Friction Sensitivity of Nitramines. Part Ⅲ: Comparison with Detonation Performance（英）

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.     

1,3,3-trinitroazetidine (TNAZ). Study of thermal behaviour. Part II

Abstract

Thermal behavior of TNAZ (1,3,3 - trinitroazetidine) was studied by using differential scanning calorimetry (DSC), differential thermal analysis (DTA), and thermogravimetryc analysis (TGA).

It was found out that TNAZ is thermally more stable than RDX, but less stable than HMX and TNT. The reaction of intensive thermal decomposition starts at 183–230 °C, depending on heating rate, while the first exothermic reaction was observed at 178 °C at the heating rate of 1 °C/min.

By applying multiple heating rate DSC measurements and Ozawa's method the activation energy of 161.3 kJ/mol and pre-exponential factor of 8.27·10¹³ 1/s were calculated from DSC peak maximum temperature-heating rate relationship. By the same method the activation energy of 157.5 kJ/mol and pre-exponential factor of 4.55·10¹³ 1/s were calculated from DTA peak maximum temperature.

By applying Flynn-Wall isoconversional method it was calculated from DSC measurements that the activation energy equals between 140 and 155.6 kJ/mol at degrees of conversion ranging between 0.3 and 0.7, while pre-exponential factor ranges between 7.8·10¹² and 1.92·10¹³ 1/s.     

cis-1,3,4,6-Tetranitrooctahydroimidazo-[4,5-d]imidazole (BCHMX), its properties and initiation reactivity

Pre-treatment of simulated industrial wastewaters (SIM1, SIM2 and SIM3) containing organic and inorganic compounds (1,2-dichloroethane, sodium formate, sodium hydrogen carbonate, sodium carbonate and sodium chloride) by oxidative degradation using homogeneous Fenton type processes (Fe²⁺/H₂O₂ and Fe³⁺/H₂O₂) has been evaluated. The effects of initial Fe²⁺ and Fe³⁺ concentrations, [Fe^2+/3+], type of iron salt (ferrous sulfate vs. ferric chloride), initial hydrogen peroxide concentration, [H₂O₂], on mineralization extent, i.e., total organic content (TOC) removal, were studied. Response surface methodology (RSM), particularly Box–Behnken design (BBD) was used as modelling tool, and obtained predictive function was used to optimize the overall process by the means of desirability function approach (DFA). Up to 94% of initial TOC was removed after 120 min. Ferrous sulfate was found to be the most appropriate reagent, and the optimal doses of Fe²⁺ and H₂O₂ for reducing the pollutant content, in terms of final TOC and sludge production were assessed.     

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.     

On the mechanical stability of mesoporous silica SBA-15

Mesoporous silica SBA-15 was synthesised at 80 °C. The calcined solids were exposed to a unilateral external pressure in the range 16–191 MPa in order to monitor the impact of the mechanical pressure on the properties of SBA-15. N₂ adsorption–desorption measurements, XRD and UV-Raman spectroscopy was used in order to evaluate the changes occurring in the SBA-15. For the XRD measurement, an internal Si standard was used to correct the position of the SBA-15 patterns. It appeared that the elevated pressure has no influence on the hexagonal cell parameter a. Through the N₂ sorption measurements the fraction of the preserved mesoporous structure was estimated to be 60% when the highest pressure has been used. As the remaining part of the material is irreversibly disintegrated into small particles, the pressed sample is considered to be heterogeneous. However, the preserved fraction is slightly modified, showing a smaller pore width and plugs located within the mesopores. The plugs most likely originate from a disintegrated fraction of the SBA-15. UV-Raman spectroscopy shows that the relative intensity of the band associated with the siliceous network (ω₁) has decreased on the pressed samples resulting in a less ordered material possessing an enhanced population of silanols as compared to parent SBA-15. We propose that the disorder introduced by pressing is responsible for the observed expansion of the SBA-15 walls, which is detected for the samples treated at higher pressures (112, 191 MPa).     

New Aspects of the Impact Reactivity of Nitramines

The impact reactivity (“the first reaction”) of 16 nitramines was determined as the drop energy E_d, required for 50% initiation probability. Relationships have been found between the E_d values, on the one hand, and heats of fusion, ¹⁵N NMR chemical shifts of aza atoms in reaction centers, parameters of low‐temperature thermolysis, and oxygen balances of nitramines studied, on the other. Taking these relationships the E_d values were predicted for four nitramines, from which three have not been synthesized yet. On the basis of the said relationships it was stated that the impact reactivity of nitramine molecules depends on the electronic configuration within their reaction centers and on their conformational stability and intensity of their intermolecular interactions. The reaction centers here are the same as in the case of initiation of the nitramines by shock. It is found that ϵ‐HNIW possesses higher thermal and impact reactivities in comparing with those of β‐modification.     

Decomposition of some polynitro arenes initiated by heat and shock Part I. 2,4,6-Trinitrotoluene

Samples of 2,4,6-trinitrotoluene (TNT) exposed to heat or to shock and residues after their detonation have been analyzed chromatographically (LC-UV and LC/MS). It was found that the main identified decomposition intermediates are identical in all the three cases. 4,6-Dinitro-2,1-benzoisoxazole and 2,4,6-trinitrobenzaldehyde are the most reactive from them. It has been stated that the chemical micro-mechanism of the primary fragmentations of shock-exposed TNT molecules and/or its detonation transformation should be the same as in the case of its low-temperature thermal decomposition.     

Decomposition of some polynitro arenes initiated by heat and shock Part II: Several N-(2,4,6-trinitrophenyl)-substituted amino derivatives

Samples of 2,4,6-trinitroaniline (PAM), 2,4,6-trinitro-N-(2,4,6-trinitrophenyl)aniline (DPA), N,N'-bis(2,4,6-trinitrophenyl)-3,5-dinitropyridine-2,6-diamine (PYX) and N,N',N'-tris(2,4,6-trinitrophenyl)-1,3,5-triazine-2,4,6-triamine (TPM) were exposed to heat or to shock and then analysed chromatographically (LC-UV and LC/MS). It was found that the main identified decomposition products of these two incomplete initiations are identical for each of the compounds studied. It has been stated that the chemical micro-mechanism of the primary fragmentations of their low-temperature decomposition should be the same as in the case of their initiation by shock, including fragmentation during their detonation transformation.     

Influence of the energy content and its outputs on sensitivity of polynitroarenes

ABSTRACT

Among 28 polynitroarenes and their derivatives relationships are demonstrated between their impact, E_dr, and electric spark, E_ES, sensitivities, on the one hand, and the volume heats of their explosion, ρQ_max, and their enthalpies of formation, ΔH_form, on the other. While the impact sensitivity increases with increasing values of the ρQ_max variable (with certain exceptions), a change in the electric spark sensitivity in the aforesaid sense leads mostly to a decrease in this sensitivity. Taking the energy content of molecules, represented by the ΔH_form values, instead of the heat of explosion, gives ambiguous linear relationships for impact sensitivity. The semi-logarithmic relationship between the E_ES and ΔH_form values divides into sub-relationships. Both the impact and electric spark sensitivities increase with an increase in the ΔH_form values, with several exceptions in both these cases. From the results obtained is possible to see that it is necessary to distinguish between the influence of performance and the influence of energetic content of the energetic materials on their initiating reactivity.     

Vergleichende wärmetechnische Bewertung von Brennstoffen für Industrieöfen

Graphische Darstellung der thermodynamischen Grundlagen der Brennstoffbewertung durch Enthalpie-Volumen- und Temperatur-Wärmekapazität-Schaubilder. Überprüfung der bisherigen Bewertungsverfahren. Untersuchung des Einflusses des Luftüberschusses, der Verbrennungsluft- und Brennstoffvorwärmung, der Anfangstemperatur der Wärmgase, der Abgastemperatur und des Verbrennungsablaufs auf die Bewertungsrechnung.