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 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
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
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
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
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
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 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
The relationship between the crystal lattice free volume,ΔV,and impact sensitivity,E_(dr),of ten nitramines has been analyzed. It was found that this relationship is not uniquely determined,i. e. it is not given only...The relationship between the crystal lattice free volume,ΔV,and impact sensitivity,E_(dr),of ten nitramines has been analyzed. It was found that this relationship is not uniquely determined,i. e. it is not given only by their own ΔV values but fundamentally by the type and intensity of the intermolecular forces in the nitramine crystals. Also,relationships between the E_(dr)values,on the one hand,and bulk modulus,K,and shear modulus,G,on the other,have been the subject of discussion not only for pure cyclic nitramines but also for their PBXs,bonded by a poly-fluoro binder. The closest linear correlation exists between the E_(dr)values and dimensionless K·G^(-1) ratio which indicates the plasticity range. A similar relationship is valid also for the ΔV values. Relationships of the E_(dr) and / or ΔV values with the shear modulus or to the K·G^(-1) ratio reflect an unusual behavior of ε-HNIW to which the published morphological instability of this particular HNIW version might also be related.展开更多
On the basis of the structural and electronic properties of 14 different cyclic nitramine molecules, two types of formulas are employed to predict their electric spark sensitivity. One contains the minimum Mulliken ch...On the basis of the structural and electronic properties of 14 different cyclic nitramine molecules, two types of formulas are employed to predict their electric spark sensitivity. One contains the minimum Mulliken charges of nitro group, the ratio of hydrogen to oxygen, and the ratio of carbon to oxygen; the other contains the lowest unoccupied molecular orbital energy, the ratio of hydrogen to oxygen, and the ratio of carbon to oxygen. Using these two types of formulas, we calculate the electric spark sensitivity of these 14 cyclic nitramine molecules, and compare them with the experimental data and previous theoretical values. And our investigations show that the former type of formula is better than the latter on predicting the electric spark sensitivity for cyclic nitramine molecules.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
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
Main observation and conclusion Important progress has been made in the development of energetic molecules with high performance by computer-aided molecular design in recent years,but structural novelty of organic sca...Main observation and conclusion Important progress has been made in the development of energetic molecules with high performance by computer-aided molecular design in recent years,but structural novelty of organic scaffolds is insufficient.In this work,we propose an intra-ring bridging strategy inspired by the known energetic nitramines to design novel polycyclic and cage energetic molecules.More than 100 energetic structures were designed by introducing the C—C bridges and increasing the ring size.The synthesis difficulty is considered besides the two most concerned properties of EMs,energy and safety.After a comprehensive estimation,a symmetric cage molecule labeled as 8U-30 was finally selected because of its relatively high detonation performance,and comparable impact sensitivity as well as synthetic accessibility with CL-20.Hopefully,the proposed strategy could be utilized in further molecular design to gain various scaffolds,especially cage structures,for different demands.展开更多
Molecular surface electrostatic potentials V_S(r) ( ESP) of seventeen nitramines have been calculated. As a criterion of the imbalance between the maximum positive,V_(S,max) and minimum negative,V_(S,min),values of mo...Molecular surface electrostatic potentials V_S(r) ( ESP) of seventeen nitramines have been calculated. As a criterion of the imbalance between the maximum positive,V_(S,max) and minimum negative,V_(S,min),values of molecular surface electrostatic potentials their sum was derived and used as a new simple characteristic for ESPs-V_(S,Σ). These V_(S,Σ) values have close relationships with the Arrhenius parameters,activation energy E_a and preexponent log A,of thermal decomposition of the nitramines studied. The correlation between the V_(S,Σ) values and heats of fusion of the nitramines studied is described. These findings suggested analyzing the physico-chemical behavior of the nitramine crystals during this decomposition; in this connection an investigation was carried out using isothermal thermogravimetry and scanning electron microscopy of thermally exposed crystals of cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole( sintering of its crystal surfaces),of β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane( cracking of its crystals during β !δ transition) and of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane. The results suggest a need to study the pre-decomposition states on thermal decomposition of the nitramines' molecule's crystals.展开更多
TEX, a well-known nitramine type explosive, has been subjected to centric perturbations by replacing its etheric(acetal) oxygens with nitrogen atoms one by one. The structural features, stabilities and IR and UV-VIS s...TEX, a well-known nitramine type explosive, has been subjected to centric perturbations by replacing its etheric(acetal) oxygens with nitrogen atoms one by one. The structural features, stabilities and IR and UV-VIS spectra of new structures formed are investigated. For this purpose, density functional theory has been employed at the B3LYP/6-31G(d,p) and B3LYP/6-311G(d) levels. In general the calculations revealed that the oxygenenitrogen replacement resulted in more energetic but less sensitive structures than TEX.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
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.
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 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.
文摘The relationship between the crystal lattice free volume,ΔV,and impact sensitivity,E_(dr),of ten nitramines has been analyzed. It was found that this relationship is not uniquely determined,i. e. it is not given only by their own ΔV values but fundamentally by the type and intensity of the intermolecular forces in the nitramine crystals. Also,relationships between the E_(dr)values,on the one hand,and bulk modulus,K,and shear modulus,G,on the other,have been the subject of discussion not only for pure cyclic nitramines but also for their PBXs,bonded by a poly-fluoro binder. The closest linear correlation exists between the E_(dr)values and dimensionless K·G^(-1) ratio which indicates the plasticity range. A similar relationship is valid also for the ΔV values. Relationships of the E_(dr) and / or ΔV values with the shear modulus or to the K·G^(-1) ratio reflect an unusual behavior of ε-HNIW to which the published morphological instability of this particular HNIW version might also be related.
基金the National Natural Science Foundation of China (Nos. 11176020 and 10976019)
文摘On the basis of the structural and electronic properties of 14 different cyclic nitramine molecules, two types of formulas are employed to predict their electric spark sensitivity. One contains the minimum Mulliken charges of nitro group, the ratio of hydrogen to oxygen, and the ratio of carbon to oxygen; the other contains the lowest unoccupied molecular orbital energy, the ratio of hydrogen to oxygen, and the ratio of carbon to oxygen. Using these two types of formulas, we calculate the electric spark sensitivity of these 14 cyclic nitramine molecules, and compare them with the experimental data and previous theoretical values. And our investigations show that the former type of formula is better than the latter on predicting the electric spark sensitivity for cyclic nitramine molecules.
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).
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.
基金support from the National Natural Science Foundation of China(Nos.21875184,21978311)the Youth Talent of Shaanxi"TeZhi"Programproject sponsored by Xi’an Modern Chemistry Research Institute(WDZCKYXM20190101).
文摘Main observation and conclusion Important progress has been made in the development of energetic molecules with high performance by computer-aided molecular design in recent years,but structural novelty of organic scaffolds is insufficient.In this work,we propose an intra-ring bridging strategy inspired by the known energetic nitramines to design novel polycyclic and cage energetic molecules.More than 100 energetic structures were designed by introducing the C—C bridges and increasing the ring size.The synthesis difficulty is considered besides the two most concerned properties of EMs,energy and safety.After a comprehensive estimation,a symmetric cage molecule labeled as 8U-30 was finally selected because of its relatively high detonation performance,and comparable impact sensitivity as well as synthetic accessibility with CL-20.Hopefully,the proposed strategy could be utilized in further molecular design to gain various scaffolds,especially cage structures,for different demands.
文摘Molecular surface electrostatic potentials V_S(r) ( ESP) of seventeen nitramines have been calculated. As a criterion of the imbalance between the maximum positive,V_(S,max) and minimum negative,V_(S,min),values of molecular surface electrostatic potentials their sum was derived and used as a new simple characteristic for ESPs-V_(S,Σ). These V_(S,Σ) values have close relationships with the Arrhenius parameters,activation energy E_a and preexponent log A,of thermal decomposition of the nitramines studied. The correlation between the V_(S,Σ) values and heats of fusion of the nitramines studied is described. These findings suggested analyzing the physico-chemical behavior of the nitramine crystals during this decomposition; in this connection an investigation was carried out using isothermal thermogravimetry and scanning electron microscopy of thermally exposed crystals of cis-1,3,4,6-tetranitrooctahydroimidazo-[4,5-d]imidazole( sintering of its crystal surfaces),of β-1,3,5,7-tetranitro-1,3,5,7-tetrazocane( cracking of its crystals during β !δ transition) and of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane. The results suggest a need to study the pre-decomposition states on thermal decomposition of the nitramines' molecule's crystals.
文摘TEX, a well-known nitramine type explosive, has been subjected to centric perturbations by replacing its etheric(acetal) oxygens with nitrogen atoms one by one. The structural features, stabilities and IR and UV-VIS spectra of new structures formed are investigated. For this purpose, density functional theory has been employed at the B3LYP/6-31G(d,p) and B3LYP/6-311G(d) levels. In general the calculations revealed that the oxygenenitrogen replacement resulted in more energetic but less sensitive structures than TEX.
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.
