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Laboratory-scale Investigation of the Influence of Ageing on the Performance and Sensitivity of an Explosive Containing ϵ-CL-20

Propellants, Explosives, Pyrotechnics

Gottfried, Jennifer L.; Pesce-Rodriguez, Rose A.; Farrow, Darcie F.; Dellinger, Jennifer D.

The performance and sensitivity of aged composite explosives based on the epsilon polymorph of hexanitrohexaazaisowurtzitane (ϵ-CL-20) have been evaluated with the laser-induced air shock from energetic materials (LASEM) technique using only milligram quantities of material. The LASEM results demonstrated reduced explosive performance (i. e., lower estimated detonation velocities) and higher sensitivity to ignition with increasing ageing. Chemical analysis of the explosive formulation subjected to ambient and accelerated aging was conducted to help understand the LASEM results. The Fourier Transform Infrared (FTIR) spectra revealed no evidence for conversion to lower-energy polymorphs. Based on the desorption gas chromatography/mass spectrometry (D-GC/MS) results, the observed decrease in performance and increase in sensitivity for the explosive powder aged at 100 °C (relative to ambient and 70 °C aging) have been attributed to changes related to solvent inclusions in the molding powders.

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TYPE Journal Article YEAR 2018
ScopusOSTIDOI

Energy Transfer between Coherently Delocalized States in Thin Films of the Explosive Pentaerythritol Tetranitrate (PETN) Revealed by Two-Dimensional Infrared Spectroscopy

Journal of Physical Chemistry B

Ostrander, Joshua S.; Knepper, Robert; Tappan, Alexander S.; Kay, Jeffrey J.; Zanni, Martin T.; Farrow, Darcie F.

Pentaerythritol tetranitrate (PETN) is a common secondary explosive and has been used extensively to study shock initiation and energy propagation in energetic materials. We report 2D IR measurements of PETN thin films that resolve vibrational energy transfer and relaxation mechanisms. Ultrafast anisotropy measurements reveal a sub-500 fs reorientation of transition dipoles in thin films of vapor-deposited PETN that is absent in solution measurements, consistent with intermolecular energy transfer. The anisotropy is frequency dependent, suggesting spectrally heterogeneous vibrational relaxation. Cross peaks are observed in 2D IR spectra that resolve a specific energy transfer pathway with a 2 ps time scale. Transition dipole coupling calculations of the nitrate ester groups in the crystal lattice predict that the intermolecular couplings are as large or larger than the intramolecular couplings. The calculations match well with the experimental frequencies and the anisotropy, leading us to conclude that the observed cross peak is measuring energy transfer between two eigenstates that are extended over multiple PETN molecules. Measurements of the transition dipole strength indicate that these vibrational modes are coherently delocalized over at least 15-30 molecules. We discuss the implications of vibrational relaxation between coherently delocalized eigenstates for mechanisms relevant to explosives.

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TYPE Conference Poster YEAR 2017
ScopusOSTIDOI

Pressure dependence of electronic states in secondary explosives: comparison between bulk and air/explosive interface

Farrow, Darcie F.; Farrow, Darcie F.; Kohl, Ian T.; Kohl, Ian T.; Rupper, Stephen G.; Rupper, Stephen G.; Alam, Mary K.; Alam, Mary K.; Martin, Laura E.; Martin, Laura E.; Fan, Hongyou F.; Fan, Hongyou F.; Bian, Kaifu B.; Bian, Kaifu B.; Knepper, Robert; Knepper, Robert; Marquez, Michael P.; Marquez, Michael P.; Kay, Jeffrey J.; Kay, Jeffrey J.

Abstract not provided.

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TYPE Conference Poster YEAR 2015
OSTI
Results 1–25 of 39
Results 1–25 of 39