Vol 43, No 1 (2024)

A method for constructing the space of medium states in reactions of ultrafast multistage intramolecular electron transfer in media with several relaxation times is developed. The method uses the splitting of polarization coordinates into relaxation components, and is a generalization of two previously developed approaches used (1) to describe multistage reactions, and (2) to consider multicomponent relaxation. Within the suggested generalized scheme, a model of charge transfer in a three-center molecular system in the environment with a two-component relaxation function is considered, an algorithm for constructing the diabatic free energy surfaces of electronic states is described, a system of equations for the evolution of the distribution functions is written. The results of the general model are shown to reproduce well-known solutions in particular cases.

The paper presents the study of the calculated physicochemical properties of new high-energy 5/6/5 tricyclic structures, which are 1,2,3,4- or 1,2,4,5-tetrazines, fused with a pair of 1H-1,2,4-, 4H-1,2,4- or 1H-1,2,3-triazoles. Values of the enthalpy of formation in the gaseous phase have been determined by high-performance quantum-chemical calculations (within Gaussian 09 program package) using various methods for solving the stationary Schrödinger equation, including G4, G4MP2, ωB97XD/aug-cc-pVTZ, CBS-APNO, CBS-QB3, CBS-4M, B3LYP/6-311+G(2d,p), M062X/6-311+G(2d,p). The results of calculations obtained by the methods of atomization and isogyric reactions have been analysed. Various calculation methods have been compared in terms of accuracy and time consumption.

The kinetics of hydrogen cathodic reduction on low-carbon steel in a sulfuric acid solution containing a mixture of quaternary ammonium salts (catamine AB) and 3-substituted 1,2,4-triazole (IFKhAN-92 inhibitor) has been studied. The main rate constants of the stages of evolution of gaseous hydrogen and the permetion of hydrogen atoms into the metal are determined. It is shown that these substances reduce the reaction rate of the discharge of H⁺ ions, change the ratio between the concentrations of H atoms on the surface and in the phase of the metal, and, as a result, reduce the amount of hydrogen absorbed by steel. The most effective inhibitor of corrosion and hydrogenation of steel is IFKhAN-92, due to the formation of a polymolecular protective layer of the inhibitor on the metal surface. The data of X-ray photoelectron spectroscopy of the steel surface show that the protective layer has a thickness of no more than 4 nm and consists of IFKhAN-92 molecules associated with the steel surface by chemical interaction, and inside the layer by physical interaction.

Estimates have been made showing that when an exothermal reaction proceeds in an isothermal medium (in a thermostat), self-heating occurs, the values of which are determined by the competition between the processes of heat input and heat removal. Relationships are obtained that make it possible to estimate the deviation of the observed values of the kinetic parameters from the true values and to reveal the influence of various parameters on these deviations.

The enthalpies of combustion and enthalpies of formation of three trinitromethyl derivatives of 1,3,5-triazine were determined by calorimetric method. The data obtained can be used for calculating the energy capabilities of related compounds by the method of replacing functional groups. As an example, the detonation characteristics of high-energy tris(trinitromethyl)-1,3,5-triazine are calculated.

The results obtained show that the addition of aluminum (Al) and aluminum hydride (AlH₃) to the explosive significantly increases the heat of explosion and the TNT equivalent (TE) of an underwater explosion. The compositions with AlH₃ are inferior to the Al-containing counterparts in the heat of explosion. However, the formulations with AlH₃ have the advantage in terms of the number of moles of gaseous products. Replacing Al with AlH₃ weakly affects the TE in terms of the energy of gas bubble, while the TE in terms of the energy of shock wave is higher for the mixtures with AlH₃. The latter is especially noticeable in the case of the explosive with a positive oxygen balance. However, the compositions with AlH₃ are inferior to the Al-containing mixtures in the volumetric TE.

The mechanism of phase formation from (1) the initial and (2) the mechanically activated mixture of Sm₂O₃ + + MoO₃ oxides has been studied by DSC in an oxygen atmosphere. It is shown that different mechanisms of samarium oxymolybdate synthesis are realised in these two cases. As a result of the mechanochemical action at room temperature, a nano-sized mixture of Sm₂(MoO₄)₃ and Sm₂O₃ was obtained. Upon heating, the first stage is the crystallisation of Sm₂(MoO₄)₃, whose interaction with Sm₂O₃ in the second stage at 900 °C leads to the synthesis of oxymolybdate Sm₂MoO₆ with the scheelite structure, and this structure type is stable up to 1400 °C. The kinetic experiment in a DSC cell shows only an apparent similarity of the phase formation mechanism with a decrease of the main exoeffects by 70 °C for a mechanically activated mixture of oxides. At the same time, the study of the mechanism of phase formation by isothermal exposure at different temperatures reveals the main advantages of ceramic synthesis from an activated oxide mixture:

1. partially mechanosynthesis of the intermediate compound Sm₂(MoO₄)₃ takes place at room temperature;
2. the high degree of interaction between the mechanically activated oxides allows single phase ceramics to be synthesised in a single step over a wide temperature range.

The total conductivity of Sm₂MoO₆ with a scheelite structure, which turned out to be p-type (1 · 10⁻⁶ S/cm at 600 °C), was studied.

The influence of the direction of a constant electric field on the properties and structural features of thin films of nitrile rubber (NBR) formed on copper substrates from a solution in chloroform has been studied. It is shown that the greatest effect in the modification of properties associated with structural transformations in the process of formation of elastomer films occurs on the negative electrode - the cathode, when the electric field lines are directed to the electrode surface. The method of differential scanning calorimetry shows the structural differences between films formed outside and in the presence of electric fields. The films formed in the fields have different electrical characteristics from the films formed outside the field. IR spectroscopy methods confirmed the structuring and cyclization of BNKS molecules on the surface of the film formed on the cathode.

Composites based on indium oxide containing different amounts of zinc oxide were synthesized by hydrothermal and impregnation methods. The phase composition, structure, and specific surface of the obtained composites were studied by various physicochemical methods. The electrophysical properties of composites synthesized by different methods are compared. It is shown that the method of formation has a significant effect on the structural characteristics of the composites, which in turn leads to the implementation of various conduction mechanisms.