The Low‐Temperature High‐Pressure Phase Diagram of Energetic Materials: I. Hexahydro‐1,3,5‐Trinitro‐s‐Triazine

The reaction phase diagram of hexahydro‐1,3,5‐trinitro‐s‐triazine (RDX) has been studied as a function of temperature and pressure by Raman spectroscopy to 29 GPa and temperatures ranging from 4 to 298 K. Three stable phases (α, γ, and δ) have been found and their phase stabilities have been investigated. Phase boundaries were studied as a function of pressure and temperature, permitting a delineation of the various polymorph stability fields. A pressure–temperature reaction/phase diagram is constructed from the results of this study and compared to previous high temperature work.     

Theoretical Study of Mechanism and Kinetics of the Reaction of NO2 with s‐Triazine

The decomposition of nitramines explosives have been of great interest for a long time. However, theoretical investigations have concentrated mainly on unimolecular decomposition whereas bimolecular reactions have received only little attention. In this paper, the bimolecular reaction between NO₂ with s‐triazine (TAZ), which is an initial product during the decomposition process of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) is investigated. The structures and potential energy surface (PES) are explored at B3LYP/6‐31G(d,p) and B3P86/6‐31G(d,p) levels, and the energies are refined using the CCSD(T)/cc‐pVTZ methods. The mechanism of the reaction is analyzed. Quantum chemistry calculations reveal that the title reactions possess small barriers that can be similar to, or smaller than that of initial decomposition reactions of RDX, which suggests that bimolecular reactions are also of great importance, and should be further investigated. Moreover, the kinetics were investigated to verify the proposed mechanism of the reaction.     

Theoretical Prediction of Physicochemical Properties,Performances and Sensitivities of some New Derivatives of Dinitro Triazolyl Triazine

In this paper, important properties of some new derivatives of dinitro triazolyl triazine as novel heterocyclic energetic compounds are evaluated and discussed by using some reliable models. The predicted properties are also compared with octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) as a benchmark compound and 2,4,6‐trinitro‐1,3,5‐triazine (TNTA) as a theoretically new high performance energetic compound. It is shown that some of these compounds can be seen as interesting high‐nitrogen organic explosives with relatively low sensitivity which could be introduced for some important industrial applications. Since some of the new compounds have good oxygen balance, calculated specific impulses confirm that these compounds can be considered as suitable oxidizers in solid propellants.     

Quantum Chemical Studies on the Structure and Performance Properties of 1,3,4,5‐Tetranitropyrazole: A Stable New High Energy Density Molecule

Molecular orbital calculations were performed for the geometric and electronic structures, band gap, thermodynamic properties, density, detonation velocity, detonation pressure, stability and sensitivity of 1,3,4,5‐tetranitropyrazole ( R23 ). The calculated density (approx. 2060 kg m⁻³), detonation velocity (approx. 9.242 km s⁻¹) and detonation pressure (approx. 41.30 GPa) of the model compound are appearing to be promising compared to hexahydro‐1,3,5‐trinito‐1,3,5‐triazine (RDX) and octahydro‐1,3,5,7‐tetranitro‐l,3,5,7‐tetrazocine (HMX). Bader’s atoms‐in‐molecules (AIM) analysis was also performed to understand the nature of the intramolecular N ⋅⋅⋅ O interactions and the strength of trigger X NO₂ bonds (where XC, N) of the optimized structure computed from the B3LYP/aug‐cc‐pVDZ level.     

Estimations of Vapor Pressures by Thermogravimetric Analysis of the Insensitive Munitions IMX‐101, IMX‐104, and Individual Components

We have calculated the vapor pressures of the new explosives ordnances IMX‐101 and IMX‐104 and their respective components, 2,4‐dinitroanisole (DNAN), nitroguanidine (NQ), nitrotriazolone (NTO), and hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) by the method of rising temperature thermogravimetric analysis. Clausius‐Clapeyron relationships were assumed for each case and the vapor pressures were estimated from the Langmuir equation over an appropriate temperature range just below substance melting/decomposition points. For vapor pressures extrapolated to room temperature, the rank with respect to decreasing volatility was found to be: DNAN>IMX‐104>IMX‐101>NQ>RDX>NTO. Interestingly, vapor pressure depression is observed in IMX formulations, where the formulation has a lower vapor pressure than its most volatile component, DNAN. The enthalpy of sublimation was determined for each substance and formulation from Clausius‐Clapeyron equations generated by analysis of the thermogravimetric data. The general trends in vapor pressures and sublimation enthalpies associated with the component materials were in good agreement with previous experimental and computational results. The results obtained by this study have importance for future investigations of IMX, specifically for chemical detection and assessment of environmental fate.     

Preparation and Characterization of Hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine/Ammonium Perchlorate Intermolecular Explosives

Hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine/ammonium perchlorate/glycidyl azide polymer (RDX/AP/GAP) intermolecular explosives (IMX) with different proportions of RDX to AP were prepared by sol‐gel method, and the structure and performance was characterized by Brunauer‐Emmett‐Teller measurements (BET), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results showed that the specific surface area of RDX/AP/GAP IMX decreased with the addition of AP. The crystals of AP and RDX in RDX/AP/GAP intermolecular explosives were in the range of 20–48 nm and 23–55 nm, respectively. In addition, RDX/AP/GAP intermolecular explosives had the largest heat release at zero balance.     

Investigation on the Thermal Expansion and Theoretical Density of 1,3,5‐Trinitro‐1,3,5‐Triazacyclohexane

The CTE and the theoretical density are important properties for energetic materials. To obtain the CTE and the theoretical density of 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX), XRD, and Rietveld refinement are employed to estimate the dimensional changes, within the temperature range from 30 to 170 °C. The CTE of a, b, c axis and volume are obtained as 3.07×10⁻⁵ K⁻¹, 8.28×10⁻⁵ K⁻¹, 9.19×10⁻⁵ K⁻¹, and 20.7×10⁻⁵ K⁻¹, respectively. Calculated from the refined cell parameters, the theoretical density at the given temperature can be obtained. The theoretical density at 20 °C (1.7994 g cm⁻³) is in close match with the RDX single‐crystal density (1.7990 g cm⁻³) measured by density gradient method. It is suggested that the CTE measured by XRD could perfectly meet with the thermal expansion of RDX.     

Synthesis and Characterization of the Nitrogen‐Rich Hyperbranched Polymers – Poly([1,2,3]‐Triazole‐[1,3,5]‐Triazine)s

Novel hyperbranched poly([1,2,3]‐triazole‐[1,3,5]‐triazine)s (HBP TT) were synthesized by a 1,3‐dipolar cycloaddition reaction from AB₂ monomer – 2‐azido‐4,6‐bis‐prop‐2‐yn‐1‐yloxy‐ [1,3,5]‐triazine (ABPOT). The monomer contains one azide group A and two terminal alkyne units B. Thermal polymerization of ABPOT in bulk or in DMF solution leads to hyperbranched polymers containing both 1,4‐ and 1,5‐disubstituted [1,2,3]‐triazoles. The monomer was also polymerized catalytically in the presence of Cu(I) salts under mild reaction conditions in DMSO solution and in bulk affording hyperbranched poly‐[1,2,3]‐triazoles 1,4‐disubstituted only. The reactions lead to the products soluble in aprotic polar solvents like DMSO or DMF. Side reactions can proceed in a few cases, particularly: (i) homocoupling of alkyne groups, leading to the formation of insoluble products as a result of cross‐linking, (ii) isomerization of propynyloxytriazine fragments to propynyl‐ or propadienyltriazinone ones, and (iii) hydrolysis of triple bonds without the loss of solubility. Heats of formation of monomer and synthesized polymers were calculated from their combustion heats. All products were characterized by NMR‐, IR‐spectroscopy, and size exclusion chromatography (SEC) data. The obtained results open the prospect for the use of HBP TT as the high‐enthalpy modifiers for energetic and non‐energetic binders.     

Computed Thermodynamic and Explosive Properties of 1‐Azido‐2‐nitro‐2‐azapropane (ANAP)

Some thermodynamic and explosive properties of the recently reported 1‐azido‐2‐nitro‐2‐azapropane (ANAP) have been determined in a combined computational ab initio (MP2/aug‐cc‐pVDZ) and EXPLO5 (Becker–Kistiakowsky–Wilson's equation of state, BKW EOS) study. The enthalpy of formation of ANAP in the liquid phase was calculated to be Δ_fH°, ANAP(l)=+297.1 kJ mol⁻¹. The heat of detonation (Q_v), the detonation pressure (P), and the detonation velocity of ANAP were calculated to be Q_v=−6088 kJ kg⁻¹, P=23.8 GPa, D=8033 m s⁻¹. A mixture of ANAP and tetranitromethane (TNM) was investigated in an attempt to tailor the impact sensitivity of ANAP, but results obtained indicate that the mixture is almost as sensitive as pure ANAP. On the other hand, ANAP and TNM were found to be chemically compatible (¹H, ¹³C, ¹⁴N NMR; DSC) and a 1 : 1 mixture (by weight) of both components was calculated to have superior explosive properties than either of the individual components: Q_v=−6848 kJ kg⁻¹, P=27.0 GPa, D=8284 m s⁻¹.     

Assessment of aged biodegradable polymer‐coated nano‐zero‐valent iron for degradation of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX)

BACKGROUND: This study reports on the effects of aging on suspension behavior of biodegradable polymer‐coated nano‐zero‐valent iron (nZVI) and its degradation rates of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) under reductive conditions. The polymers investigated included guar gum, potato starch, alginic acid (AA), and carboxymethyl cellulose (CMC). Polymer coating was used to mitigate nZVI delivery hindrance for in situ treatment of RDX‐contaminated groundwater. RESULTS: The RDX degradation rates by bare nZVI and starch‐coated nZVI suspensions were least affected by aging although these suspensions exhibited the least favorable dispersion behavior. CMC, AA, and guar gum coating improved nZVI rates of degradation of RDX but these rates decreased upon aging. The best suspension stability upon aging was achieved by CMC and AA. Guar gum with loadings rates one order of magnitude lower than that of CMC and AA achieved good iron stabilization but significantly higher RDX degradation rates. CONCLUSION: It is demonstrated that both migration and reactivity of polymer‐stabilized nZVI should be explicitly evaluated over a long period before application in the field. Guar gum coated nZVI appeared best suited for in situ application because it maintained good suspension stability, with RDX degradation rates least affected by aging compared with the other polymers tested. © 2012 Society of Chemical Industry     

Polyimides containing s‐triazine rings

A series of new polyimides containing s‐triazine rings have been synthesized via Diels–Alder intermolecular polymerization of 2,6‐bis(2‐furanylmethylimino)‐4‐isopropoxy‐1,3,5‐triazine with various bis(maleimide)s. All the poly(imino‐s‐triazine imide)s were characterized by elemental analyses, FTIR spectral studies, number average molecular weight ( M _n) by non‐aqueous conductometric titration and thermogravimetry. Glass‐fibre reinforced composites were prepared via an in situ Diels–Alder intermolecular reaction between 2,6‐bis(2‐furanylmethylimino)‐4‐isopropoxy‐1,3,5‐triazine and various bis(maleimide)s. The composites were characterized for chemical resistivity and mechanical properties. © 2003 Society of Chemical Industry     

Degradation of hexahydro‐1,3,5‐trinitro‐1,3, 5‐triazine (RDX) by anaerobic mesophilic granular sludge from a UASB reactor

BACKGROUND: This study investigated the performance of anaerobic mesophilic granular sludge for the degradation of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX). Batch tests were conducted to investigate the effects of different supplements on the RDX degradation ability of anaerobic granular sludge, as well as the contributions of both physicochemical and biological processes involved in RDX removal from aqueous solution. RESULTS: Anaerobic granular sludge exhibited good performance in treating RDX as the sole substrate. Biodegradation was the main mechanism responsible for RDX removal. Ammonium had no significant promoting effect on the degradation process. The presence of glucose was found to enhance the degradation of RDX by anaerobic granular sludge, while the addition of sulfate and nitrate had adverse effects on the reductive transformation of RDX. CONCLUSIONS: Anaerobic granular sludge is capable of removing RDX from aqueous solution with high efficiency. This study showed good prospects for high‐rate anaerobic processes in the treatment of munition wastewater. The results can be used for the design and optimization of high rate anaerobic systems for the elimination of RDX. Copyright © 2010 Society of Chemical Industry     

Simultaneous degradation of nitroaromatic compounds TNT,RDX, atrazine,and simazine by Pseudomonas putida HK‐6 in bench‐scale bioreactors

BACKGROUND: Environmental contamination by nitroaromatic compounds such as 2,4,6‐trinitrotoluene (TNT), hexahydro‐1,3,5‐trinitro‐1,3,5‐s‐triazine (RDX), atrazine, and/or simazine (TRAS) generated as waste from military and agricultural activities is a serious worldwide problem. Microbiological treatment of these compounds is an attractive method because many explosives and herbicides are biodegradable and the process can be made cost‐effective. We explored the feasibility of using cultures of Pseudomonas putida HK‐6 for simultaneous degradation of TRAS with the aim of microbial application in wastewater treatment in bench‐scale bioreactors. RESULTS: Experiments were conducted to study the effects of supplemental carbons, nitrogens, and Tween‐80 on the degradation of Ps. putida HK‐6 in media containing TRAS as target substrate(s). The most effective TRAS degradation was shown in the presence of molasses. Addition of nitrogen sources produced a delayed effect for the target substrate(s). Tween‐80 enhanced the degradation of target substrate(s). Simultaneous degradation of these compounds proceeded to completion within the given period. CONCLUSIONS: Ps. putida HK‐6 was capable of growth with TRAS, and the effects of supplements on TRAS degradation and simultaneous TRAS degradation were evaluated in bench‐scale bioreactors. The results of this study have practical applications in the processes of industrial waste stream treatment where the disposal of TRAS may be problematic. Copyright © 2008 Society of Chemical Industry     

Application of reactive solvents of melamine for synthesis of polyetherols with perhydro‐1,3,5‐triazine rings

The application of reactive solvents (RSs), namely hydroxymethyl derivatives of acetone for digestion of isocyanuric acid, which is insoluble in most organic solvents except for DMSO, makes the substrate available for further conversions. At this step, the incorporation of perhydro‐1,3,5‐triazine ring into RS takes place. The obtained solutions were used for synthesis of polyetherols containing perhydro‐1,3,5‐triazine rings in reaction with oxiranes: ethylene and propylene oxides. The polyetherols were then used to obtain foamed polyurethanes with enhanced thermal stability. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Characterization of 4,6‐Diazido‐N‐nitro‐1,3,5‐triazine‐2‐amine

4,6‐Diazido‐N‐nitro‐1,3,5‐triazine‐2‐amine (DANT) was prepared with a 35 % yield from cyanuric chloride in a three step process. DANT was characterized by IR and NMR spectroscopy (¹H, ¹³C, ¹⁵N), single‐crystal X‐ray diffraction, and DTA. The crystal density of DANT is 1.849 g cm⁻³. The cyclization of one azido group and one nitrogen atom of the triazine group giving tetrazole was observed for DANT in a dimethyl sulfoxide solution using NMR spectroscopy. An equilibrium exists between the original DANT molecule and its cyclic form at a ratio of 7 : 3. The sensitivity of DANT to impact is between that for PETN and RDX, sensitivity to friction is between that for lead azide and PETN, and sensitivity to electric discharge is about the same as for PETN. DANT′s heat of combustion is 2060 kJ mol⁻¹.     

Degradation of TNT,RDX, and HMX Explosive Wastewaters Using Zero‐Valent Iron Nanoparticles

The high‐energy explosives 2,4,6‐trinitrotoluene (TNT), hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX), and the high melting explosive octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) are common groundwater contaminants at active and abandoned munitions production facilities causing serious environmental problems. A highly efficient and environmentally friendly method was developed for the treatment of the explosives‐contaminated wastewaters using zero‐valent iron nanoparticles (ZVINs). ZVINs with diameters of 20–50 nm and specific surface areas of 42.56 m² g⁻¹ were synthesized by the co‐precipitation method. The explosives degradation reaction is expressed to be of pseudo first‐order and the kinetic reaction parameters are calculated based on different initial concentrations of TNT, RDX, and HMX. In addition, by comparison of the field emission scanning electron microscopy (FE‐SEM) images for the fresh and reacted ZVINs, it was apparent that the ZVINs were oxidized and aggregated to form Fe₃O₄ nanoparticles as a result of the chemical reaction. The X‐ray diffraction (XRD) and X‐ray absorption near edge structure (XANES) measurements confirmed that the ZVINs corrosion primarily occurred due to the formation of Fe₃O₄. Furthermore, the postulated reaction kinetics in different concentrations of TNT, RDX, and HMX, showed that the rate of TNT removal was higher than RDX and HMX. Furthermore, by‐products obtained after degradation of TNT (long‐chain alkanes/methylamine) and RDX/HMX (formaldehyde/methanol/hydrazine/dimethyl hydrazine) were determined by LC/MS/MS, respectively. The high reaction rate and significant removal efficiencies suggest that ZVINs might be suitable and powerful materials for an in‐situ degradation of explosive polluted wastewaters.     

Amine Modifiers with an s‐Triazine Ring for Unsaturated Polyester Resins, 1

Summary: Synthesis and properties of amine modifiers for unsaturated polyester resins are presented. The modifiers were obtained by reacting 3‐azapentan‐1,5‐diol (diethanoloamine) with 2,4‐dichloro‐6‐methoxy‐1,3,5‐triazine, 2‐chloro‐4,6‐dimethoxy‐1,3,5‐triazine or with cyanuric chloride. They were incorporated into the structure of typical unsaturated polyester resins in the polycondensation stage, i.e. prior to dilution with styrene, in the amount of 0.25 through to 2.0 wt.‐%. The effect of the modifier presence on the curing behavior of the resulting resins is discussed.

Gelation times for unsaturated polyester resins modified with modifiers A , B , and C are shown with the curing system consisting of peroxide initiator and (?): 0.10 cm³, (?): 0.15 cm³, (?): 0.25 cm³, and (?): 0.50 cm³ of cobalt(II ) octenate solution per 25 g of resin.     

β‐Cyclodextrin inclusive interaction driven separation of organic compounds

A novel selective separation method for organic compounds, especially thermosensitive substances, has been proposed using unsubstituted β‐cyclodextrin (β‐CD) as a host and some alcohols and aldehydes as model guests in aqueous solution. The separation factors were evaluated from the extraction of an equimolar mixture of alcohol and aldehyde compounds. The inclusion equilibrium constants for several alcohols and aldehydes over β‐CD have been calculated through their UV‐vis spectra. The Gibbs free energy changes of β‐CD/substrates complexes (ΔG) have been calculated combined B3LYP/6‐31G(d)//ONIOM2(B3LYP/6‐31G(d):PM3) with semicontinuum solvation model. The difference of Gibbs free energy changes (ΔΔG) for the inclusion complexes formed via the intermolecular weak interactions e.g., hydrogen bond and electrostatic interaction was the reason why alcohol and aldehyde compounds could be selectively separated. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Synthesis and applications of oligoetherols with perhydro‐1,3,5‐triazine ring and boron

A new method of preparation of oligoetherols containing perhydro‐1,3,5‐triazine rings and boron atoms is presented. The oligoetherols were obtained in the reaction of 1,3,5‐tris(2‐hydroxyethyl) isocyanurate with boric acid followed by reaction with alkylene carbonates. The structure and physical properties of the products render them good candidate for preparing the polyurethane foams. The foams were obtained and their properties were compared with those synthesized from isocyanuric acid and alkylene carbonates. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

A DFT Study on the Structures and Energies of Isomers of 4‐Amino‐1,3‐dinitro‐1,2,4‐triazol‐5‐one‐2‐oxide: New High Energy Density Compounds

Isomers of 4‐amino‐1,3‐dinitrotriazol‐5‐one‐2‐oxide (ADNTONO) are of interest in the contest of insensitive explosives and were found to have true local energy minima at the DFT‐B3LYP/aug‐cc‐pVDZ level. The optimized structures, vibrational frequencies and thermodynamic values for triazol‐5‐one N‐oxides were obtained in their ground state. Kamlet‐Jacob equations were used to evaluate the performance properties. The detonation properties of ADNTONO (D=10.15 to 10.46 km s⁻¹, P=50.86 to 54.25 GPa) are higher compared with those of 1,1‐diamino‐2,2‐dinitroethylene (D=8.87 km s⁻¹, P=32.75 GPa), 5‐nitro‐1,2,4‐triazol‐3‐one (D=8.56 km s⁻¹, P=31.12 GPa), 1,2,4,5‐tetrazine‐3,6‐diamine‐1,4‐dioxide (D=8.78 km s⁻¹, P=31.0 GPa), 1‐amino‐3,4,5‐trinitropyrazole (D=9.31 km s⁻¹, P=40.13 GPa), 4,4′‐dinitro‐3,3′‐bifurazan (D=8.80 km s⁻¹, P=35.60 GPa) and 3,4‐bis(3‐nitrofurazan‐4‐yl)furoxan (D=9.25 km s⁻¹, P=39.54 GPa). The  NH₂ group(s) appears to be particularly promising area for investigation since it may lead to two desirable consequences of higher stability (insensitivity), higher density, and thus detonation velocity and pressure.