Composite microcrystals of the nitramines(NAs)viz.,RDX,HMX,BCHMX,and CL-20 with electrically conductive polyaniline(PANi)are a charge transfer complexes in coagglomerated composite crystals(CACs).The activation energi...Composite microcrystals of the nitramines(NAs)viz.,RDX,HMX,BCHMX,and CL-20 with electrically conductive polyaniline(PANi)are a charge transfer complexes in coagglomerated composite crystals(CACs).The activation energies of thermolysis,E_(a),of the pure NAs and their PANi-CACs were determined using the Kissinger method,and decomposition processes are discussed.Except for the RDX/PANi CACs,all the other CACs show higher E_(a) values for decomposition compared to their pure NA counterparts.For all CACs,relationships are specified between the E_(a) values,on the one hand,and the squares of the detonation velocities,enthalpies of formation,spark energy and impact sensitivities,on the other.The relationships between their low-temperature heats of decomposition,ΔH,from DSC,and their enthalpy of formation,logarithm of impact sensitivity,electric spark energy,as well as detonation energy,are described.The PANi favorably influences the density of the corresponding CACs;surprisingly close linear correlations were found,and explained,between these densities and the E_(a) values.This presence of PANi strongly increased the electrical spark sensitivity of the CACs in comparison to the base NAs.Based on the results obtained,it can be noted in particular the exceptional desensitization of HMX to impact and the increased sensitivity to electrical spark by coating its crystals with polyaniline.展开更多
The present day weapon technology demands novel energetic materials that exhibit simultaneous high explosive yield and reduced sensitivity.This article demonstrates application of spray evaporation to prepare reduced ...The present day weapon technology demands novel energetic materials that exhibit simultaneous high explosive yield and reduced sensitivity.This article demonstrates application of spray evaporation to prepare reduced sensitive co-crystals of high performance nitramine explosives like HMX and CL-20 with a relatively less insensitive explosive 1,1-diamino-2,2-dinitroethylene or FOX-7.Stronger intermolecurar hydrogen bonding in FOX-7 is responsible for limited solubility in nost of o rganic solvents.Large solubility differences of FOX-7 with HMX and CL-20 restricts ifs co-crystallization through classical methods that yields thermodynamically favorable product.Spray flash evaporation,a kinetic crystallization method,has been therefore adopted and could successfully produce CL-20/FOX-7(2:1) and HMX/FQX-7(4:1) co-crystals.The fine powdered materials obtained were characterized by SEM,powder XRD,Raman spectro scopy,DSC-TGA etc.Multipoint Raman spectra showed consistent occurrence of spectral features indicating stoichiometric co-existence of ingredients in the crystal lattices.DSC analysis showed absence of all thermally assisted solidsolid phase transformation in the co-crystals as they were observed in pristine materials.The thermal stability calculated in terms of activation barrier fordecomposition,revealed the CL-20/FOX-7 co-crystal to be interlediately stable on comparison to their constituents while,the HMX/FOX-7 co-crystal is more stable.Compared to pure HMX and CL-20,both the co-crystals have shown higher insensitivity to impact force,suggesting them to be suitable for future generation insensitive munitions.展开更多
Fractions of β-HMX(β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane) have been used to demonstrate the mutual relationship between friction and impact sensitivities.Inclusion of an additional twelve nitramines into this sce...Fractions of β-HMX(β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane) have been used to demonstrate the mutual relationship between friction and impact sensitivities.Inclusion of an additional twelve nitramines into this scenario resulted in a series of partial relationships,which were determined from the molecular structure of these substances.It was also found that there is a relation between increasing heats of fusion of the nitramines studied and their decreasing friction sensitivities.Comparison of friction sensitivity with heats of fusion,ΔHm,tr of the studied nitramines shows that the increase in ΔHm,tr values is more or less connected with a decrease in friction sensitivity.展开更多
The relationship between friction sensitivity(FS) and the crystal lattice free space per molecule, △V. of thirteen nitramines is described by a linear equation, divided into a number of the partial relationships with...The relationship between friction sensitivity(FS) and the crystal lattice free space per molecule, △V. 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 △V values is not clearly confirmed. The influence of the △V 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, V_(int), 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.展开更多
More detailed analysis of a mutual relationship of impact sensitivity(detected by sound) and crystal lattice free volume, △V, for the 18 nitramines shows that its course is not unequivocal. For a part of the studied ...More detailed analysis of a mutual relationship of impact sensitivity(detected by sound) and crystal lattice free volume, △V, 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 AV 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.展开更多
Four kinds of nitroamine propellants with different RDX contents(10%,20%,30%and 40%)were prepared to study the effect of RDX content on the mechanical properties and combustion properties of nitroamine propellant.The ...Four kinds of nitroamine propellants with different RDX contents(10%,20%,30%and 40%)were prepared to study the effect of RDX content on the mechanical properties and combustion properties of nitroamine propellant.The mechanical properties and combustion properties of nitroamine propellant at the normal temperature(20C)and low temperature(à40C)were test by using impact testing machine,drop hammer impact test machine and closed bomb vessel.The test results show that the impact strength of30%RDX-contained nitramine propellant is maximum,but 40%RDX-contained nitramine propellant has the minimum impact strength.And the crushing height of propellant with 20%RDX-contained was the highest,but the crushing height of propellant with 40%RDX-contained the lowest.With the increase in RDX content in nitramine propellant,the energy of nitramine propellant increases and its burning rate reduces,but 40%RDX-contained nitramine propellant did not meet this trend at the low temperature because of its poor mechanical properties.展开更多
The linear, directly proportional, equations between the Arrhenius parameters(E_α, and log A) of the thermal decomposition and the crystal lattice free space per molecule, △V, of 22 nitramines are described. It is s...The linear, directly proportional, equations between the Arrhenius parameters(E_α, and log A) of the thermal decomposition and the crystal lattice free space per molecule, △V, 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 e-HNIW. These directly proportional equations mean that an increase in the △Vvalues 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 E_a 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 e-HNIW,compared with its "reduced sensitivity(RS)" or pure analogues.展开更多
The friction sensitivities(FS) of five linear and eight cyclic nitramines have been determined.These FS values were compared with the respective detonation velocities,D,and with the dimensionless ratio created by rela...The friction sensitivities(FS) of five linear and eight cyclic nitramines have been determined.These FS values were compared with the respective detonation velocities,D,and with the dimensionless ratio created by relating the heat of explosion,Qreal,to the activation energy,Ea,of non-autocatalyzed thermal decomposition of the explosives concerned.For the nitramaines studied,these comparisons show a general trend of FS decreasing with increasing energy content.展开更多
The friction sensitivity(FS) of five linear and eight cyclic nitramines has been determined.Arrhenius parameters of non-autocatalyzed thermal decomposition of these nitramines were used for comparison of the FS values...The friction sensitivity(FS) of five linear and eight cyclic nitramines has been determined.Arrhenius parameters of non-autocatalyzed thermal decomposition of these nitramines were used for comparison of the FS values with thermal reactivity.Generally,increasing values of activation energies of non-autocatalyzed decomposition of the studied nitramines are connected with decreasing FS values.A similar trend was found in the relation between FS and hypothetical initiation temperature for 5% conversion of the nitramines after 50 μs of their thermolysis,however,if in the given series of nitramines their initiation reactivity is predominantly determined by the energy content of their molecules and closer similarity of their molecular structures,then the above-mentioned trend may be opposite.The found relationships were used for prediction and verification of the activation energy of non-autocatalyzed thermal decomposition of 2,5-dinitro-2,5-diazahexane.展开更多
The friction sensitivity(FS) of five aliphatic linear and eight cyclic nitramines has been determined and correlated with DFT B3LYP/6-31-G(d,p) // 6-311+G(d,p) positive(VS,max) and negative(VS,min) extremes of molecul...The friction sensitivity(FS) of five aliphatic linear and eight cyclic nitramines has been determined and correlated with DFT B3LYP/6-31-G(d,p) // 6-311+G(d,p) positive(VS,max) and negative(VS,min) extremes of molecular surface electrostatic potentials VS(r).While there is an ambiguous relationship between the VS,max values and FS values,the decrease of FS is connected(more or less) with increase in VS,min values.展开更多
Crystal lattice free volumes,△V,of 22 nitramines introduced into relationships of maximal theoretical crystal densities(TMD),detonation velocities(D)and volume heats of explosives(ρ.Q).Values of all these characteri...Crystal lattice free volumes,△V,of 22 nitramines introduced into relationships of maximal theoretical crystal densities(TMD),detonation velocities(D)and volume heats of explosives(ρ.Q).Values of all these characteristics increase with an increase in the AV 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△V(i.e.Vint/△V),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 △V and Vint/△V 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).展开更多
Electric spark energy,E_(ES),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 re...Electric spark energy,E_(ES),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 E_(ES)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 E_(ES)values and the crystal lattice free volumes,ΔV(i.e.an increase in theΔV 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 E_(ES)values and a ratio of intrinsic volumes of molecule,V_(int),to theΔV 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,V_(S,∑).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 V_(S,∑)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 tho 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.展开更多
The composites of certain nitramine type explosives,TETRYL,RDX and EDNA,with proton in vacuum have been considered within the constraints of density functional theory at the level of B3LYP/6-31++G(d,p)(restricted and ...The composites of certain nitramine type explosives,TETRYL,RDX and EDNA,with proton in vacuum have been considered within the constraints of density functional theory at the level of B3LYP/6-31++G(d,p)(restricted and unrestricted).The results indicate that unexpectedly hydrogen molecule production occurs by the interaction of proton and a hydrogen of CH3(TETRYL)and CH2(RDX and EDNA)groups.As a result,a carbocation is generated on the explosive molecules.Thereafter,TETRYL which potentially has many protonation sites were investigated in more detail in vacuum and aqueous conditions.The data reveals that the composite system(TETRYL+proton)is less stable than TETRYL protonated on nitramine NH or oxygen of the nitro groups.展开更多
The desensitization of nitramine explosives while maintaining energetic performance is challenging.A highly efficient desensitizer is the key to solving the antinomy.This study focuses on using porous organic cages(PO...The desensitization of nitramine explosives while maintaining energetic performance is challenging.A highly efficient desensitizer is the key to solving the antinomy.This study focuses on using porous organic cages(POCs),specifically CC3 and RCC3,to desensitize RDX.By coating 0.1 wt%–5 wt%of POCs on RDX particles,a series of composite energetic materials were prepared.Characterization results show that POCs change the surface morphology of RDX,and there are interfacial interactions between them.The RDX@POCs composites exhibit enhanced stabilities in terms of heat,impact,friction,and electrostatic spark.For the RDX@RCC3-5%composite,the impact sensitivity(E_(IS)),friction sensitivity(E_(FS)),and electrostatic sensitivity(EES)were significantly reduced by 66.7%,68.8%,and 56.5%,respectively,while the detonation velocity decreased by merely 3.1%.These findings indicate that POCs,especially RCC3,are promising desensitizers for nitramine explosives,and their desensitization mechanisms likely involve barrier and buffering effects.The distinct desensitization behavior of RDX@RCC3 highlights the effectiveness of POCs in reducing the sensitivity of RDX without significantly compromising its energetic properties.展开更多
2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(HNIW), commonly called as CL-20, is a high energy and high density material of keen interest to both commercial and scientific worlds due to its greater insen...2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(HNIW), commonly called as CL-20, is a high energy and high density material of keen interest to both commercial and scientific worlds due to its greater insensitivity(reduced sensitivity) along with a positive high heat of formation, which is due to the azanitro groups attached to the skeleton of HNIW and its highly strained cage structure. It plays a remarkable role in modification and replacement of most of the propellant(gun and rocket) preparations. In this report we present the comparative strategies involved in the syntheses of HNIW with respect to economical and environmental aspects. Various methods reported in the literature on the purification of the crude HNIW(α-HNIW) to obtain ε-form of HNIW(high dense/more potential) are consolidated. Understanding of the structure, morphology, energetics, thermal behavior and their modification to meet the applicability(decreased impact sensitivity) determines the industrial application of HNIW. A compilation of the available literature on the aforementioned characteristic properties for obtaining a value added ε-HNIW is discussed here. This overview also reports the literature available on newer forms of HNIW including derivatives and cocrystals,which increase the performance of HNIW.展开更多
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 β-1,3,5,7-tetranitro-1,3...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 β-1,3,5,7-tetranitro-1,3,5-tetrazocane(β-HMX),cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole(bicyclo-HMX,BCHMX)and e-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(e-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.展开更多
Isomers of trans-1,4-Dinitroglycoluril(trans-DINGU) and their 1,3-tautomers are considered within the constraints of B3LYP/6-31ttG(d,p) and B3LYP/CC-PVTZ levels of DFT calculations. Additionally, the interactions of t...Isomers of trans-1,4-Dinitroglycoluril(trans-DINGU) and their 1,3-tautomers are considered within the constraints of B3LYP/6-31ttG(d,p) and B3LYP/CC-PVTZ levels of DFT calculations. Additionally, the interactions of these isomers and proton in vacuum are investigated. The data have revealed that two of the three isomers undergo C — H bond cleavage as the result of interaction with proton in vacuum. The total energies, some structural properties, the calculated IR and UV spectra are discussed.展开更多
基金funding from the Student Grant Project no.SGS_2022_003 of the Faculty of Chemical Technology at the University of Pardubice Czechia.
文摘Composite microcrystals of the nitramines(NAs)viz.,RDX,HMX,BCHMX,and CL-20 with electrically conductive polyaniline(PANi)are a charge transfer complexes in coagglomerated composite crystals(CACs).The activation energies of thermolysis,E_(a),of the pure NAs and their PANi-CACs were determined using the Kissinger method,and decomposition processes are discussed.Except for the RDX/PANi CACs,all the other CACs show higher E_(a) values for decomposition compared to their pure NA counterparts.For all CACs,relationships are specified between the E_(a) values,on the one hand,and the squares of the detonation velocities,enthalpies of formation,spark energy and impact sensitivities,on the other.The relationships between their low-temperature heats of decomposition,ΔH,from DSC,and their enthalpy of formation,logarithm of impact sensitivity,electric spark energy,as well as detonation energy,are described.The PANi favorably influences the density of the corresponding CACs;surprisingly close linear correlations were found,and explained,between these densities and the E_(a) values.This presence of PANi strongly increased the electrical spark sensitivity of the CACs in comparison to the base NAs.Based on the results obtained,it can be noted in particular the exceptional desensitization of HMX to impact and the increased sensitivity to electrical spark by coating its crystals with polyaniline.
基金Defense Research&Development Organization(DRDO),India for financial support towards this study。
文摘The present day weapon technology demands novel energetic materials that exhibit simultaneous high explosive yield and reduced sensitivity.This article demonstrates application of spray evaporation to prepare reduced sensitive co-crystals of high performance nitramine explosives like HMX and CL-20 with a relatively less insensitive explosive 1,1-diamino-2,2-dinitroethylene or FOX-7.Stronger intermolecurar hydrogen bonding in FOX-7 is responsible for limited solubility in nost of o rganic solvents.Large solubility differences of FOX-7 with HMX and CL-20 restricts ifs co-crystallization through classical methods that yields thermodynamically favorable product.Spray flash evaporation,a kinetic crystallization method,has been therefore adopted and could successfully produce CL-20/FOX-7(2:1) and HMX/FQX-7(4:1) co-crystals.The fine powdered materials obtained were characterized by SEM,powder XRD,Raman spectro scopy,DSC-TGA etc.Multipoint Raman spectra showed consistent occurrence of spectral features indicating stoichiometric co-existence of ingredients in the crystal lattices.DSC analysis showed absence of all thermally assisted solidsolid phase transformation in the co-crystals as they were observed in pristine materials.The thermal stability calculated in terms of activation barrier fordecomposition,revealed the CL-20/FOX-7 co-crystal to be interlediately stable on comparison to their constituents while,the HMX/FOX-7 co-crystal is more stable.Compared to pure HMX and CL-20,both the co-crystals have shown higher insensitivity to impact force,suggesting them to be suitable for future generation insensitive munitions.
基金the project of the Ministry of Education,Youth and Sports of the Czech Republic,No.MSM 0021627501
文摘Fractions of β-HMX(β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane) have been used to demonstrate the mutual relationship between friction and impact sensitivities.Inclusion of an additional twelve nitramines into this scenario resulted in a series of partial relationships,which were determined from the molecular structure of these substances.It was also found that there is a relation between increasing heats of fusion of the nitramines studied and their decreasing friction sensitivities.Comparison of friction sensitivity with heats of fusion,ΔHm,tr of the studied nitramines shows that the increase in ΔHm,tr values is more or less connected with a decrease in friction sensitivity.
基金financial support from the Students Grant Projects No. SGSFCHT_2016002 of the Faculty of Chemical Technology at the University of Pardubicefinancial support of the Chinese State Administration of Foreign Experts Affairs
文摘The relationship between friction sensitivity(FS) and the crystal lattice free space per molecule, △V. 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 △V values is not clearly confirmed. The influence of the △V 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, V_(int), 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.
基金financial support from the Students Grant Projects No. SGSFCHT_2016002 of the Faculty of Chemical Technology at the University of Pardubicefinancial support The State Administration of Foreign Experts Affairs, Peoples Republic of China
文摘More detailed analysis of a mutual relationship of impact sensitivity(detected by sound) and crystal lattice free volume, △V, 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 AV 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.
基金supported by National Natural Science Foundation of China(NO.51506093)
文摘Four kinds of nitroamine propellants with different RDX contents(10%,20%,30%and 40%)were prepared to study the effect of RDX content on the mechanical properties and combustion properties of nitroamine propellant.The mechanical properties and combustion properties of nitroamine propellant at the normal temperature(20C)and low temperature(à40C)were test by using impact testing machine,drop hammer impact test machine and closed bomb vessel.The test results show that the impact strength of30%RDX-contained nitramine propellant is maximum,but 40%RDX-contained nitramine propellant has the minimum impact strength.And the crushing height of propellant with 20%RDX-contained was the highest,but the crushing height of propellant with 40%RDX-contained the lowest.With the increase in RDX content in nitramine propellant,the energy of nitramine propellant increases and its burning rate reduces,but 40%RDX-contained nitramine propellant did not meet this trend at the low temperature because of its poor mechanical properties.
基金support from the Students Grant Projects No.SGSFCHT_2016002 of the Faculty of Chemical Technology at the University of Pardubicefinancial support came from the Chinese State Administration of Foreign Experts Affairs
文摘The linear, directly proportional, equations between the Arrhenius parameters(E_α, and log A) of the thermal decomposition and the crystal lattice free space per molecule, △V, 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 e-HNIW. These directly proportional equations mean that an increase in the △Vvalues 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 E_a 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 e-HNIW,compared with its "reduced sensitivity(RS)" or pure analogues.
基金the project of the Ministry of Education,Youth and Sports of the Czech Republic No.MSM 0021627501
文摘The friction sensitivities(FS) of five linear and eight cyclic nitramines have been determined.These FS values were compared with the respective detonation velocities,D,and with the dimensionless ratio created by relating the heat of explosion,Qreal,to the activation energy,Ea,of non-autocatalyzed thermal decomposition of the explosives concerned.For the nitramaines studied,these comparisons show a general trend of FS decreasing with increasing energy content.
基金the project of the Ministry of Education,Youth and Sports of the Czech Republic No.MSM 0021627501
文摘The friction sensitivity(FS) of five linear and eight cyclic nitramines has been determined.Arrhenius parameters of non-autocatalyzed thermal decomposition of these nitramines were used for comparison of the FS values with thermal reactivity.Generally,increasing values of activation energies of non-autocatalyzed decomposition of the studied nitramines are connected with decreasing FS values.A similar trend was found in the relation between FS and hypothetical initiation temperature for 5% conversion of the nitramines after 50 μs of their thermolysis,however,if in the given series of nitramines their initiation reactivity is predominantly determined by the energy content of their molecules and closer similarity of their molecular structures,then the above-mentioned trend may be opposite.The found relationships were used for prediction and verification of the activation energy of non-autocatalyzed thermal decomposition of 2,5-dinitro-2,5-diazahexane.
基金the project of the Ministry of Education,Youth and Sports of the Czech Republic No.MSM 0021627501
文摘The friction sensitivity(FS) of five aliphatic linear and eight cyclic nitramines has been determined and correlated with DFT B3LYP/6-31-G(d,p) // 6-311+G(d,p) positive(VS,max) and negative(VS,min) extremes of molecular surface electrostatic potentials VS(r).While there is an ambiguous relationship between the VS,max values and FS values,the decrease of FS is connected(more or less) with increase in VS,min values.
基金funded partially by Faculty of Chemical Technology at the University of Pardubice by the financial resources of Student’s Grant Project No. SGS_2018_002partially by the financial support for a six-month traineeship in 2016 for Dr. LIU Ning in the Institute of Energetic Materials at University of Pardubice from the State Administration of Foreign Experts Affairs, Peoples Republic of China
文摘Crystal lattice free volumes,△V,of 22 nitramines introduced into relationships of maximal theoretical crystal densities(TMD),detonation velocities(D)and volume heats of explosives(ρ.Q).Values of all these characteristics increase with an increase in the AV 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△V(i.e.Vint/△V),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 △V and Vint/△V 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).
基金funded partially by the Faculty of Chemical Technology at the University of Pardubice。
文摘Electric spark energy,E_(ES),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 E_(ES)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 E_(ES)values and the crystal lattice free volumes,ΔV(i.e.an increase in theΔV 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 E_(ES)values and a ratio of intrinsic volumes of molecule,V_(int),to theΔV 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,V_(S,∑).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 V_(S,∑)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 tho 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.
文摘The composites of certain nitramine type explosives,TETRYL,RDX and EDNA,with proton in vacuum have been considered within the constraints of density functional theory at the level of B3LYP/6-31++G(d,p)(restricted and unrestricted).The results indicate that unexpectedly hydrogen molecule production occurs by the interaction of proton and a hydrogen of CH3(TETRYL)and CH2(RDX and EDNA)groups.As a result,a carbocation is generated on the explosive molecules.Thereafter,TETRYL which potentially has many protonation sites were investigated in more detail in vacuum and aqueous conditions.The data reveals that the composite system(TETRYL+proton)is less stable than TETRYL protonated on nitramine NH or oxygen of the nitro groups.
文摘The desensitization of nitramine explosives while maintaining energetic performance is challenging.A highly efficient desensitizer is the key to solving the antinomy.This study focuses on using porous organic cages(POCs),specifically CC3 and RCC3,to desensitize RDX.By coating 0.1 wt%–5 wt%of POCs on RDX particles,a series of composite energetic materials were prepared.Characterization results show that POCs change the surface morphology of RDX,and there are interfacial interactions between them.The RDX@POCs composites exhibit enhanced stabilities in terms of heat,impact,friction,and electrostatic spark.For the RDX@RCC3-5%composite,the impact sensitivity(E_(IS)),friction sensitivity(E_(FS)),and electrostatic sensitivity(EES)were significantly reduced by 66.7%,68.8%,and 56.5%,respectively,while the detonation velocity decreased by merely 3.1%.These findings indicate that POCs,especially RCC3,are promising desensitizers for nitramine explosives,and their desensitization mechanisms likely involve barrier and buffering effects.The distinct desensitization behavior of RDX@RCC3 highlights the effectiveness of POCs in reducing the sensitivity of RDX without significantly compromising its energetic properties.
基金financial assistance under the sponsored project "Novel materials for high energy reactions" (H/A: 4254) to Gulbarga University, Kalaburagi, India
文摘2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(HNIW), commonly called as CL-20, is a high energy and high density material of keen interest to both commercial and scientific worlds due to its greater insensitivity(reduced sensitivity) along with a positive high heat of formation, which is due to the azanitro groups attached to the skeleton of HNIW and its highly strained cage structure. It plays a remarkable role in modification and replacement of most of the propellant(gun and rocket) preparations. In this report we present the comparative strategies involved in the syntheses of HNIW with respect to economical and environmental aspects. Various methods reported in the literature on the purification of the crude HNIW(α-HNIW) to obtain ε-form of HNIW(high dense/more potential) are consolidated. Understanding of the structure, morphology, energetics, thermal behavior and their modification to meet the applicability(decreased impact sensitivity) determines the industrial application of HNIW. A compilation of the available literature on the aforementioned characteristic properties for obtaining a value added ε-HNIW is discussed here. This overview also reports the literature available on newer forms of HNIW including derivatives and cocrystals,which increase the performance of HNIW.
基金supported by means of the financial resources of Students Grant Projects No. SGS_2018_002 of the Faculty of Chemical Technology at the University of Pardubice
文摘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 β-1,3,5,7-tetranitro-1,3,5-tetrazocane(β-HMX),cis-1,3,4,6-tetranitro-octahydroimidazo-[4,5-d]imidazole(bicyclo-HMX,BCHMX)and e-2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(e-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.
文摘Isomers of trans-1,4-Dinitroglycoluril(trans-DINGU) and their 1,3-tautomers are considered within the constraints of B3LYP/6-31ttG(d,p) and B3LYP/CC-PVTZ levels of DFT calculations. Additionally, the interactions of these isomers and proton in vacuum are investigated. The data have revealed that two of the three isomers undergo C — H bond cleavage as the result of interaction with proton in vacuum. The total energies, some structural properties, the calculated IR and UV spectra are discussed.
