A New Aspect of Relationships between Electric Spark Sensitivity and Thermal Stability of Some Polynitro Arenes（英）

An ESZ KTTV instrument of a new,relatively simple construction has been applied to determination of electric spark sensitivity of 29 polynitro arenes,expressed as spark energy,EES,required for 50-percent initiation probability.The thermal stability thresholds,Tmax,were calculated from the published Arrhenius parameters of monomolecular thermal decomposition of the studied compounds,predominantly obtained under the conditions of the Russian manometric method.An approximate relationship has been found between the ln EES values and threshold Tmax values.In the sense of this relationship,the compounds studied fall into several sub-groups.The reason of the said diversification lies in the decomposition reaction rate at the temperature of onset of their thermal decomposition.It has been found that in each sub-group increasing thermal stability of polynitro arenes is accompanied by increasing electric spark sensitivity of these substances.This fact must be taken into account if we deal with the problem of electric spark energy transfer into the reaction centre of the molecule.     

多硝基芳烃静电火花感度与爆速的关系（英）

通过测定３２种多硝基芳烃的静电火花感度,建立了５０％发火能量ＥＥＳ与爆速平方值的关系式。试式不仅体现出Ｅｖａｎｓ－Ｐｌａｎｙｉ－Ｓｅｍｅｎｏｖ关系,而且 起爆、初始分解或由静电火花引起的能量转换过程中多硝基化合物分子初始分裂时化学是的同一性。但电火花能转至分子反应中心的方式还不茂清楚     

Evaluation of the effectiveness of features selected by discriminant analysis methods

New theoretical and practical results concerning the use of discriminant analysis for feature selection are presented in the paper. Numerical values for the eigenvalues of the matrix SW_W⁻¹ S_B (within-class and between-class scatter matrices) are investigated. An analytic expression for their minimum value representing the minimum effectiveness is derived. Differences between real values and these minimum values are important for the evaluation of the effectiveness of features and thus for feature selection.     

Sensitivity and Performance of Energetic Materials

This paper provides an overview of the main developments over the past nine years in the study of the sensitivity of energetic materials (EM) to impact, shock, friction, electric spark, laser beams, and heat. Attention is also paid to performance and to its calculation methods. Summaries are provided of the relationships between sensitivity and performance, the best representations for the calculation methods of performance being the volume heat of explosion or the product of crystal density and the square of detonation velocity. On the basis of current knowledge, it is possible to state that a single universal relationship between molecular structure and initiation reactivity does not yet exist. It is confirmed that increasing the explosive strength is usually accompanied by an increase in the sensitivity. In the case of nitramines this rule is totally valid for friction sensitivity, but for impact sensitivity there are exceptions to the rule, and with 1,3,5‐trinitro‐1,3,5‐triazepane, 1,3,5‐trinitro‐1,3,5‐triazinane, β‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane, and the α‐, β‐ and ε‐polymorphs of 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane the relationship works in the opposite direction. With respect to the QSPR approach there might be reasonably good predictions but it provides little insight into the physics and chemistry involved in the process of initiation.     

Physico-chemical properties of ethanol – Compilation of existing data

Physico-chemical properties of ethanol and aqueous solutions of ethanol are important for chemical engineering calculation, modelling and evaluation of processes during ethanol production and its use for food and non-food applications. The majority of these properties are possible to find in handbooks and tables as Yaws (1999): Chemical Properties Handbook; Miller and Yaws (1976): Correlation constants for liquids; Lide (2007–2008): CRC Handbook of Chemistry and Physics; Hole?ek (2007): Chemical-engineering tables; Critical Data Tables and other literature. Some of them are also accessible online. The goal of this paper is to present the formulas and developed algorithms for calculation of extended properties of ethanol collected from literature. Extended properties include density, vapor pressure, surface tension, viscosity, molar and specific heat capacity, enthalpy of vaporization, thermal conductivity and static relative permittivity (dielectric constant) of ethanol.     

Laser ablation of FOX-7: proposed mechanism of decomposition

A novel high-energy explosive material, FOX-7 (1,1-diamino-2,2-dinitroethylene), was studied using a combination of laser-induced breakdown spectroscopy (LIBS) and selected ion flow tube mass spectrometry (SIFT-MS). The LIBS technique uses short laser pulses (an ArF excimer laser) as the energy source to convert small quantities of a sample into plasma and to induce the emission of its molecular fragments or atoms. SIFT-MS is a novel method for absolute quantification based on chemical ionization using three reagent ions, with the ability to determine concentrations of trace gases and vapors of volatile organic compounds in real time. SIFT-MS was used to study the release of NO, NO(2), HCN, HONO, HCHO, CH(3)CH(2)OH, and C(2)H(2) after laser ablation of the explosive compound FOX-7 in solid crystalline form. The radiation emitted after excitation was analyzed using a time-resolved UV-vis spectrometer with an ICCD detector. The electronic bands of CN (388 nm), OH (308.4 nm), and NO (237.1 nm) radicals and the atomic lines of C, N, and H were identified.     

Network formation involving epoxide and carboxyl groups

Summary The base catalyzed reaction between epoxide and carboxyl groups was studied using a simple model system phenylglycidyl ether-caproic acid in the presence of triethylamine. The reaction was investigated by mass spectrometry and GPC which provide an overall qualitative and quantitative survey of all the forming reaction products. The addition esterification is followed by etherification and condensation esterification and the main reaction product, monoester, is disproportionated yielding diester and diol. In a polyfunctional system, the latter reaction may cause splitting of the polymer chain and formation of new crosslinks.     

Crystallography and Structure–Property Relationships in 2,2′,2″,2′′′,4,4′,4″,4′′′,6,6′,6″,6′′′‐Dodecanitro‐1,1′ : 3′1″ : 3″,1′′′‐ Quaterphenyl (DODECA)

X‐ray crystallographic study of 2,2′,2″,2′′′,4,4′,4″,4′′′,6,6′,6″,6′′′‐dodecanitro‐1,1′ : 3′1″ : 3″,1′′′‐quaterphenyl (DODECA) has been carried out. Nonbonding interatomic distances of oxygen atoms inside of all the nitro groups are shorter than those corresponding to the intermolecular contact radii for oxygen. By means of the DFT B3LYP/6‐31(d, p) method a difference of 136 kJ mol⁻¹ between the X‐ray and DFT structures of DODECA was found. The bearer of the highest initiation reactivity in its molecule in solid phase should be the nitro group at 4′′′‐position, in contrast to those at 2′‐ or 2″‐positions in its isolated molecule. The most reactive nitro group in the DODECA molecule can be well specified by the relationship between net charges on nitro groups and charges on their nitrogen atoms, both of them for the X‐ray structure. The ¹⁵N chemical shift, corresponding to this nitro group for the initiation by impact and shock, correlates very well with these shifts of the reaction centers of the other six “genuine” polynitro arenes.     

Characterization of Pt/SBA-15 prepared by the deposition–precipitation method

Mesoporous silica SBA-15 was prepared and loaded with Pt using the deposition–precipitation method (DP). The Pt loaded material was characterized by N₂ sorption, and X-ray diffraction (XRD) at low scattering angles as well as XRD at wide angles, in order to monitor the impact of the metal deposition pathway on the mesoporous texture. After DP the material contains ordered mesoporous silica as well as a fraction appearing as non-ordered amorphous silica. This is most likely caused by the hydrothermal treatment involved in the DP. The material was also characterized using NIR and ²⁹Si MAS NMR spectroscopy. The NIR results of the calcined materials indicate that the silanol groups of SBA-15 may act as anchoring groups for the metallic Pt particles. The NMR spectroscopy data shows that the Pt/SBA-15 sample prepared by the DP method posseses a better short-range regularity of SBA-15 walls as compared to the parent SBA-15. This is suggested to be caused by dissolution and possible re-precipitation of siliceous species.     

New aspects of initiation reactivities of energetic materials demonstrated on nitramines

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 (15)N NMR chemical shifts of nitrogen atoms of nitramino groups, on the other. In the case of the impact sensitivity, the said relationships involve the (15)N 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 (15)N 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.