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The article presents experimental results of research concerning the action of weak electric and magnetic fields on physicochemical transformations in samples of hard coal with a previously destabilized microstructure. The actions of electric and magnetic fields are fundamentally different by many parameters. It has been shown that after treatment with a weak electric field, coal posted an electret potential with an anomalously continuous charge relaxation. Compared to untreated coal samples, the rate of methane emission from methane-saturated samples is maximum for long-flame coal and decreases as it approaches anthracite. The electric field stimulates the grinding of microparticles, a decrease in the maximum gas outlet temperature, a decrease in the enthalpy value in the formation of a new phase, and an increase in the chemical activity of treated coal samples. Fundamentally different results were obtained with magnetic stimulation of coals. In X-ray diffractograms of coal powders after magnetic treatment, the values of the maxima of the main peaks are the largest in comparison with the original samples and those treated with an electric field, which is consistent with an increase in the size of microparticles in a magnetic field. There is an increase in the heat of combustion and a decrease (by 5 times) in the loss of coal mass during heating. [ABSTRACT FROM AUTHOR]

The properties of azido-acetylenic derivatives of s-triazine containing various combinations of propynyloxy, propynylamino, N-methyl-propynylamino, and azido groups have been studied, and their enthalpy of formation in the condensed phase, density, and impact and friction sensitivities have been determined. Based on these data, the energy parameters of detonation, combustion, and adiabatic transformation for individual compounds and their compositions with the binder SKI-3 isoprene rubber have been calculated. The results of the integrated experimental and theoretical studies suggest a high heat of combustion of the investigated individual compounds and compositions based on them. [ABSTRACT FROM AUTHOR]

The heat of combustion and the enthalpy of formation of 7,7′-bis(terfurazan[3,4-b:3,4′-d:3″,4″-f]azepine (I) and 1,1′-dioxide-7,7′-bis(terfurazan[3,4-b:3,4′-d:3″,4″-f] azepine (II), were experimentally determined. Product I was studied by X-ray diffraction analysis, and its crystallographic characteristics were determined. The efficiency of using compounds I and II as components of solid composite propellants was analyzed, and the type of compositions in which they are more effective than HMX was determined. [ABSTRACT FROM AUTHOR]

The heat of combustion and enthalpy of formation of bis(4 ″ -nitro[3,3 ′ :4 ′ ,3 ″ ]terfurazan-4-yl)-diazene (DNFNF) and (bis(4 ″ -azido-[3,3 ′ :4 ′ ,3 ″ ]terfurazan-4-yl)-diazene (DAzFNF) were first experimentally determined. It is found that the energy increment for replacing the nitro group with an azide group in the furazan cycle averages 290 kJ/mol and is close to the increment for replacing NO2 with N3 in trinitroethane. The dependence of the energy parameters of metal-free rocket propellants based on a mixture of ammonium perchlorate and DNFNF or DAzFNF with an active binder on the content of the high-enthalpy component in the formulation was studied by thermodynamic analysis. [ABSTRACT FROM AUTHOR]

The standard enthalpy of formation of 1,4-diethynylbenzene experimentally to be 500.6 ± 6.7 kJ/mol. Calculations show that 1,4-diethynylbenzene has a relatively high adiabatic combustion temperature (about 1970 K at a pressure of 5 atm) and very high heat of combustion in oxygen (42 MJ/kg); therefore, 1,4-diethynylbenzene can be used as the basis to develop an effective dispersing agent of solid fuel that provides an adiabatic combustion temperature of up to 2500 K at a heat of combustion far exceeding the values provided by HMX and the other azides of N-heterocycles previously proposed for this purpose. [ABSTRACT FROM AUTHOR]

The heat of combustion and the standard enthalpy of formation of 3,4-bis(4-azidofurazan-3-yl)furoxan (DAzFF) and 4-azido-4″-nitro-3,3′:4′,′3′-terfurazan (AzNTF) were experimentally determined. Thermodynamic analysis was performed to investigate the efficiency of these compounds as potential components of metal-free solid composite propellants based on an active binder with the possibility of introducing an additional small amount of oxidizer with a high oxygen content, e.g., ammonium perchlorate. [ABSTRACT FROM AUTHOR]

The progression of chemical reactions is determined by both thermodynamics and kinetics factors. Micropyretic/combustion reaction is a cascade of many chain chemical reactions and thermodynamics and kinetics of the ignition reaction are expected to greatly affect the overall reaction outcome. Furthermore, the stability of the sequential reaction and its progression are correspondingly changed once micropyretic parameters are changed. Improper ignition of micropyretic reaction provides either excessive or insufficient external energy, thus causes over-heating or extinguishing of the combustion front during propagation and therefore the heterogeneous structures. To achieve the homogeneous micropyretic reaction, it is thought possible to control ignition energy. A numerical study on the correlation of thermodynamics and kinetics factors of ignition on the stable Ni + Al reaction and the required ignition energy is reported in this study. The influences of activation energy ( E), enthalpy of the micropyretic reaction ( Q), pre-exponential factor ( K o), thermal conductivity ( K), heat capacity ( C p ), and thermal activity of the reactants and product, on the temperature/heat loss at the ignition spot and the length of pre-heating zone are respectively studied. It is found that the activation energy and heat capacity have the most significant effects on the ignition energy. The required ignition energy is increased by 44.0% and 23.9%, respectively, when the activation energy and the heat capacity are both increased by 40.0% [ABSTRACT FROM AUTHOR]