Vol 43, No 5 (2024)

The magnetic effects (ME) of a moderate magnetic field (MF, 600 mT) on the rate of radical generation (W_i) in mixed micellar systems of quaternary ammonium compounds with hydroperoxides (QAC-ROOH), measured by the inhibitor method, and the effect of magnetic field on the rate of radical polymerization initiated by radicals, generated from the surface by QAC chemisorbed on a solid carrier upon interaction with hydroperoxide dissolved in the monomer are compared. It has been established that in micellar solutions MF reduces W_i, ME ≈ –0.45. In the case of radical polymerization of styrene containing cumyl hydroperoxide on the surface of mica plates with a chemisorbed monolayer of QAC (CTAB or ACh), the polymerization rate increases in MF.

The pressure of β-FOX-7 vapors in the temperature range 140–160 °C was determined by the manometric method. The correlation dependence of logP_vap on 1/T has been established, which makes it possible to estimate the value of P_vap with satisfactory accuracy in the temperature range of 100–200°C. The kinetics of the reaction in the gas phase was measured at temperatures of 200–230 °C and m/V = 10^–3–10^–4 g/cm³. It was found that under these conditions, in parallel with the usual monomolecular isomerization reaction into aci-form, a chain process of direct oxidation of FOX-7 by NO₂ proceeds. The consequence of this reaction is a significant decrease in the activation energy observed and the appearance of rate dependence on the experimental conditions. The scheme of the main stages of the chain reaction is presented and the conditions necessary for the manifestation of this reaction are determined.

The methods of mathematical modeling have been used to explore the initiation of combustion of a large mass of a condensed mixture in local contact with the end face of the burning layer. It is shown that the minimum width of the igniting layer is proportional to the width of the thermal front of the combustion wave. The coefficient of proportionality is determined by the initial temperature, heat and activation energy of the reaction. The calculation results can be used to estimate the effective activation energy of the reaction that controls the combustion mechanism of gasless system.

The parameters of decomposition and combustion of reed plants are formulated, which characterize combustible material and are necessary for physical and mathematical modeling of the occurrence and development of a fire, determining the risk of its consequences. According to the results of TGA, the content of the main components in the leaves and stem of the plant was estimated, the mechanism and parameters of the macrokinetics of their thermal-oxidative decomposition and pyrolysis were determined.

The effect of the ratio of the reagents on a stabilized cool flame of rich propane-oxygen mixtures is investigated. It was found that with an increase in the initial concentration of propane in the mixture, its consumption, as well as the concentration of propylene, has a maximum a ratio of C₃H₈ : O₂ = 1 : 1. In this case, the selectivity of propylene formation reaches a maximum a ratio of C₃H₈ : O₂ = 4 : 1. It is shown that an increase in the initial propane concentration in the mixture increases the yield of methane, but reduces the yield of propylene, ethylene, hydrogen, CO, CO₂, methanol, formaldehyde and acetaldehyde. At a ratio of C₃H₈ : O₂ = 6 : 1, ethane was also found in the reaction products. The possibility of ethanol formation in the reactions of ethoxyl and hydroxyethyl radicals with acetaldehyde has been analyzed using the CBS-QB3 quantum-chemical method.

In the interaction of high-molecular ammonium polyphosphate with polyethylene polyamine, thermoplastic polymers with T_g = 46.3–50.7°C, T_soft= 43–92°C, T_flow= 85–152°C are obtained. Thermal, heat resistance, moisture resistance, and the degree of crystallinity depending on the concentration of polyethylene polyamine are measured. The bending strength of polymers and reinforced composites is measured. A chemical scheme for the formation of a polycomplex is proposed and its structure is considered.

Currently, modified oxidized (intercalated) graphites and thermally expanded graphites obtained from them are used in solving many applied problems. This is due to the fact that while retaining all the properties of layered graphite compounds, split graphite particles have important new properties, such as ease of molding, low bulk density, and active interaction with the polymer matrix. However, the question of the mechanisms of expansion of oxidized graphite and the properties of thermally expanded graphite particles split into layers has not been sufficiently studied. The establishment of experimental patterns of expansion processes of graphite oxidized by acids contributes to the understanding of the set of stages of complex processes occurring during the expansion of graphite particles in a gas atmosphere and in polymer matrices. The purpose of the work was to synthesize a colloidal-graphite suspension based on thermally expanded graphite particles, to study the properties of suspensions and expansion processes of oxidized graphite during thermal and microwave heating. As a result of modifying thermally expanded graphite with low bulk density in activating media, colloidal graphite suspensions are synthesized without a vibration grinding stage. The splitting of graphite materials after chemical modification by thermal and microwave-stimulated heating leads to the formation of graphene-like structures. The development of techniques for modifying electrically conductive porous samples of materials used as electrodes makes it possible to introduce nanographite particles under the influence of an electric field.