Modification of epoxy polymers with small additives of multiwall carbon nanotubes

The effect of small additives of functionalized multiwall carbon nanotubes used as a modifier on the formation and properties of epoxy polymers cured with diaminodiphenyl sulfone is investigated. In the range of additive concentrations 0.01–0.50 wt %, there are extreme dependences of dynamic storage modulus and the glass-transition temperature on modifier concentration. As shown by electron microscopy and X-ray scattering, regions with increased packing densities of macromolecules are formed in the polymers in the presence of the modifier. The effect of the specific surface on the kinetics of curing of epoxy resins is observed. A mechanism controlling the formation of the epoxy matrix that is responsible for the inhomogeneous polymer structuring that defines the final properties of the polymers is suggested.     

Erratum to: Combustion Dynamics of a Propane–Air Gas Mixture When it is Ignited by a Streamer Microwave Discharge

Technical Physics - erratum     

Technology for developing databases of information systems

The problem of the creation of the needed technology allowing the effective development of corporate databases is considered. As a solution, we propose a new technology based on the “object-event” semantic model and the use of the universal data model, data model language, and special database software development tools. The principal features of the proposed technology and its advantages are considered.     

Cyclophosphorylation of β-cyclodextrin silyl derivatives with trivalent phosphorus acids dichlorides

A study of cyclophosphorylation with trivalent phosphorus acids dichlorides showed that the reaction, in contrast to a similar phosphorylation with phosphorous acid di- and triamides is less effective, and in the case of phenylphosphonous dichloride is accompanied by a noticeable desilylation.     

Electromagnetic vibrator: An initiator of air breakdown in the subcritical field of a quasi-optical microwave beam

The subject of investigation is the resonance properties of cylindrical electromagnetic vibrators with different diameters and spherically rounded ends acting as initiators of air breakdown in the subcritical field of a quasi-optical microwave beam. The vibrator is placed both in the field of a traveling electromagnetic wave and at the antinode of the field above a screen inserted in the microwave beam. The shortening of the half-wave vibrator that governs its ability to initiate air breakdown, the field at the top-pole of this vibrator, and a tolerance on its resonance length are found from experimental data.     

Thermal ionization instability of an air discharge plasma in a microwave field

Results are presented from experimental studies of the initial stage of an air discharge initiated in a linearly polarized quasi-optical microwave beam. The discharge was excited at an air pressure at which the electron-neutral collision frequency in the discharge plasma was considerably higher than the circular frequency of the electromagnetic field and at a microwave field amplitude close to the threshold field for air breakdown. The experiments revealed relatively bright plasma channels stretched along the microwave electric field. The development rate of these channels and their characteristic transverse dimensions are estimated. A comparison of the experimental data and theoretical estimates indicates that the channels observed arise due to the onset of thermal ionization instability in the microwave discharge plasma.     

Microwave breakdown of air initiated by a short electromagnetic vibrator

The electrical breakdown of air (under a pressure from several tens of Torr to several hundreds of Torr) is initiated in a linearly polarized quasi-optical microwave beam using a rounded-end cylindrical metallic electromagnetic vibrator placed parallel to the electric component of the microwave field. The vibrator is much shorter than the wavelength of the field. The field strength at the top of the vibrator as a function of its length is determined. An empiric expression relating the field strength at the top with the vibrator length-to-diameter ratio is found for the vibrator length range studied. The practicability of locally measuring the field in a quasioptical microwave beam is substantiated. The idea is to determine the maximal air pressure at which electrical breakdown of air initiated by a short vibrator placed at a given point of the beam takes place.     

Division of hydrate frameworks into cavities

The algorithms for analysis of shape and size of a cavity in a hydrate framework are considered. As an example, the framework structure of cubic structure II is analyzed.     

Ignition of a Fuel Mixture Using a Multipoint Pulsed Spark Discharge under Various Initial Conditions

Technical Physics - The development of efficient and reliable ignition systems for fuel mixtures is of interest for many practical applications associated with the use of combustion power plants....