The objective of this work is to study the peculiarities of structural organization, morphology, thermomechanical, electrical and antimicrobial properties of nanocomposites based on pectinpolyethyleneimine interpolyelectrolyte complexes and silver nanoparticles in dependence on the type of reducing agent being applied for chemical reduction of silver ions in the interpolyelectrolyte-metal complexes. The average size of Ag nanoparticles is shown to be increased with decreasing of the activity of reducing agent (E 0 ) and equals to 3.8 nm, 4.3 nm, and 15.8 nm, respectively, when engaging sodium borohydride (-1.24 V), hydrazine (-1.15 V) and ascorbic acid (-0.35 V). Moreover, it was found that the crystallite size of Ag nanoparticles also had the smallest value for nanocomposites obtained involving NaBH 4 as reducing agent. Ag-containing nanocomposites prepared by reduction of silver ions in interpolyelectrolyte-metal complexes while applying a range of reducing agents are characterized by different electrical properties and polymer matrix' glass transition temperature. The influence of silver nanoparticles' size incorporated in the polymer matrix on the antimicrobial activity of nanocomposites has been established. The inhibition zone diameter of Staphylococcus aureus and Escherichia coli was higher for nanocomposites obtained using sodium borohydride and hydrazine compared to nanocomposites where ascorbic acid was used as the reducing agent.

Equation of convective diffusion of ionized metal vapour in arc plasma, allowing for the difference in coefficients of diffusion of atoms, single-and double-charged metal ions, presence of thermodiffusion flows of metal particles, as well as ion drift in the electric field, was proposed to more precisely define the earlier developed complex model of the processes of energy, mass and charge transfer in the column and anode region of electric arc with refractory cathode and evaporating anode, running in inert gas. Based on the thus precised complex mathematical model, numerical analysis of the influence of diffusion-induced evaporation of anode material (Fe) on heat, gas-dynamic and electromagnetic characteristics of multicomponent plasma of the column and anode region of stationary electric arc with refractory cathode (W) at its running in inert gas (Ar) was performed. An essential influence of metal surface temperature distribution in the region of anode binding of the arc on distribution of temperature and electric current density in near-anode plasma, as well as on distributed and integral characteristics of its thermal impact on evaporating anode surface, is shown. 18 Ref., 12 Figures. K e y w o r d s : electric arc, refractory cathode, evaporating anode, arc column, anode region, multicomponent plasma, metal vapour, diffusion, mathematical simulationElectric arc plasma in inert-gas nonconsumableelectrode welding, as a rule, is multicomponent, as alongside shielding gas particles, it contains atoms and ions of metal vapour coming to the arc gap due to evaporation of anode metal from weld pool surface. Presence of an even small amount of metal component in inert gas arc plasma has an essential influence on its ionization composition, thermodynamic, transport and optical properties. It leads to a significant difference of heat, electromagnetic and gas-dynamic characteristics of plasma in near-anode zone of arc column in nonconsumable-electrode welding from respective characteristics of arc discharge with refractory cathode and nonevaporating, for instance, water-cooled anode. Characteristics of welding arc anode region, determining the conditions of thermal and electromagnetic interaction of the arc with metal being welded and, consequently, nature of its penetration, are also different [1].In the first publications, devoted to mathematical simulation of the processes of heat, mass and charge transfer in refractory cathode arcs [2-10], arc plasma was assumed to be single-component, i.e. containing atoms and ions of just the shielding gas. Such idealization did not incorporate any conditions of running of real welding arcs, and required further improvement of mathematical models of the arc, in order to allow for a number of additional physical factors, related to multicomponent nature of arc plasma. Publications devoted to allowing for evaporation of anode material in simulation of nonconsumableelectrode welding arc, appeared in the world scientific literature comparatively recently [11][12][13]. When describing...

The article is concerned with hybrid amorphous polymers synthesized basing on epoxy oligomer of diglycide aliphatic ester of polyethylene glycol that was cured by polyethylene polyamine and lithium perchlorate salt. Structural peculiarities of organic-inorganic polymer composites were studied by differential scanning calorimetry, wide-angle X-ray spectra, infrared spectroscopic, scanning electron microscopy, elemental analysis, and transmission and reflective optical microscopy. On the one hand, the results showed that the introduction of LiClO4 salt into epoxy polymer leads to formation of the coordinative metal-polymer complexes of donor-acceptor type between central Li+ ion and ligand. On the other hand, the appearance of amorphous microinclusions, probably of inorganic nature, was also found.

As it is known, polyethylene (PE) is one of the common materials in the modern world, and PE products take the major share on industrial and trade markets. For example, various types of technical PE like PE-63, PE-80, and PE-100 have wide industrial applications, i.e., in construction, for pipeline systems etc. A rapid development of plastics industry outstrips detailed investigation of welding processes and welds’ formation mechanism, so they remain unexplored. There is still no final answer to the question how weld’s microstructure forms. Such conditions limit our way to the understanding of the problem and, respectively, prevent scientific approaches to the welding of more complicated (from chemical point of view) types of polymers than PE. Taking into account state-of-the-art, the article presents results of complex studies of PE weld, its structure, thermophysical and operational characteristics, analysis of these results, and basing on that some hypotheses of welded joint and weld structure formation. It is shown that welding of dissimilar types of polyethylene, like PE-80 and PE-100, leads to the formation of better-ordered crystallites, restructuring the crystalline phase, and amorphous areas with internal stresses in the welding zone.

A mathmatical model of electromagnetic processes occurring in the 'arc column -anode regionevaporating anode' system is presented. The anode region of electric arc with an evaporating metallic anode is described by a model, under which the non-equilibrium near anode plasma containing atoms and ions of the evaporated metal, along with atoms and ions of the ambient (inert) gas, is subdivided into a space charge layer immediately adjoining the anode surface and ionisation region adjacent to the arc column. This model allows determining the potential drop between welding arc column plasma and anode surface depending on the current density and plasma temperature near the anode, as well as upon the temperature of its surface.

A simple analytical model of binary alloy anode evaporation in gas–tungsten arc and gas–metal arc welding is proposed. The model comprises the model of evaporation in convective and diffusive regimes, model of anode processes and allows one to calculate basic physical properties of multicomponent arc plasma near the anode surface as functions of the anode surface temperature, anode chemical composition, electron temperature and electric current density at the anode surface. Evaporation of binary Al–Mg alloys with different magnesium mass fraction into argon plasma is considered on the basis of the proposed model. The dependences of the alloy boiling temperature on the magnesium mass fraction and electron temperature are presented. Several physical parameters, which are important from the technological point of view (magnesium mass flux, heat loss due to evaporation, anode potential drop, anode heat flux), are calculated for a wide range of anode surface temperature and different values of the magnesium mass fraction. In addition, the influence of heat loss due to evaporation on the total heat flux coming to the anode surface is demonstrated.

In the present work, ion-conductive hybrid organic-inorganic polymers based on epoxy oligomer of diglycide aliphatic ester of polyethylene glycol (DEG) and lithium perchlorate (LiClO4) were synthesized. The effect of LiClO4 content on the electrophysical properties of epoxy polymers has been studied by differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS). The effect of LiClO4 content on the structure has been studied by wide-angle X-ray scattering (WAXS). It was found that LiClO4 impacts on the structure of the synthesized hybrid epoxy polymers, probably, by formation of coordinative complexes {ether oxygen-lithium cations-ether oxygen} as evidenced from a significant increase in their glass transition temperatures with increasing LiClO4 concentration and WAXS studies. The presence of ether oxygen in DEG macromolecules provides a transfer mechanism of the lithium cations with the ether oxygen similar to polyethylene oxide (PEO). Thus, the obtained hybrid polymers have high values of ionic conductivity σ' (approximately 10−3 S/cm) and permittivity ϵ' (6 × 105) at elevated temperatures (200°С). On the other hand, DEG has higher heat resistance compared to PEO that makes these systems perspective as solid polymer electrolytes able to operate at high temperature.PACS81.07.Pr; 62.23.St; 66.30.hk

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