Polymorphic Phase Control of RDX-Based Explosives

Brady, John J.; Argirakis, Brittney L.; Gordon, Alexander D.; Lareau, Richard T.; Smith, Barry T.

doi:10.1177/0003702817712259

Cited by 10 publications

(6 citation statements)

References 22 publications

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“…The images shown in Figure S1 of the Supporting Information were collected by using a Zeiss GeminiSEM 300 operating with a 1.1 kV accelerating voltage and secondary electron detector. For these thin films, α-RDX is expected to be the dominant polymorph; , the FTIR spectrum shown in Figure supports this conclusion …”

Section: Methodssupporting

confidence: 54%

Mode-Selective Vibrational Energy Transfer Dynamics in 1,3,5-Trinitroperhydro-1,3,5-triazine (RDX) Thin Films

et al. 2021

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The coupling of inter-and intramolecular vibrations plays a critical role in initiating chemistry during the shock-to-detonation transition in energetic materials. Herein, we report on the subpicosecond to subnanosecond vibrational energy transfer (VET) dynamics of the solid energetic material 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) by using broadband, ultrafast infrared transient absorption spectroscopy. Experiments reveal VET occurring on three distinct time scales: subpicosecond, 5 ps, and 200 ps. The ultrafast appearance of signal at all probed modes in the mid-infrared suggests strong anharmonic coupling of all vibrations in the solid, whereas the long-lived evolution demonstrates that VET is incomplete, and thus thermal equilibrium is not attained, even on the 100 ps time scale. Density functional theory and classical molecular dynamics simulations provide valuable insights into the experimental observations, revealing compression-insensitive time scales for the initial VET dynamics of high-frequency vibrations and drastically extended relaxation times for low-frequency phonon modes under lattice compression. Mode selectivity of the longest dynamics suggests coupling of the N−N and axial NO 2 stretching modes with the long-lived, excited phonon bath.

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Section: Methodssupporting

confidence: 54%

Mode-Selective Vibrational Energy Transfer Dynamics in 1,3,5-Trinitroperhydro-1,3,5-triazine (RDX) Thin Films

et al. 2021

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“…S1 in the Supporting Information (SI), were collected using a Zeiss GeminiSEM 300 operating with a 1.1 kV accelerating voltage and using the secondary electron detector. For these thin films, α-RDX is expected to be the dominant polymorph; 19,42 the FTIR spectrum shown in Fig. 1 supports this conclusion.…”

Section: A Experimentalmentioning

confidence: 55%

Mode-Selective Vibrational Energy Transfer Dynamics in 1,3,5-Trinitroperhydro-1,3,5-Triazine (RDX) Thin Films

Cole-Filipiak¹,

Knepper²,

Wood³

et al. 2021

Preprint

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Herein, we report on the sub-picosecond to sub-nanosecond vibrational energy transfer (VET) dynamics of the solid energetic material 1,3,5-trinitroperhydro-1,3,5-triazine (RDX) using broadband, ultrafast infrared transient absorption spectroscopy. Experiments reveal VET occurring on three distinct timescales: sub-picosecond, 5 ps, and 200 ps. The ultrafast appearance of signal at all probed modes in the mid-infrared suggests strong anharmonic coupling of all vibrations in the solid whereas the long-lived evolution demonstrates that VET is incomplete, and thus thermal equilibrium is not attained, even on the hundred picosecond timescale. Mode-selectivity of the longest dynamics suggests coupling of the N–N and axial NO<sub>2</sub> stretching modes with the long-lived, excited phonon bath.

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“…Powder XRD was performed to investigate if spray drying had any effect on the crystalline phase of the source RDX, as RDX is known to have a stable and second metastable polymorph at room temperature (α and β, respectively). − Figure shows the powder XRD patterns comparing the source material (Class 5 RDX) to the ultrafine spray-dried RDX powder. The first important parameter from the XRD data shows that RDX retains the thermally stable, orthorhombic polymorph (α-RDX) after spray drying.…”

Section: Resultsmentioning

confidence: 99%

Microstructural and Sensitivity Changes of Neat, Spray-Dried RDX

et al. 2022

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Spray drying has recently gained interest in the high explosives (HE) community for the production of novel nanocomposites and wellcontrolled particle size distributions. However, there is a dearth of information on spray-dried, neat energetic materials. In this work, we correlate the spray drying production parameters to the resulting microstructure and handling sensitivity properties of neat RDX. We demonstrate the capability to fine-tune the particle size distributions for "nanopowder" spray-dried RDX, as well as larger particle size distributions by simply changing the spray dryer setup. We also investigate other physical and chemical changes that RDX undergoes after being processed with spray drying. We characterize these changes with scanning electron microscopy, X-ray diffraction, ultrahigh-performance liquid chromatography, and small-scale sensitivity tests. Interestingly, although the phase and chemical properties are similar before and after spray drying, small-scale sensitivity testing reveals that size reduction of RDX does not follow the typical HE desensitization trends, generally observed for other energetic materials.

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Polymorphic Phase Control of RDX-Based Explosives

Cited by 10 publications

References 22 publications

Mode-Selective Vibrational Energy Transfer Dynamics in 1,3,5-Trinitroperhydro-1,3,5-triazine (RDX) Thin Films

Mode-Selective Vibrational Energy Transfer Dynamics in 1,3,5-Trinitroperhydro-1,3,5-triazine (RDX) Thin Films

Mode-Selective Vibrational Energy Transfer Dynamics in 1,3,5-Trinitroperhydro-1,3,5-Triazine (RDX) Thin Films

Microstructural and Sensitivity Changes of Neat, Spray-Dried RDX

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