New Magnetic Polymer Nanocomposites on the Basis of Isotactic Polypropylene and Magnetite Nanoparticles for Adsorption of Ultrahigh Frequency Electromagnetic Waves

In this study, we report about the preparation of magnetic polymer nanocomposites on the basis of isotactic polypropylene and magnetite Fe₃O₄ nanoparticles. The structure and composition of polymer nanocomposite materials have been studied by scanning electron microscopy, atomic force microscopy, and X-ray dispersive analysis. The magnetic properties of polymer nanocomposites based on PP+Fe₃O₄have been investigated. It is found that not significant adhesion and agglomeration of nanoparticles occur, by increasing the nanoparticle content in polymer matrix up to 40%, and therefore they act as single-domain nanoparticles. The samples of nanocomposites based on PP+Fe₃O₄, with up to 40% content of Fe₃O₄, exhibit superparamagnetic properties. It was also found out that the magnetic polymer nanocomposite material based on PP+Fe₃O₄ is able to absorb ultrahigh frequency electromagnetic waves in the frequencies range from 0.1 to 30?GHz. The increase in Fe₃O₄ concentration from 5 to 40% at the 400?µm thicknesses of the films leads to an increase in absorption of electromagnetic waves of high frequency from 15 to 22.7%.     

Uranium Preconcentration with a Chelating Sorbent Based on Maleic Anhydride–Styrene Copolymer

The ability of a chelating sorbent based on maleic anhydride–styrene copolymer to take up uranium was studied. The sorbent was prepared by modification of the copolymer with Norsulfazolum in the presence of formaldehyde. The dependence of the sorption capacity on the solution acidity was studied. At pH 5, the degree of sorption passes through a maximum. As the uranium concentration in the solution is increased, the amount of the sorbed metal increases, reaching a maximum at a concentration of 8 × 10^–3 M (SC = 1253 mg g^–1). The influence of the solution ionic strength on the uranium sorption was examined. The ionic strength of up to 0.4 M does not affect the sorption, but as the ionic strength is increased further, the sorption decreases, first gradually and then sharply. The desorption of the sorbed uranium ions was studied. The effect of mineral and organic acids on the uranium desorption was examined. The desorption is maximal with HClO₄.     

Identification of the Parameters of a Discrete Gas-Lift Process

Journal of Computer and Systems Sciences International - A time-averaged mathematical model of a discrete gas-lift process is considered. At the first iteration, an analytical expression for the...     

The role of the polarization charges in the formation of photoluminescent properties of nanocomposites based on polyvinylidene fluoride and zirconia dioxide nanoparticles

Has been studied the effect of polarization under the influence of corona discharge on the photoluminescence properties and charge state of nanocomposites based on polyvinylidene fluoride and zirconium dioxide nanoparticles. The intensity of the photoluminescence after the polarization increases, and this increasing is concentration-depended. To clarify the reasons of the increase of luminescence intensity, the values of cumulated charges at the interface between the components of nanocomposites in the process of polarization by corona discharge have been studied by TSD method. It is shown that in the process of polarization the injected charges accumulated at the interface, and these charges create a high internal local field,where the polarization of zirconia dioxide nanoparticles occurs. Were calculated the values of the local electric field, contributing to the polarization of ZrO₂ nanoparticles. Was found that the value of the internal local field is high enough to excite new additional luminescent centers in ZrO2 nanoparticles, resulting in increased luminescence intensity. The energy activation of maximum of cross-border charge varies in the interval 0,84–1,1 eV. The thickness of the interfacial layer was calculated and found that increasing of the concentration of ZrO2 nanoparticles led to changes of the thickness of the interfacial layer in the polyvinylidene fluoride with an extremum. The maximum value of thickness observed at a concentration of 5% ZrO2 nanoparticles.     

Radiation-Induced Decomposition of Water on the BeO Surface

Radiation-induced decomposition of water in the BeO-adsorbed H₂O system at room temperature (T = 300 K) under the conditions of γ-irradiation for different times was studied by Fourier IR spectroscopy. The water adsorption onto BeO was found to occur by the molecular and dissociative mechanisms. Intermediate active products of radiation-induced heterogeneous decomposition of water, beryllium hydrides and hydroxy groups, were detected. The highest radiation-chemical yield of molecular hydrogen, G(H₂), was reached at the BeO particle size d ≤ 4 μm.

     

A study of the structure and dielectric properties of nanocomposites based on polypropylene and zirconia nanoparticles

New nanocomposite structures based on isotactic polypropylene and zirconia nanoparticles are developed; the distribution of the zirconia nanoparticles is studied by optical (Motic AE 30/31) and scanning electron microscopy (Carl Zeiss). It is shown that, during the direct introduction of nanopowders into the polymer matrix, the powder nanoparticles form cluster-like fractal structures in the form of dendrites even at the first stage of mixing of the components. The electron microscopy study of the samples shows that the developed technique for preparing nanocomposites makes it possible to obtain a homogeneous distribution of zirconia nanoparticles in the matrix of polypropylene. The dielectric characteristics of nanocomposites based on polypropylene and zirconia are studied. It is found that the dielectric permeability in PP + ZrO₂ nanocomposites varies as a function of the frequency owing to the low-frequency polarization.     

Effect of a corona discharge on the morphology and photoluminescence intensity of nanocomposites based on polypropylene (PP) and zirconia (ZrO<Subscript>2</Subscript>) nanoparticles

The effect of a corona discharge on the structure and photoluminescence properties of nanocomposites based on polypropylene (PP) and zirconia is studied. It is shown that polarization under the action of a corona discharge leads to a refinement of the structural elements and an increase in the photoluminescence intensity and the increase depends on the charge concentration. The amount of charges accumulated at the interface between the nanocomposite components is determined by the thermostimulated depolarization (TSD) method; it is found that, during polarization, a large number of electric charges accumulate at the interface between the PP and ZrO₂ nanocomposite components. It is revealed that the interfacial charges generate a fairly high internal local field, which excites luminescence centers in the zirconia and, thereby, leads to an increase in the luminescence intensity.     

Structure and properties of PP/TiO2 based polymer nanocomposites

ABSTRACT

The transient pulse testing is used in bridgewire-charges to measure the electrothermal performance non-destructively rather than by the conventional inspection. The conventional inspection has the disadvantage of destruction with a number of products tested, while the transient pulse testing can give a dynamic electrothermal curve at a user's command. In addition, the transient pulse testing can be used to measure a passel of products one by one rather than by a statistical spot check. Unfortunately, a statistic spot check cannot provide the firing reliability of products efficiently. The other way round, the transient pulse testing may put an end to the possibility of loss for users absolutely. The reason that the transient pulse testing is not devastating for products is that these mixtures of a product have a required thermal stability, and then are simultaneously able to be responded reliably by a very small pulse current. We have determined that these red matches based on Si/Pb₃O₄/DDNP mixtures electrothermal responsibility curves. Firing performance, measurements of the transient pulse testing, and electrothermal parameters are presented in this paper.     

Determination of Th(IV) in Natural Waters after Preconcentration with a Chelating Sorbent

Radiochemistry - Chelating sorbents containing norsulfazole and sulfadimezine fragments were prepared by modification of maleic anhydride-styrene copolymer with amines. The conditions of the Th(IV)...