Characterization of α- and β-RDX Polymorphs in Crystalline Deposits on Stainless Steel Substrates

Figueroa-Navedo, Amanda M.; Ruiz-Caballero, José L.; Pacheco‐Londoño, Leonardo C.; Hernández‐Rivera, Samuel P.

doi:10.1021/acs.cgd.6b00078

Cited by 22 publications

(32 citation statements)

References 36 publications

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“…1,5 Previous research has concluded that the polymorphic phase of a given material can be affected by a variety of factors, such as the solvent, evaporation rate, mass loading, deposition technique, or substrate. 1,5,6,[19][20][21] Specifically, work on the polymorphic nature of RDX has demonstrated that both the substrate and mass loading can affect the formation of the aand b-RDX. For example, the a-RDX phase can be formed preferentially when depositing an excess amount of material onto the substrate of interest 1,5 as demonstrated in previous research comparing drop cast crystallization and inkjet deposition.…”

Section: Introductionmentioning

confidence: 99%

Polymorphic Phase Control of RDX-Based Explosives

Brady¹,

Argirakis

Gordon

et al. 2017

Appl Spectrosc

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The polymorphic phase of 1,3,5-trinitro-1,3,5-triazine (RDX) was examined as a function of mass loading, solvent, and sample deposition technique. When RDX was deposited at a high mass loading, the vibrational modes in the obtained Raman spectra were indicative of concomitant polymorphism as both the α-RDX and β-RDX phases were present. At low mass loadings, only β-RDX was observed regardless of solvent when using the drop cast crystallization method. However, α-RDX (the thermodynamically stable polymorphic phase observed with visible quantities of the explosive) was observed when RDX deposits were dry transferred. Observation of α-RDX was independent of the initial mass loading or the initial deposition solvent when using the dry transfer methodology. These data indicate that the use of the dry transfer preparation method can be used to successfully prepare RDX-based test articles with the α-RDX phase regardless of the solvent used to initially dissolve the RDX, the initial deposition technique, or the mass loading.

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Section: Introductionmentioning

confidence: 99%

Polymorphic Phase Control of RDX-Based Explosives

Brady¹,

Argirakis

Gordon

et al. 2017

Appl Spectrosc

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“…Figure 2d shows the decay of the IR signals for RDX. The behavior of the area for the band at 1264 cm−1 and the band at 1321 cm−1 (N–NO2 symmetrical stretching [43,44,45,46,47,48]) vs. time are approximately linear. However, the IR intensity decay vs. time is exponential for the 1593 cm−1 band (N–NO2 asymmetrical stretching [43,44,45]).…”

Section: Results and Discussionmentioning

confidence: 97%

Surface Persistence of Trace Level Deposits of Highly Energetic Materials

et al. 2019

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In the fields of Security and Defense, explosive traces must be analyzed at the sites of the terrorist events. The persistence on surfaces of these traces depends on the sublimation processes and the interactions with the surfaces. This study presents evidence that the sublimation process of these traces on stainless steel (SS) surfaces is very different than in bulk quantities. The enthalpies of sublimation of traces of four highly energetic materials: triacetone triperoxide (TATP), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), and 1,3,5- trinitrohexahydro-s-triazine (RDX) deposited on SS substrates were determined by optical fiber coupled-grazing angle probe Fourier Transform Infrared (FTIR) Spectroscopy. These were compared with enthalpies of sublimation determined by thermal gravimetric analysis for bulk amounts and differences between them were found. The sublimation enthalpy of RDX was very different for traces than for bulk quantities, attributed to two main factors. First, the beta-RDX phase was present at trace levels, unlike the case of bulk amounts which consisted only of the alpha-RDX phase. Second, an interaction between the RDX and SS was found. This interaction energy was determined using grazing angle FTIR microscopy. In the case of DNT and TNT, bulk and traces enthalpies were statistically similar, but it is evidenced that at the level of traces a metastable phase was observed. Finally, for TATP the enthalpies were statistically identical, but a non-linear behavior and a change of heat capacity values different from zero was found for both trace and bulk phases.

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“…(k) for TATP, 2,4-DNT, and TNT from the slopes (seeSupplementary Material).Fig.2dshows the decay of the IR signals for RDX. The behavior of the area for the band at 1264 cm −1 and the band at 1321 cm −1 (N-NO 2 symmetrical stretching[42][43][44][45][46][47]) vs. time are approximately linear. However, the IR intensity decay vs. time is exponential for the 1593 cm −1 band (N-NO 2 asymmetrical stretching[42][43][44]).…”

mentioning

confidence: 83%

Surface Persistence of Trace Level Deposits of Highly Energetic Materials

Pacheco‐Londoño¹,

Ruiz-Caballero²,

Ramírez-Cedeño³

et al. 2019

Preprint

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The sublimation enthalpies of four highly energetic materials (HEMs): triacetone triperoxide (TATP), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT) and 1,3,5-trinitrohexahydro-s-triazine (RDX) deposited on stainless steel (SS) substrates were determined by optical fibre coupled-grazing angle probe (GAP) FTIR spectroscopy and thermogravimetric analysis (TGA) for bulk crystaline HEMs samples. The desorption energy of RDX on SS was also studied using grazing angle FTIR microscopy. Metastable phases of 2,4-DNT and TNT were observed when deposited on SS, and their sublimation enthalpies values were obtained by GAP measurements and compared with those for the crystalline phases. The sublimation enthalpies for the alpha phase RDX was also determined by TGA measurements. A layer of crystalline beta phase RDX was observed on SS, and it's sublimation enthalpies was determinate by GAP. PLS calibration curves for the surface concentrations of RDX on SS were generated using GAP to determinate the surface concentration with time at different temperatures.

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Characterization of α- and β-RDX Polymorphs in Crystalline Deposits on Stainless Steel Substrates

Cited by 22 publications

References 36 publications

Polymorphic Phase Control of RDX-Based Explosives

Polymorphic Phase Control of RDX-Based Explosives

Surface Persistence of Trace Level Deposits of Highly Energetic Materials

Surface Persistence of Trace Level Deposits of Highly Energetic Materials

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