Mass conductivity in drying of a fibre-forming polymer—Polycaproamide

The kinetics of drying and mass conductivity properties of a fibre-forming polymer—polycaproamide, were investigated. The applicability of the results obtained for engineering calculations was demonstrated. The curve of the mass conductivity coefficients as a function of the moisture content of the polycaproamide and the temperature is approximated by an empirical equation. Moscow State Textile Academy. Translated fromKhimicheskie Volokna, No. 4, pp. 44–46, July–August, 1999.     

Preexplosion phenomena in heavy metal azides

The paper reports results of investigation of the explosive decomposition of heavy metal azides in real time. The characteristics of the detected predetonation effects — the preexplosion conductance and luminescence of heavy metal azides — are described. The obtained value of the preexplosion conductivity of silver azide indicates that the process is of a chain nature. A model for the development of explosion of heavy metal azides is developed including multiplication of active particles (holes) by a first-order reaction and chain termination by a second-order reaction. Translated fromFizika Goreniya i Vzryva, Vol. 36, No. 5, pp. 78–89, September–October, 2000. This work was supported by the Russian Foundation of Fundamental Research (Grant No. 98-03-32001a) and the Foundation of the Ministry of General and Professional Education of the Russian Federation.     

Response of a cylindrical steel container to internal explosive loading with variation in the degree of water filling

Results of an experimental study of the response of cylindrical steel containers to internal explosive loading as a function of the degree of water filling are presented. The experiment was supported by numerical calculations of the system “explosive-filling medium-container.” A significant effect of the filling medium on the shape and deformation of the container was found. The main contribution is made by the compressibility of the filling medium and the ratio of its mass to the mass of the deformable walls of the container. Translated fromFizika Goreniya i Vzryva, Vol. 36, No. 4, pp. 115–130, July–August, 2000.     

Efficiency of use of bottoms from regeneration of lactam water for production of magnetoplastics

The efficiency of using bottoms from regeneration of lactam water as a polymeric thermoplastic binder for creating magnetoplastics was demonstrated. A formula for magnetoplastics with magnetic characteristics corresponding to a foreign analog — the magnetoplastic from the German firm Neofer — was developed. The magnetoplastics are chemically stable in conditions of exposure to aggressive media — machine oil and gasoline. Translated from Khimicheskie Volokna, No. 1, pp. 53–55, January–February, 1998.     

Detonation of a mixture of RDX particles partially filling a cylindrical channel

Using a mathematical model of a two-phase, two-velocity medium, detonation in an annular layer of a suspension of volatile secondary explosives adjacent to the wall of a cylindrical channel is numerically investigated. The dynamics of formation and the special features of the structures of a two-dimensional reaction zone of a detonation wave in a gas mixture of RDX particles are discussed. A detonation regime with a vortex structure of the reaction zone is obtained in calculations for the first time. The geometrical limits of detonation in a channel are determined. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 4, pp. 79–87, July–August 1999.     

Radiographic study of interaction of shock and detonation waves in a high explosive

Collisions of shock and detonation waves in an HMX-based high explosive are experimentally studied with the use of flash radiography. Based on X-ray patterns, specific features of the wave-interaction process are identified, and qualitative differences are found in detonation formation and evolution in an explosive precompressed by a weak shock wave and in an undisturbed explosive. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 3, pp. 132–138, May–June, 2007.     

Detonation Velocity of Emulsion Explosives Containing Cenospheres

The detonation velocity of an emulsion explosive containing hollow alumosilicate microspheres (cenospheres) as the sensitizer is measured. The size of the microspheres is 50–250 μm. The relations between the detonation velocity and the charge density and diameter are compared for emulsion explosives containing cenospheres or glass microballoons as the sensitizer. It is shown that for a 55 mm diameter charge, the maximum detonation velocity of the composition with cenospheres of size 70–100 μm is 5.5–5.6 km/sec, as well as for 3M glass microballoons. The critical diameter for the emulsion explosive with cenosphere is 1.5–2 times larger than that for the emulsion explosive with glass microballoons and is 35–40 mm. __________ Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 5, pp. 119–127, September–October, 2005.     

Detonation combustion of gas mixtures using a hypervelocity projectile

This paper considers, from a unified point of view, problems of initiation of detonation combustion of a gaseous mixture using a hypervelocity projectile (HVP), The consideration is based on the energy criterion forHVP-induced detonation initiation. Experimental results are given that support the correctness of the criterion in a wide range of diameters (5–250 mm),HVP velocities (800–3500m/sec), and compositions of explosive mixtures (from active fuel-oxygen to hard-to-detonate fuel-air mixtures). The processes ofHVP interaction with an explosive mixture are classified. The previously unknown effect of jet formation of a detonation wave from a ballistic wave (at velocities less than the detonation velocities) was discovered for anHVP with a plane bow. Lavrentśev Institute of Hydrodynamics, Siberian Division, of the Russian Academy of Sciences, Novosibirsk 630090. Translated from Fizika Goreniya i Vzryva, Vol. 33, No. 5, pp. 85–102, September–October, 1997.     

Model for the propagation of a stationary reaction front in a viscoelastic medium

A coupled thermomechanical model for the propagation of a stationary chemical-reaction wave in a condensed medium is developed. Stresses and strains that arise during the reaction as a result of thermal and “concentration” expansion of the material are related by Maxwell’s equations for a viscoelastic medium. The expression for the heat flux is written as a generalized Fourier law with finite relaxation time for the heat flux. It is shown that deformation of the material in the reaction zone can lead to an apparent change in the activation energy, heat effect, and other characteristics of the system. This model allows for the existence of two different — subsonic and supersonic — regimes of propagation of the front, as well as the model in which the stress- and strain-tensor components are related by a generalized Hooke’s law. Translated fromFizika Goreniya i Vzryva, Vol. 36, No. 4. pp. 41–51, July–August, 2000.     

Analysis of the parameters of sorption-desorption isotherms for highly hygroscopic fibres

Equations for describing the desorption isotherms for fibres with high hygroscopicity and curves for finding the points of inflection, the boundary between solvation and volume sorption segments are proposed and can be used for qualitatively and quantitatively evaluating the hygroscopic characteristics of fibres in a wide range of changes in the relative humidity and temperature. Equations for the equilibrium moisture content suitable for use in calculations of the kinetics of drying and other finishing processes for fibres and textile materials based on them and in processing sorption—desorption isotherms for fibres of other types are obtained. Moscow State Textile Academy. Translated fromKhimicheskie Volokna, No. 3, pp. 45–49, May–June, 1999.     

Ways of reducing the sensitivity of hexogen-bearing explosives to mechanical loads

Studies were conducted on reducing the sensitivity of fusible hexogen-bearing explosives to mechanical loads. It is shown that sensitivity can be reduced to the level of trotyl by diluting the explosive with trotyl and dinitronaphthalene, as well as by mixing it with oxyzine. A universal desensitizer — ethylene glycol — has been found for alloys of the TGA type. The addition of 5% ethylene glycol to the mixture also reduces sensitivity to the level of trotyl. Central Scientific Research Institute of Chemistry and Mechanics, 115487 Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 31, No. 6, pp. 140–146, November–December, 1995.     

Calculation-graphic analysis of the IR spectrum of a glass batch containing sodium borate and silicate and boric and silicic acids

A calculation-graphic analysis of the IR spectra of sodium borate and silicate as components of a glass batch, obtained in aqueous medium, and probable contaminants — boric and silicic acids — was conducted. It was found that several bands called critical coincide or are close together in the spectrum. Among them are the bands at 947–959, 1004–1005, 1079–1086, 1195–1200, 1450–1453, and 1686–1690 cm⁻¹ characterizing the fundamental vibrations of the atoms in bonds in cross-linking groups, and they cannot be distinguished by either the wavenumber or the intensity so that it is impossible to identify the phases formed. The concept of “conditionally distinguishable bands” in the spectra of comparable substances was introduced. The absolute degrees of difference in the wavenumber and intensity, order of sorting the bands, and determination of the boundaries of the critical regions of the spectrum of the batch were examined. __________ Translated from Steklo i Keramika, No. 8, pp. 3–8, August, 2007.     

Physicochemical properties of Al2O3 powder produced by explosive synthesis

The phase, dispersive, and morphological features of an aluminum oxide powder produced by explosive synthesis are examined experimentally. It is shown that the particle-size distribution has three distinct maxima, which are due to different combustion regimes. The relationship between the sizes and morphology of the starting powder and the product is determined. Considerable attention is given to a study of the ultrafine fraction of the product powder. The ultrafine particles are shown to have a regular spherical shape, and sinters are not revealed. Besides spherical particles, the synthesized powder contains faceted crystals. X-ray phase analysis of the ultrafine fraction of the synthesized powders shows that this fraction consists only of the metastable phases of the oxide — the δ- or oxynitride modifications. The δ-modification differs from that described in the literature. Translated fromFizika Goreniya i Vzryva, Vol. 36, No. 5, pp. 119–125, September–October, 2000. This work was supported by the INTAS Foundation (Grant No. 97-1754).     

Activated combustion of a silicon—carbon mixture in nitrogen and SHS of Si3N4—SiC composite ceramic powders and silicon carbide

It is established that Si₃N₄—SiC composites with a mass content of SiC 5–60% and a dominating content of the β-modification of silicon nitride can be produced by interaction of the components in the Si—C—N₂ system in the combustion regime. It is found that the fraction of α-Si₃N₄ can be increased by diluting the starting mixture with the end products, but this leads to the occurrence of a certain amount of unreacted silicon in the products. It is shown that the use of chemical activation allows one to perform a single-stage synthesis of Si₃N₄—SiC composites with any contents of the individual components (from 0 to 100%), including pure carbide silicon. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 5, pp. 56–62, September–October, 2006.     

Fabrication of New Water-Soluble Chitosan Derivatives

A new water-soluble derivative of chitosan — chitosan oligoethylene oxide sulfonate — was synthesized. The ratio and concentration of reacting substances and temperature and duration of the chitosan modification reaction affect the composition and properties of the reaction products. The conditions that ensure a 100% yield of water-soluble chitosan derivatives were determined. Using potentiometric titration and IR spectroscopy, the formation of a new water-soluble chitosan derivative — oligoethylene oxide sulfonate — was confirmed. __________ Translated from Khimicheskie Volokna, No. 4, pp. 41–44, July–August, 2005.     

Deformation of nonfired refractories based on phosphate binders. 6. Deformation under heating and creep in corundum composites

The results of studying heating deformation and creep are described for two systems: electrocorundum — α-Al₂O₃ — phosphate binder and electrocorundum — pyrophyllite — phosphate binder. It is shown that composites with H₃PO₄ experience less deformation than composites with the alumochromium-phosphate binder, whereas using pyrophyllite instead of aluminum oxide increases creep deformation due to the presence of the liquid phase in the material. The effect of technological factors is investigated. __________ Translated from Novye Ogneupory, No. 6, pp. 58–62, June, 2007. Continuation. See beginning in Vol. 48, Nos. 1–2, 2007.     

State of lithium cation in a solution of polyurethane in deviethylformamide

The viscosity characteristics of solutions of PU in DMF containing different amounts of lithium chloride and perchlorate wer investigated. The dependence of the relative viscosity of the ternary systems LiX—PU—DMF on the type and content of the lithium salt was established. A hypothesis was advanced concerning the coordination of lithium cations with polyurethane functional groups. __________ Translated from Khimicheskie Volokna, No. 6, pp. 5–6, November–December, 2006.     

Basalt plastics — new materials for road construction

The effectiveness of using basalt fibres and substandard basalt wool — large-tonnage waste from chemical plants and nuclear generating stations — as a reinforcing component in road construction was demonstrated. Incorporation of basalt fibre or wool in asphalt concrete in an amount of up to 0.4 wt. % increased the strength characteristics of the asphalt concrete by 10–30%. The presence of a physicochemical reaction in the basalt fibre—polymer-asphalt binder system, which increased the strength characteristics, heat resistance, and lifetime of the polymer—asphalt—concrete, was demonstrated. IR spectroscopy showed ordering of the structure of the PAB due to formation of organosilicate compounds that strengthened the structure of the polymer asphalt concrete. Translated from Khimicheskie Volokna, No. 6, pp. 11–14, November–December, 2009.     

Localization of combustion in a periodic velocity field

A direct numerical simulation of combustion-front propagation in a specified periodic velocity field of a medium was performed within the framework of a two-dimensional thermal diffusion formulation. The calculations showed that as the velocity amplitude is increased, the flame front separates into discrete burning segments, i.e., spatial localization of the combustion takes place. Only when heat losses are introduced into the model, flame quenching is observed at a certain amplitude of the medium’s velocity. The level of heat losses required to extinguish the combustion becomes lower with increase in the amplitude of velocity perturbations. On the whole, the obtained numerical results agree with results of an asymptotic analysis. Translated fromFizika Goreniya i Vzryva, Vol. 34, No. 3, pp. 19–28, May–June 1998.     

Detonation waves in a reactive supersonic flow

A supersonic hydrogen—air flow is studied in detail, in particular, the fields of gas-dynamic parameters and chemical homogeneity of the mixture in various cross sections of the duct. The processes of excitation and propagation of a detonation wave in the downstream and upstream directions are considered. The detonation-wave velocity with respect to the mixture flow is found to differ from the nominal Chapman—Jouguet velocity for a quiescent mixture: the detonation-wave velocity is higher if the wave moves upstream and lower if the wave moves downstream. Some hypotheses on the reasons for these deviations of the experimentally measured velocity from the nominal value are given. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 5, pp. 85–100, September–October, 2006.