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Compositions based on 2,4-dinitroanisole (DNAN) with several cyclic nitramines, namely 1,3,5-trinitro-1,3,5-triazinane (RDX) and β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane (β-HMX), cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole (BCHMX), and ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (ε-CL20) were prepared and studied in comparison with 2,4,6-trinitrotoluene (TNT) compositions. Impact and friction sensitivities, combustion heats, detonation velocities and relative explosive strengths (RS) were determined for these mixtures. Detonation parameters were calculated by means of the Explo5 thermodynamic code. The difference between the TNT and DNAN compositions was shown by the relationships between RS and the energy outputs of the prepared mixtures. The results show better sensitivity characteristics for DNAN composition in comparison with same compositions containing TNT. [ABSTRACT FROM AUTHOR]

A new focus in the fields of energetic materials is on preserving high performance while enhancing manipulation safety. In this work, a special type of plastic‐bonded explosive (PBX) mixture has begun to be developed by combining a new nitramine, cis‐1,3,4,6‐tetranitrooctahydroimidazo‐[4,5‐d]imidazole (BCHMX), with the thermally stable explosives 1,3‐diamino‐2,4,6‐trinitrobenzene (DATB) and 2,2',4,4',6,6'‐hexanitroazobenzene (HNAB) bonded by a styrene‐butadiene rubber (SBR) binder. The studied PBXs prepared are insensitive explosives. They have been compared with Czech plastic explosives (SEMTEX 10 and SEMTEX 1H), a new Egyptian plastic explosive (EPX‐1), a Swedish plastic explosive (Sprängdeg m/46) and with analogous PBXs, filled by 1,3,5‐trinitro‐1,3,5‐triazinane (RDX), β‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane (β‐HMX), and cis‐1,3,4,6‐tetranitrooctahydroimidazo‐[4,5‐d]imidazole (BCHMX). The individual explosives, PETN, BCHMX, β‐HMX and RDX, have been studied as well. Thermal behavior of the pure active components has been investigated. The impact and friction sensitivities have been obtained along with the measured detonation velocities. The detonation characteristics have also been calculated using the EXPLO5 code. The relationship between performance and sensitivity to mechanical impulses has been investigated. The results have shown that DATB has a significant influence on the reduction of the sensitivity of BCHMX to a level close to TNT and much lower than all the other studied plastic explosives. In addition, the new PBX based on BCHMX and DATB has higher detonation characteristics than the commercial PBXs and TNT. The influence of DATB on BCHMX is a promising topic requiring more research for its application. [ABSTRACT FROM AUTHOR]

Electric spark energy, EES, for a 50% probability of initiation of the 14 nitramines was determined using a measuring instrument in which the electrodes are in direct contact with the sample. Indirectly proportional relationships were established between the logarithm of the EES values and the length of the longest N-N bond in the nitramine molecule. This finding is compatible with the mechanism of the first step in the electro-reduction of the nitramine grouping. Directly proportional relationships were found to exist between the EES values and the crystal lattice free volumes, ΔV (i.e. an increase in the ΔV values increases the nitramine's resistance to electric sparks) but there were several nitramines with the opposite course of this relationship. Also a semilogarithic relationships between the EES values and a ratio of intrinsic volumes of molecule, Vint, to the ΔV values were described as well as ambiguous linear dependence between these energies and a sum of the positive and negative extremes of the molecular surface electrostatic potentials, VS,Σ. Several nitramines studied (always the same ones) display roughly the same distribution in the coordinate systems of relationships with lengths of the longest N-N bonds, the Vint/ΔV ratio and the sum VS,Σ as the independent variables. It was found that, typically, such relationships start from a single identical point, in effect a point corresponding to data for a structural unit from which the studied nitramines can be hypothetically generated, and/or are converging on another point, often the one corresponding to the data for HNIW. All the findings point to a fundamental influence of the intermolecular forces on reactivity of nitramines exposed to electric sparks. [ABSTRACT FROM AUTHOR]

Crystal lattice free volumes, ΔV, of 22 nitramines introduced into relationships of maximal theoretical crystal densities (TMD), detonation velocities (D) and volume heats of explosives (r.Q). Values of all these characteristics increase with an increase in the ΔV values. However, more realistic dependencies for the TMD and D values are obtained by using correlations with ratio of the intrinsic molecular volume, Vint, to ΔV (i.e. Vint/ΔV), whereby the dependence on the D values reflects their similar relationship to a sum of the positive (VS,max) and negative (VS,min) extremes of the molecular surface electrostatic potentials (VS,∑). Also, directly proportional linear relationships are specified between the VS,∑ values on the one hand, and the ΔV and Vint/ΔV values, on the other. It is stated that the crystal lattice free volumes might have a similar role in detonation of nitramines as the intermolecular force effect in their molecular crystals (they are as if representative of such forces). [ABSTRACT FROM AUTHOR]

Information about the forty nine nitraminic plastic bonded explosives (PBXs) and different nitramines were collected. Fillers of these PBXs are nitramines 1,3,5-trinitro-1,3,5-triazinane (RDX) and b-1,3,5,7-tetranitro-1,3,5-tetrazocane (b-HMX), cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole (bicyclo-HMX, BCHMX) and ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (ε-HNIW, CL-20) which are bonded by polyfluoro-elastomers, polydimethyl-siloxane, poly-glycidyl azide, polyisobutylene, polystyrene-butadiene, poly-acrylonitrile-butadiene and hydroxyl-terminated polybutadiene in addition to a melt cast compositions based on 2,4,6-trinitrotoluene. For thirty two of these PBXs the relationships are specified and analyzed between heats of their combustion and relative explosive strengths; by means of these relationships it might be possible to estimate, which groupings in the macromolecule of binder could be liable to their primary fission in the PBXs initiation. Similarly, for forty two of these explosives, the relationships are described and analyzed between their enthalpies of formation and impact sensitivities; here is especially attention paid to PBXs filled by BCHMX. Specific rate constants from Vacuum Stability Test (VST) of four nitramines and twenty PBXs are introduced into relationships with their enthalpies of formation. Regarding to all the mentioned cases, increasing of energy content of the studied explosives leads to increase of the relative explosive strength or initiation reactivity, respectively. Exception with the opposite trend, the outputs of VST are for BCHMX, where in PBXs are matrices with the esteric plasticizers or the energetic poly-glycidyl azide. Admixture of RDX or HMX, respectively, into the BCHX PBXs gives ternary PBXs whose thermal stability, in the sense of applied VST, is higher comparing to the original binary explosives. [ABSTRACT FROM AUTHOR]

The linear, directly proportional, equations between the Arrhenius parameters (Ea and log A) of the thermal decomposition and the crystal lattice free space per molecule, ΔV, of 22 nitramines are described. It is shown that, because of a significant limitation by the molecular structural characteristics of such compounds, they are divided into a number of partial relationships. These partial relationships divide the nitramines into a group of substances relating to dimethyl nitramine and a sub-group related to ε-HNIW. These directly proportional equations mean that an increase in the ΔV values is related to an increase in the thermal stability of the corresponding nitramines. A comparison with similar published dependencies for the impact and friction sensitivities, on the one hand, and with the relationship between the Ea values and the sum of the negative and positive extremes of molecular surface electrostatic potentials, on the other, confirms the well-known fact that intermolecular interaction in the nitramines studied plays a decisive role in the thermal reactivity of such compounds. The crystal lattice free space manifests itself here perhaps only in the solid state thermal decomposition of RDX, HMX and DINGU. This study again confirms a level of disorder in the distribution of the forces in the crystal lattice of the "common" quality of ε-HNIW, compared with its "reduced sensitivity (RS)" or pure analogues. [ABSTRACT FROM AUTHOR]

The thermal behavior and decomposition kinetics of a melt cast composition based on mixture of bicyclic nitramine, cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5- d ]imidazole (BCHMX) and insensitive explosive, 2,4,6-trinitrotoluene (TNT) (60/40 by wt %) have been investigated. This behavior was studied by non-isothermal TG and DSC techniques and the decomposition kinetics were determined by the isoconversional methods named Kissinger and modified Kissinger-Akahira-Sunose (KAS). For comparison, the traditional TNT casted compositions based on 1,3,5-trinitro-1,3,5-triazinane (RDX) named composition B and β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane (β-HMX) were studied. Also Vacuum Stability Test (VST) was used isothermally at 120 °C for six hours to determine the specific rate constants. Despite of the volatility of TNT, the obtained results showed that the reactivity of the studied cyclic nitramines in mixtures was increased in the order HMX < BCHMX < RDX, because of their incorporation into the melted TNT (acidic solvent). The kinetic compensation effect and outputs of the Vacuum Stability Test clearly exemplify this reactivity. Nevertheless, taking into consideration the recently published facts about this composition and its application in practice, the mixture is a promising composition which has high relative explosive strength compared with the other studied compositions. [ABSTRACT FROM AUTHOR]

Abstract: In this work, preparation and characterization of a plastic bonded explosive (PBX) based on a mixture of cis‐1,3,4,6‐tetranitrooctahydroimidazo‐[4,5‐d]imidazole (BCHMX) and 1,1‐diamino‐2,2‐dinitroethene (DADNE or FOX‐7) bonded by poly‐dimethyl siloxane binder (PDMS) were investigated. Impact and friction sensitivities were determined. Detonation velocity was measured and the detonation characteristics were determined by the EXPLO 5 thermodynamic code. Relative explosive strength was determined using the ballistic mortar test. For comparison, four individual cyclic nitramines, RDX (1,3,5‐trinitro‐1,3,5‐triazinane), β‐HMX (β‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane), BCHMX and ϵ‐CL20 (ϵ‐2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane, ϵ‐HNIW) in addition to their PBXs bonded by the same polymeric matrix were studied. Also traditional plastic explosives such as Czech plastic explosive (SEMTEX 10) and Egyptian Plastic Explosive (EPX‐1) were included in the study. The results confirmed that BCHMX/FOX7‐Sil has the lowest impact and friction sensitivity of all the studied samples and its detonation velocity and pressure are higher than the traditional PETN plastic explosives. [ABSTRACT FROM AUTHOR]

The relationship between friction sensitivity (FS) and the crystal lattice free space per molecule, DV, of thirteen nitramines is described by a linear equation, divided into a number of the partial relationships with strong limitations by their molecular structure characteristics. Increasing FS due to raising of the DV values is not clearly confirmed. The influence of the DV values on friction sensitivity of nitramines is similar to that of their aza atoms which influence the mutual orientations of nitro groups in neighboring molecules. The dipole-dipole interaction of the oxygen and nitrogen atoms of nitro groups in neighboring nitramine molecules has a major effect on their own FS. In accordance with this interaction, a directly proportional relationship was derived between FS and the intrinsic gas phase molecular volume, Vint, of the nitramines mentioned, which is divided also into several straight lines according to relatively tight molecular structure similarity. The relationships found again confirm a level of disorder in the distribution of the forces in the crystal lattice of the "common" quality of ε-2,4,6,8,10,12-hexanitro- 2,4,6,8,10,12-hexaazaisowurtzitane, in comparison with its reduced sensitivity (RS) or chemically pure analogue. [ABSTRACT FROM AUTHOR]

More detailed analysis of a mutual relationship of impact sensitivity (detected by sound) and crystal lattice free volume, DV, for the 18 nitramines shows that its course is not unequivocal. For a part of the studied compounds this sensitivity has increased with increase of the DV values, but for fairly big number of nitramines the relationship works in the opposite direction, especially for data of 1,3,5-trinitro-1,3,5- triazinane, 1,3,5,7-tetranitro-1,3,5,7-tetrazocane, and β- and ε-polymorphs of 2,4,6,8,10,12-hexanitro- 2,4,6,8,10,12-hexaazaisowurtzitane. Initiation reactivity of technical ε-polymorph of 2,4,6,8,10,12- hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane gives the impression by disorderliness in distribution of the actions of forces in its crystal lattice in comparison with its RS (reduced sensitivity) or chemically pure analogue. Limitations of partial shapes of the mentioned relationship by the molecular-structural similarity, and already published information about the decisive factors governing the crystal structure, signalizes a higher influence of the intermolecular interactions in a crystal lattice in comparison with influence of the crystal lattice free volume for initiation of the crystalline EMs. [ABSTRACT FROM AUTHOR]

In this work, glycidyl azide polymer (GAP) has been prepared and studied. In addition, a series of different plastic bonded explosive (PBXs) based on GAP were prepared using five cyclic nitramines, namely. 1,3,5-trinitro-1,3,5-triazinane (RDX) and β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane (β-HMX), cis -1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole (BCHMX), RS-ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (RS-ε-CL-20) and 4,10-dinitro-2,6,8,12-tetraoxa-4,10-diazaisowurtzitane (TEX). The thermal behavior and decomposition kinetics have been investigated by means of the nonisothermal TG and DSC techniques and the decomposition kinetics were obtained by the isoconversional methods (Kissinger and modified Kissinger-Akahira-Sunose (KAS) methods). It was indicated that GAP has a significant effect on the activation energy distribution for the thermal decomposition of cyclic nitramines and it motivates the initial autocatalysis effect of RDX and CL-20. The mean activation energies of the thermal decomposition were reduced comparing with the individual nitramines, and their values are 187.7, 191.6, 110.7, 118.5, 283.8, 146.1, and 171.6 kJ mol −1 for BCHMX/GAP, CL-20/GAP, RDX/GAP, HMX/GAP peak 1, HMX/GAP peak 2, TEX/GAP and GAP respectively. The GAP admixture changes an inversely proportional linear relationship between the mentioned energies and longest lengths of the N N bonds in nitramine molecules into a directly proportional one for the nitramines in the GAP-PBXs due to the possibility of the GAP complex formation with the studied nitramines. The results show that BCHMX/GAP has a good thermal stability reached the same level of TEX/GAP while the thermal stability of RDX/GAP considered the lowest value of all the studied PBXs. [ABSTRACT FROM AUTHOR]

The zero-order reaction rates (specific rate constants) of isothermal decomposition at 120 °C of plastic bonded explosives (PBXs) in the first six hours of decomposition were measured by means of the Czech vacuum stability test, STABIL. The PBXs were filled by RDX (1,3,5-trinitro-1,3,5-triazinane), β−HMX (β−1,3,5,7-tetranitro-1,3,5,7-tetrazocane), BCHMX and ϵ-CL20 (ϵ-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, ϵ-HNIW) and, in one case, on a mixture of BCHMX and 3-nitro-1,2,4-triazol-5-one (NTO), in a 1:1 wt. ratio. These nitramines were bonded by 9% by wt. of softened polyisobutylene matrix, 13% by wt. of softened polystyrene-butadiene matrix, 18% by wt. of crosslinked hydroxyl-terminated polybutadiene, 12% by wt. of polydimethylsiloxane and by 40% of TNT. The relationships of specific rate constants with experimental detonation velocities, impact and friction sensitivities of these PBXs are shown and discussed. It is postulated that this approach provides results which are applicable to studies of initiation reactivity of energetic materials and which are fully comparable with those of other methods of investigation in this area. [ABSTRACT FROM AUTHOR]

At present, cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole (bicyclo-HMX, BCHMX) and ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (ε-HNIW, CL-20) are a topic of interest from the attractive and the potentially attainable nitramines. They were chosen to be studied in comparison with 1,3,5-trinitro-1,3,5-triazinane (RDX) and β-1,3,5,7-tetranitro-1,3,5-tetrazocane (β-HMX). Marginal attention is devoted also to 4,8,10,12-tetranitro-2,6-dioxa-tetraazawurtzitane (Aurora 5). BCHMX, ε-HNIW, RDX, and HMX were studied as plastic bonded explosives (PBXs) with elastic properties based on Composition C4 and Semtex 10 matrices. Also they were studied as a highly pressed PBXs based on the Viton A binder. The detonation parameters and sensitivity aspects of these nitramines and their corresponding PBXs were determined. Relative explosive strengths (RS) of these compositions are mentioned with mutual relationships between the measured RS values and some detonation parameters. These relationships indicate a possibility of changes in detonation chemistry of these mixtures filled mainly by HNIW. A sensitivity of RS-CL20 (HNIW with reduced sensitivity) is reported and the new findings in the friction sensitivity are discussed. [ABSTRACT FROM AUTHOR]

A series of plastic bonded explosives (PBXs) based on Viton A and Fluorel binders were prepared using four nitramines, namely RDX (1,3,5-trinitro-1,3,5-triazinane), β-HMX (β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane), BCHMX ( cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole), and ε-HNIW (ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane). The detonation velocities, D, were determined. Detonation parameters were also calculated by means of modified Kamlet & Jacobs method, CHEETAH and EXPLO5 codes. In accordance with our expectations BCHMX based PBXs performed better than RDX based ones. The Urizar coefficient for Fuorel binder was also calculated. [ABSTRACT FROM AUTHOR]

Matrices based on polyisobutylene (PIB), polymethyl-methacrylate (PA), Viton A 200, Dyneon FT 2481 (Fluorel), and polydimethyl-siloxane binders were studied as desensitizers. A series of plastic explosives (PBXs) were prepared, based on four different nitramines, namely RDX (1,3,5-trinitro-1,3,5-triazinane), β-HMX (β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane), BCHMX ( cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5- d]imidazole) and ε-HNIW (ε-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, ε-CL-20), bonded by the matrices mentioned. For comparison, pentaerythritol tetranitrate and certain commercial explosives based on it, Semtex 1A, Semtex 10 and Sprängdeg m/46, were used. Detonation velocities, sensitivities to impact and friction, and peak temperatures of thermal decomposition by differential thermal analysis technique (DTA) for all the explosives studied were determined. Heat of detonation was calculated by means of a thermodynamic calculation program (EXPLO 5 code). Fluoroelastomers have a neutral to positive effect on the thermal stability of nitramines and they have a significant effect on decreasing the friction sensitivity. However, their anti-impact efficiency is the lowest in this study although they have a positive effect on performance of the corresponding PBXs. PA and PIB matrices markedly decrease thermal stability of nitramines, the anti-impact influences of PIB-binders are better than those of PA-binders, while PA-binders have a higher anti-friction effect and slightly less negative influence on the performance of the PBXs in comparison with PIB mixtures. The polydimethyl-siloxane matrix has a neutral effect on thermal stability of the nitramines studied, it has an influence on the volume thermochemistry of detonation comparable with that of fluoroelastomers although it does not provide comparable performance, and its corresponding PBXs have optimum sensitivity parameters. [ABSTRACT FROM AUTHOR]

Four highly brisant nitramines, RDX (1,3,5-trinitro-1,3,5-triazinane), HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane), BCHMX (cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole), and ϵ-HNIW (ϵ-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane), were studied as extruded plastic explosives bonded by two plastic matrices based on polyisobutylene (C4 matrix) and poly-methylmethacrylate (plasticized by dioctyl-adipate) binders. The detonation velocities, D, were measured experimentally. Detonation parameters were also calculated by means of the Kamlet and Jacobs method and CHEETAH and EXPLO5 codes. These detonation parameters showed that plastic-bonded explosives (PBXs) based on BCHMX are more powerful explosives than those based on RDX. The Urizar coefficient for poly(methyl methacrylate) binder was also calculated. [ABSTRACT FROM PUBLISHER]

In a sample of 22 nitramines, the simplest features of surface electrostatic potentials (SEPs), their positive ( VS,max) and negative ( VS,min) extremes, are related to their detonation velocities, D, at maximal theoretical densities. The relationships between the VS,min and D values logically show the nitramino group as responsible for detonation initiation for these compounds. On the other hand, the VS,max values gave complicated relationships. As a criterion of the imbalance between the VS,max and VS,min extremes their sum was derived and used as a new simple characteristic of SEPs, VS,Σ. The VS,Σ values have close relationships with the D values and the corresponding relationships uniquely determine the nitramino grouping as a reactivity center for detonation of nitramines. This new criterion is shown to be the best SEP characteristic for the study of detonation initiation. In all the relationships mentioned in this study of nitramines, the increase in potentials and/or their sum correspond with an increase in the D values (energy content of molecules). [ABSTRACT FROM AUTHOR]

Abstract: On the basis of measurements of 18 high explosives by means of the Czech Vacuum Stability Test (VST) STABIL, a relationship has been specified between the results of this test and those of Russian manometric method. The said relationship was used to predict the Arrhenius parameters (E a and log A values) of four plastic explosives based on RDX and one high explosive based on PETN (Semtex). The slopes E a R −1 of Kissinger''s equation were specified by means of non-isothermal differential thermal analysis (DTA) and evaluation of the measurement results by means of the Kissinger method. The role played by binders and plasticizers in thermal decomposition of nitramines was pointed out on the basis of relationship between the E a values obtained from VST and the E a R −1 values obtained from DTA, both for plastic explosives, eight nitramines, Composition B and PETN. The relationships between the E a R −1 values and thermostability threshold was specified for the given group of explosives. The relationship classify some of the studied plastic explosives as belonging to nitramines with steric hindrance in the molecule (CPX, TNAZ and HNIW). The relationship between E a R −1 values and drop energies, E dr, sharply differentiates between plastic explosives and individual nitramines. From the relationship between the E dr and D 2 values it was found that the increasing performance of the studied nitramines and plastic explosives is connected with the decrease in their impact sensitivity. Also specified are the approximate linear dependences between the peak temperatures of exothermic decomposition of all the explosives studied and their ignition temperatures, T ig, or critical temperatures, T c; these dependences were applied to prediction of T ig and T c of both the studied plastic explosives and some of the nitramines. [Copyright &y& Elsevier]

Abstract: A brief survey is presented of the author''s results obtained from studies of the chemical micro-mechanisms of nitramines initiation from the point of view of organic chemistry. The relationships have been presented and discussed between the characteristics of impact and electric spark sensitivities, detonation and thermal decomposition, on the one hand, and 15N NMR chemical shifts of nitrogen atoms of nitramino groups, on the other. In the case of the impact sensitivity, the said relationships involve the 15N shifts of the amino nitrogen atoms carrying the nitro group primarily split off from the molecule. In the case of the initiation by shock, heat and electric spark, the 15N shifts of nitrogen atoms in the primarily split off nitro groups themselves are involved. Also, the relationships are presented between the characteristics of thermal reactivity and values of the electronic charges at the nitro groups that are primarily split off. It has been stated that the chemical micro-mechanisms of primary fission processes of molecules of nitramines in the initiation by mechanical stimuli (inclusive the detonation course) and electric spark should be the same as in the case of their low-temperature thermal decomposition. It has been found that the electron structure and close neighbourhood of nitrogen atom of the primarily leaving nitro group is a dominant factor in initiation by shock, electric spark and heat. In the case of initiation by impact a key role plays characteristics of amino nitrogen atoms which are carriers of these most reactive nitro groups. Also mentioned is relevance of the modified Evans–Polanyi–Semenov relationship. On the basis of the findings presented it also has been stated that the detonation transformation itself of the nitramines should be preceded by an induction period. [Copyright &y& Elsevier]

• Overheating in nitramines CACs with DATB &TATB increased thermal sensitivity. • The bonding ‒N‒O···H‒N= in CACs evident by E a vs asym- N-O stretching correlation. • van der Waals forces in CACs evident by E a vs asym- NO 2 stretching correlation. • Heats of combustion as a CACs energy content in linear relation to the ln E a values. The thermolysis of the co-agglomerates (CACs) of the attractive nitramines RDX, BCHMX, HMX and CL-20 with 1,3-diamino-2,4,6-trinitrobenzene (DATB) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) was studied by means of differential thermal analysis (DTA) and differential scanning calorimetry (DSC), using the Kissinger method for output evaluation. The insertion of both DATB and TATB molecules into nitramine crystal lattices markedly increased the thermal sensitivity of the resulting CACs to overheating. Depression in melting points was detected in all CACs and, with the exception of RDX CACs, also in the exothermic peaks. The RDX CACs differ from the other studied CACs by their decomposition in the liquid state. The activation energies (E a) , obtained correlate with asymmetric N-O stretching vibrations, confirming the important influence of ‒N‒O····H‒H= interactions in CACs; a similar correlation with asymmetric NO 2 stretching confirms the interactions of DATB and TATB molecules with nitramine molecules through van der Waals forces. The insertion of DATB or TATB into the crystal lattice of HMX or CL20 changes their polymorphic modification from β- to δ- and in the latter case from ɛ- to β- modifications in the corresponding CACs. The correlations of the E a values with the square of detonation velocity as a representative of performance and with the heat of combustion as a representative of the energy content are consistent with already previously described relationships of this type, including exceptions for pure nitramines. [Display omitted] [ABSTRACT FROM AUTHOR]

A new plastic bonded explosive mixture (PBX) based on cis -1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole (BCHMX) and 3-nitro-1,2,4-triazol-5-one (NTO), bonded by polydimethylsiloxane (PDMS) binder (44/44/12 wt.%), was prepared and studied as an explosive for the Low Vulnerable Ammunition (LOVA) in comparison with the LOVA casted composition NTO/TNT (50/50 wt%) and with analogous PBXs, filled by RDX (1,3,5-trinitro-1,3,5-triazinane), β–HMX (β–1,3,5,7-tetranitro-1,3,5,7-tetrazocane), BCHMX and ϵ-CL20 (ϵ-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane, ϵ-HNIW). The mentioned PBX with the pure NTO and BCHMX, have been investigated with regard to their thermal behavior and decomposition kinetics (Kissinger and modified Kissinger-Akahira-Sunose (KAS methods) by means of the Differential Scanning Calorimetry (DSC) and Thermogravimetry (TG) techniques. Impact and friction sensitivities in addition to the measured detonation velocities and the calculated detonation characteristics (EXPLO5 code) were determined. Results of the thermo-analytical study show certain instability of PDMS binder in presence of NTO over 170 °C and decomposition of NTO as a solution in degradation products of this binder in temperature region typical for thermal decomposition of BCHMX. Nevertheless, the PDMS matrix shows to be a good binder for a LOVA explosive, filled by BCHMX and NTO, due to its markedly positive effect on increasing of the resistance of this PBX against mechanical stimuli and a good thermal stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • CACs with linear stirrer(B1) & cross stirrer(B2); B2- yielding novel properties. • BTATz stabilized HMX in the CACs as its α-polymorph & lowest sensitivity (46 J) • α-HMX/BTATz detonation energy (6097 J·g−1) higher to pure β-HMX (5864 J·g−1) • The ε-CL20 stabilized as β-polymorph in CL20/BTATz & lowest sensitivity (20.5 J) • These ideal for propulsion applications & suitable for industrial scale production. Coagglomerated crystals (CACs) of the cyclic nitramines RDX, β-HMX, BCHMX and ε-CL20 with 3,6-bis(1H-1,2,3,4-tetrazol-5-ylamino)-1,2,4,5-tetrazine (BTATZ) were prepared using the "coagglomeration method" (classified as slurry cocrystallization) in two parallel batches, one with a linear stirrer (B1) and another with a cross stirrer (B2). The batch B2 procedure is more suitable because the CACs show a better crystal morphology, higher density, and quality of the crystal surface. These CACs, characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, Raman studies, and differential thermal analysis, convincingly contain cocrystals, in which HMX is stabilized in its α form and CL20 in its β form. On the basis of the results obtained, new relationships were found between the N–N bond stretching and FTIR C–H bond stretching vibrations in CACs, on the one hand, and their impact sensitivity, crystal density, voluminous detonation energy (Q.ρ), heat of combustion and enthalpy of formation, on the other. These evidence that, together with the relation between ring deformation vibrations and the Q.ρ values, correspond to the idea of the method of initiation of energetic materials by impact and shock. The α-HMX/BTATz, prepared by method B2, was surprisingly the least sensitive (46 J) of the CACs studied and had a slightly better detonation energy than that of pure β-HMX (6097 versus to 5864 J·g−1). [ABSTRACT FROM AUTHOR]

Coagglomerated crystals of HNS and HNAB with attractive nitramines [Display omitted] • CACs of HNS (–CH = CH–) and HNAB (-N = N-) with nitramines prepared results were compared. • Spectral & PXRD outputs indicate the formation of co-crystals in co-agglomeration. • HMX converted from β to δ, and CL20 ε to β modifications in co-agglomeration. • CACs with HNS can be less sensitive and more efficient than analogous PBXs. • HMX/HNS can be suitable fillers for special detonators and insensitive ammunition. Co-agglomerated crystals (CACs) of trans -2,2,4,4′,6,6′-hexanitrostilbene (HNS) and trans -2,2′,4,4′,6,6′-hexanitroazobenzene (HNAB) with RDX, β -HMX, BCHMX and ε -CL-20 have been prepared. Powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), Raman studies and differential thermal analysis (DTA) have confirmed that this process leads to the formation of co-crystals (CCs), in which HMX is present in its δ-form, CL-20 in its β -form and trans -HNS changes its conformation to cis -form. In most cases, these significant structural changes and intermolecular-orientations have improved the impact sensitivities, mainly in some CACs with cis -HNS; for CL-20, on the other hand, the insertion of HNS or HNAB into its crystal lattice is destabilizing. Logical relationships between some FTIR, Raman vibrational modes of the CACs studied and parameters of their initiation and detonation have shown greater information about corresponding molecular structural relationships. The detonation energies of these co-crystals are in most of cases higher than that of correspond to the percentage of the coformers in them. It has been shown that this co-agglomeration can reduce the sensitivity of nitramines (with the exception of CL-20) roughly to the level of the sensitivity of analogous plastic-bonded explosives (PBXs), with the high-performance parameters of the resulting CACs being maintained. From a practical point of view, the combination of HMX and HNS appears to be the most optimal; these CACs at a molar ratio of 1.00/0.11 have exhibited the impact sensitivity of 47 J and the calculated detonation velocity 8.98 km.s−1. [ABSTRACT FROM AUTHOR]

The RDX, HMX, and AP are currently the most widely used energetic ingredients in composite solid propellants, since the newly developed energetic compounds are still unable to replace them due to various bottleneck technical problems. In order to improve their combustion efficiency and performance, a common alternative way is to utilize novel nano-sized energetic additives. There are a great many nanomaterials that have been developed in the past decades, which include nanometal particles, metal oxides, metal salts, metallic composites, organometallic compounds, energetic nanocatalysts, and carbon nanomaterials. These additives could increase both the decomposition and the burning rate as well as enhance the combustion efficiency of the corresponding solid propellants by changing the thermal conductivity, energy barrier of thermolysis, heat of reaction, and gas-phase reaction mechanisms of the main ingredients such as RDX, HMX, and AP. This review paper discusses and summarizes the effects of abovementioned nano additives on decomposition kinetics, reaction models, decomposition mechanisms and burning rates, pressure exponents, combustion wave structures, and flame propagation of RDX-, HMX-, and AP-based energetic compositions. The catalytic mechanisms associated with different types of nanomaterials are explained and clarified. Owing to their extremely large specific surface areas, nano-sized energetic additives have significant catalytic effects in both condensed and gas phases during decomposition and subsequent combustion via activation of the reactants and acceleration of their transition state formations. The flame structures of AP-based composite propellants under the effect of some nanoadditives are presented showing the enhanced burning characteristics and stabilized combustion process. [ABSTRACT FROM AUTHOR]

Energetic co-agglomerates (CACs), obtained by agglomeration of the nano-particle mixtures of 1,3,5-trinitrobenzene-2,4-diamine (DATB) with nitramines, and their impact sensitivities: here Cp1 & Cp2 are BCHMX/DATB; Cp3 is RDX/DATB; Cp4 is δ-HMX/DATB; Cp5 is β-CL20/DATB. [Display omitted] • A New method co-agglomeration crystal of the nitramines with DATB. • Formation of co-crystals during co-agglomeration. • Polymorphic change β to δ in HMX and ε to β in Cl20 their co-crystals. • Uniform distributed DATB over HMX makes stable towards external stimuli. • Strong co-relation co-crystals energy content to their N-N and N-O bonds stretching. A new method of atmospheric co-agglomeration of energetic micro-particles has been applied to the preparation of the co-agglomerates of 1,3,5-trinitrobenzene-2,4-diamine (DATB) with 1,3,5-trinitro-1,3,5-triazine (RDX), 1,3,5,7-tetranitro-1,3,5,7-tetraazoctane (HMX), cis -1,3,4,6-tetranitrooctahydroimidazo[4,5–d]imidazole (BCHMX) or 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12- hexaazaisowurtzitane (CL-20). The possible benefits of this method also for the alone production technology of the used nitramines are mentioned. Raman, FTIR and PXRD techniques have proven that resulting co-agglomerates (CACs) are co-crystals (CCs), where HMX is presented in its ȏ-modification and CL-20 in its ß-modification. Thermal analyses of these CCs have shown that the stability has increased in the BCHMX/DATB and decreased in the other CCs prepared. The impact sensitivity has decreased in the RDX and HMX CCs. In BCHMX CCs, this decrease is very low. In the case of ß-CL-20/DATB, its sensitivity is high; this increase is also explaineds in the context of impact sensitivity of a "common" quality of CL-20 in general. Attention is also paid to the relationships between thermochemical, performance- and impact-sensitivity characteristics in correlation with some Raman and FTIR outputs, confirming the formation of co-crystals during co-agglomeration. All these mentioned relationships represent a new insight on the co-crystals investigation. The density of the co-crystals prepared exceeds 99% of the theoretical maximum density of the starting nitramines. Their performance is higher than would correspond to a simple calculation based on the percentage of individual components. [ABSTRACT FROM AUTHOR]