifier:
1235676
Report Number(s):
LA-UR-14-27916
Journal ID: ISSN 1932-7447
Grant/Contract Number:
N00014-11-1-0466; HDTRA1-10-1-0119; AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 119; Journal Issue: 38; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; explosives; initiation; shock chemistry