This work studied the role of the iron oxide and MWCNT in a change of the electrophysical properties of PP + Fe3O4 + MWCNT nanocomposite to evaluate the potential of these nanocomposites as magnetic field sensors and EMI materials. The morphology of the obtained nanocomposites was studied with a scanning electron microscope and investigated that the sizes of both magnetite nanoparticles and carbon nanotubes stay stable during the three-phase nanocomposite formation. In addition, the X-ray diffraction method revealed that MWCNT plays an essential role in the ordered structure-formation of a polymer nanocomposite more than iron oxide nanoparticles. Dielectric properties of the PP + Fe3O4 nanocomposite were studied. Both dielectric permeability and dielectric losses of PP+MWCNT+Fe3O4 nanocomposites were enhanced. The dielectric permeability of the nanocomposite increased due to the interphase polarization, which in turn related to the formation of ordered structure caused the partial arrangement of carbon nanotubes in the polymer. Furthermore, the study showed that the negative magnetoresistance effect of PP+MWCNT+Fe3O4 nanocomposites is more dependent on the amount of Fe3O4 nanoparticles than that of MWCNT, which explained by the spin polarization of Fe3O4 nanoparticles at room temperature. In this research, the PP+5%Fe3O4+1%MWCNT nanocomposites were considered to be an effective material for magnetic field sensors and EMI shielding.

The aim of this research is investigation of FeNi bimetallic nanoparticles effectiveness after their using in the reduction of the high nitrate concentration. The advantage of the reusability is opportunity to create cost effective and environmentally friendly technologies. In this paper the efficiency of the same bimetallic nanoparticles was described. The same nanoparticles were used for nitrate reduction in the first, second and third times. After each use they were collected and used again for reduction of 300 mg L −1 nitrates. Fe/Ni based bimetallic nanoparticles were synthesized freshly and used for nitrate removal. Synthesis of bimetallic nanoparticles was carried out in the presence of sodium oleate as dispersing agent by widely known borohydride reduction method. Batch experiments were performed on nitrate contaminated water samples. The parameters investigated were the reaction pH (acidic, alkaline conditions) and nitrates concentration after their reusing. The results showed that the total nitrate reduction (99.75%) was occurred after 5 min of reaction in the presence of freshly synthesized nanoparticles. Then the same nanoparticles were repeatedly used for nitrate reduction. This test has been performed thrice to study nanoparticles effectiveness after each use. It was investigated that the efficiency of nitrate degradation decreased after reusing. The second remediation by the same nanoparticles consisted 64.67% of nitrates removal and the third one – 47%. To evaluate the nitrate reduction rate and the kinetic of reaction, additional tests were performed at different temperatures. The structural characterization of freshly synthesized and reused bimetallic nanoparticles was investigated by TEM. Results showed that bimetallic nanoparticles were covered with an oxide layer after nitrates reduction. Decreased efficiency of reused bimetallic nanoparticles can be due to the appearance of an oxide layer.

The structure and optic properties of the transparent PP+SiO2 nanocomposites with a relatively high refractive index and enhanced luminescence properties were investigated. X-ray analysis, Fourier-transform infrared (FTIR), Visible-ultraviolet, and photoluminescence spectroscopic methods were used for investigation. The XRD analysis indicated that the fraction of the amorphous phase of the polycrystalline polymer decreases with the introduction of SiO2 nanoparticles. Even though SiO2 nanoparticle is amorphous itself, they play the role of the crystallinity centers in the polymer matrix, and the degree of crystallinity increases in polymer nanocomposites. According to UV-vis spectroscopic analysis that, with the increasing of the concentration of SiO2 nanoparticles distributed in the polymer matrix, the absorption intensity of the samples also increases. It was explained by the hyperchromic effect which is related to raising the optical density of the polymer by introducing the filler particles (SiO2). It was calculated bandgap energy and refractive index on the base of the UV spectra of samples. It has been found that at low concentrations of amorphous silica nanoparticles, the polymer nanocomposite retains its transparency despite having a relatively high refractive index (1.96). Furthermore, the photoluminescence (PL) spectrum of nanocomposites was investigated depending on filler concentration. It was clear that the intensity of the PL spectrums increases with the increase of the filler concentration that is explained by the raising of the luminescence centers in the nanocomposite material. These luminescence centers are oxygen-deficit centers in the spatial structure of the amorphous silica nanoparticles.

Combined hybrid nanocomposites based on PVDF+CdS/ZnS were developed and studied. The structure of nanocomposites was characterized by XRD, SEM, EDS, UV-spectroscopic techniques. XRD analysis shows that the incorporation of CdS and ZnS semiconductor nanoparticles leads to a decrease in the fraction of the a-phase and an increase in the beta-phase of the polymer. It was determined that the bandgap of the nanocomposite based on PVDF+1%CdS/ZnS, PVDF +3%CdS/ZnS, PVDF+5%CdS/ZnS and PVDF+10%CdS/ZnS is 5.3 eV, 5.0 eV, 4.3 eV and 3.1 eV, respectively. The photoluminescence properties of the polymer nanocomposites were also examined. It was established that for these nanocomposites, the introduction of the CdS/ZnS nanoparticles into the polymer matrix leads to expanding of the spectral-sensitive region of the PL spectrum of the nano-composites. It was shown that combine hybrid nanocomposites on the base of PVDF+CdS/ZnS emit the light at the wide-wavelength-range. According to this feature, it is possible to use these nanocomposites in various fields of optoelectronics as the active elements of solar batteries, cells, displays, converters, etc. The photosensitivity of the PVDF+CdS/ZnS films was discovered. It gives the possibility to use these materials as thermoplastic photoresistors. [GRAPHICS] .

In this study, the influence of electro-thermo-polarization (ETP) on the charge state and luminescence properties of polymer nanocomposites based on PP and nanoparticles of amorphous silicon dioxide nanoparticles were investigated. By comparing the results of the charge state and the intensity of the PL spectra of nanocomposites, it was determined that polarized composites with a 3% mass content of SiO2 nanoparticles have relatively high luminescence. For the same composites PP + 3% SiO2, relatively high values of the spatial space charge density, the intensity of the internal local field, and the thickness of the interphase layer are observed. Space charges create a large internal local field that stimulates the already existing oxygen deficiency centers in amorphous silica nanoparticles. This leads to the activation of the luminescence centers, which is the cause of the increase in the PL emission intensity in this nanocomposite after the ETP.

In this study have been prepared optically transparent polymeric nanocomposites based on PP/YSZ by combination of ex-situ and hot pressing methods. The structure of the synthesized nanocomposites was studied by XRD analysis, UV spectroscopy, scanning electron microscopy. The optical and photoluminescent (PL) properties of polymer nanocomposites were investigated. It was found that with an increase in the concentration of YSZ nanoparticles in the PP matrix to 3% of the content of nanoparticles, the PL intensity increases, with a further increase in the nanoparticles content, the PL intensity decreases. This is explained by the fact that with an increase in the concentration of YSZ nanoparticles, their size increases and their specific surface decreases, and this leads to a decrease in the contacting region between the polymer and the nanoparticle. A decrease in the interphase boundary leads to a decrease in interphase interactions, and this in turn leads to a change in the PL intensity. It was also shown that the PL intensity for nanocomposites at all wavelengths increases with increasing annealing temperature to 120°C, and then decreases. Possible reasons for a significant increase in the PL intensity after thermal annealing are the redistribution of charge carriers between levels in the band gap or the recharging of recombination centers and the removal of organic compounds adsorbed on the surface of nanocomposites.

Electrochemical obtaining of nano-coatings in the system Re-Cu-Se on platinum electrode during voltammetric cycling was studied. The research was carried out using sulphate solution containing selenium dioxide, potassium perrenate and copper chloride. For obtaining nano coatings in the Re-Cu-Se system, we used an electrolyte of the following composition (mol/l): 6.9 ∙ 10-4 – 6.9 ∙ 10-3 KReO4 + 9 ∙ 10-4 – 1.8 ∙ 10-2 SeO2 + 6 ∙ 10-4 – 1.2 ∙ 10-2 CuCl2 ∙ 2H2O +2 H2SO4, t = 80 ºC; V = 0.005VS-1; pH = 0.1, electrode - Pt. Based on the studying of the volt-ampere dependences during the joint electroreduction of rhenium (VII), selenium (IV) and copper (II) ions from sulfate electrolytes on a PT electrode, the conditions for the deposition of alloys nanocoatings in the Re-Cu-Se system were established. To study the morphology of films on platinum and copper substrates, the electrode surface was studied using a JEOL JSM7600F scanning electron microscope at various magnifications, and was accordingly subjected to elemental analysis using an Oxford X-MAX 50 detector. The sample has been scanned in the mode of secondary electrons at an accelerating voltage ~ 15 keV. It has been found that agglomerates are observed on the electrode surface, mainly consisting of sphere-shaped particles with an average size of ~ 20-25 nm. The spectrum of characteristic X-ray radiation indicates the presence of these components of the system, allows quantitative analysis of samples. Based on the presented distribution diagram by weight percent, the content of system components is represented by the following ratio: Re-12%, Cu-5%, Se-10%. The presence of characteristic peaks of carbon and oxygen in the spectrum is explained by residual phenomena during obtaining.

PP + ZrO2 polymer nanocomposites obtained through different temperature-time modes of crystallization and exposed to electrothermopolarization were studied in this paper. Even though the preparation method of nanocomposite samples was the same, their lifetimes and surface charge density were different. It was investigated that nanocomposite obtained by slow-cooling (SC) conditions has high stability but low surface charge density. It was also revealed that the dependence of relaxation time of the electret state on the percentage content of filler has a nonmonotonic character. The change of the thickness of the interphase layer of nanocomposite depending on cooling rate is explained by the change of the supramolecular structure of the polymer and the interphase interaction among the components of the nanocomposite. It was considered that the change of the thickness of the interphase layer of the nanocomposite depending on the intensity of the electric field during electrothermopolarization due to the difference in charge accumulation during the polarization process.

In the given paper were investigated photoluminescence properties of PVDF/PbS/CdS hybrid nanocomposites after thermal treatment at different temperatures (100 degrees C, 120 degrees C and 140 degrees C) under the vacuum. The optical band gap was calculated on the basis of the spectra of UV absorption and it was shown that after thermal treatment the nanocomposites optical band gap changed. The change has been attributed to the modification of the upper molecular structure of the polymer matrix due to the thermal process. The luminescence spectra of nanocomposites before and after thermal treatment at different temperatures (100 degrees C, 120 degrees C and 140 degrees C) under vacuum were also measured and discussed. It was found that the reduction of the luminescence spectra of nanocomposites after thermal treatment at high temperatures is due to the increase of the intermolecular interactions between the nanoparticles and the matrix due to the removal of the solvent from the polymer and the change in the polymeric structure.

Ag2S/ZnS nanocomposites were synthesized using a novel method, and their structural features and optical properties were also investigated. For the structural investigation of the core/shell-like nanocomposites, X-ray powder diffraction technique (XRD) and scanning electron microscopy (SEM) were used. Optical features of Ag2S/ZnS nanocomposites were studied by UV-Vis absorption and photoluminescence spectroscopy (PL). According to the SEM images, the sizes of the Ag2S, ZnS nanoparticles and Ag2S/ZnS core/shell-like nanocomposites are in the region of the 10-15; 25-50 and 15-80 nm, respectively. Furthermore, the absorption spectroscopy indicates that the bandgap of Ag2S/ZnS nanocomposites is approximately 2.4 eV. By comparison of the intensities of the emission spectra, it was clear that the intensity of Ag2S/ZnS is much lower than that of ZnS.

Poly(vinyl chloride) (PVC)–cadmium sulfide (CdS) nanocomposite films were successfully synthesized by ex situ solution casting method. Scanning electron microscopy showed that CdS nanoparticles are well monodispersed in the PVC matrix. From the ultraviolet (UV) spectra of nanocomposites, the width of the forbidden band for polymer nanocomposites was determined by extrapolation method. UV-visible optical spectra revealed that the optical band of nanocomposites is increased with increasing concentration of CdS nanoparticles in the PVC matrix. It was found that the band gap is 3.8 eV for PVC-3% CdS nanocomposites, 2.7 eV for PVC-5% CdS, and 2.35 eV for PVC-10% CdS nanocomposites. Photoluminescence spectrum of PVC-CdS-based nanocomposites shows two luminescent peaks at the wavelengths of 436 nm and 472 nm at the luminescence spectrum which belongs to CdS nanoparticles. Photoluminescence study shows that PVC-CdS nanocomposites exhibit a great blue shift (approximately 100 nm) compared with bulk CdS nanoparticles.

The tendency to improve the properties of insulating materials by incorporating inorganic nanoparticles has become necessary in order to design new insulation systems. In this study, PVC/TiO2-based nanocomposites with different loadings (3, 5 and 10 wt.%) of TiO2 nanoparticles were prepared by the solution mixing method. The morphology of the prepared nanocomposites was studied by Atomic Force Microscope (AFM). Experimentally, it was found that as the concentration increases, the size of the surface structural elements and particle size increases. Photoluminescence (PL) analysis of samples shows improvement compared to the pristine polymer. Furthermore, PL intensity for nanocomposites increases depending on the concentration and saturation occurs at a certain amount of titanium dioxide nanoparticles. The increase in luminescence intensity till a certain nanoparticle content is due to the growth of the luminescent surface area. Further saturation is explained by the increase in particle size with no increase or a slight reduction in surface area. Dielectric properties of nanocomposites were studied. It was found that dielectric permittivity of the materials increases as the nanoparticle volume content increases and it reaches at its highest value for the nanocomposites with 3% nanoparticle content. The optical properties of the polymer and nanocomposite films were studied in the region 200 nm to 600 nm. It was found that the PVC/TiO2 nanocomposites showed enhancement in the absorbance intensities which was more significant for the nanocomposites with higher nanoparticle content compared to the pristine polymer. Furthermore, absorption spectra were used to calculate the optical bandgap of the prepared nanocomposite films and red-shift observed in the calculated values of bandgap for nanocomposites. Consequently, it was proved that by incorporating TiO2 nanoparticles into the polymer matrix, the spectral region of the samples can be expanded resulting in broadened application of such systems in various fields of science and technology.

In this study, the production and the EM-wave absorption properties of the polymer nanocomposites were investigated. The two- and three-phase polymer nanocomposites on the base of the PVDF matrix, multi-walled carbon nanotubes, and magnetite nanoparticles were produced by the in-situ method. With the help of XRD and SEM methods, produced nanocomposites were analyzed. Measurement of the absorption coefficient of the nanocomposites with different filler concentrations shows that the maximum effect was obtained for the nanocomposite, with 20 wt% of MWCNT in the PVDF matrix. Very close value to maximum was also, got for a nanocomposite, which contained 10 wt% of MWCNT and 5 wt% of Fe(3)O(4)in the PVDF matrix. These results were related to energy dissipation at the high-frequency region, depending on the components fraction in the nanocomposites.

Inorganic filler and polymer matrix based PP + SiO(2)nanocomposites have been prepared by the hot pressing method. The scanning electron microscopy (SEM) and X-ray diffractometer(XRD) were used for structure investigation. It was found that the average size of the nanoparticles is around 50 nm. Photoluminescence properties of PP + SiO(2)nanocomposite and the effect of concentration of the SiO(2)nanofiller on dielectric and electrical dispersion behavior of the nanocomposite have been investigated. Besides, it was shown that the dielectric permittivity of PP + SiO(2)nanocomposite samples was gradually increased with raising filler content. Furthermore, it was observed a significant decreasing in the values of the epsilon ' and delta parameters of the nanocomposites in the 10(3)-10(6)Hs frequency range for all concentrations of filler. This decrease perhaps associated with the interphase polarization of the PP + SiO(2)nanocomposites. It was also shown that PP + SiO(2)nanocomposite demonstrates wide-band photoluminescence in visible region (400-700nm) when the excitation wavelength is 370 nm. This is due to the defects of SiO(2)nanoparticles embedded in the polymer matrix, and more precisely, with presence of oxygen-deficiency centers.

There have been investigated dielectric properties of PP + ZrO(2)based nanocomposites after exposure to an external electric field. It is shown that beforeE = 10 center dot 10(6) kV/m the dielectric constant (epsilon'), dielectric-loss tangent (tg phi) and specific resistance (lg rho) increase but subsequent increase of electrothermal treatment (ETP) brings about the decrease of magnitude like these. It is expected that the decrease of epsilon', tg phi and lg rho of nanocompositions with the frequency rise is related to the polarization process retardation. At high-frequency values, the change of given parameters appears to be related to the destruction of hole centers and change of stationary charges in polymer near-surface layers.

In the present study, the effect of magnetite (Fe3O4) nanoparticles on the structural and dielectric properties of poly(vinylidene fluoride) (PVDF) matrix was investigated. Distribution of Fe3O4 nanoparticles in the polymer matrix has been studied by scanning electron microscopy (JEOL JSM-7600 F). The structure of the nanocomposite samples was investigated by the X-ray diffraction and Fourier-transform infrared spectroscopy. It was shown that the dielectric permittivity of PVDF + Fe3O4 nanocomposite samples was gradually increased up to 7 wt% of Fe3O4 content. Further increase in the concentration of the filler leads to decrease in the dielectric permittivity. The subsequent decrease in dielectric permittivity at higher Fe3O4 content can be explained by the increase in defects in the structure of the nanocomposite. The comparison of experimental data and the results of theoretical calculations show that the reduction in the empirical value of dielectric permittivity of the nanocomposite is obviously linked with the threshold value of filler. While calculating the theoretical value of the dielectric permittivity for the higher content of the filler, defects in the nanocomposite structure should be considered.

A PP+Fe nanocomposite's phase identification, morphology, nanoscale imaging and magnetic structure have been determined with the use of the X-ray diffraction, scanning electron microscopy, atomic force microscopy and magnetic force microscopy techniques, respectively.In a polymer matrix, iron nanoparticles are found to be randomly distributed and their distribution was described by the log-normal function.The theoretically determined dependence of the particles' size on concentration showed good agreement with the scanning electron microscopy results.The present study showed that the magnetic and geometric sizes of Fe nanoparticles in the polymer matrix differ from each other.Additionally, the magnetic size of the Fe nanoparticles of the identical geometric size decreases with increasing filler concentration in the polymer matrix.The increase of Fe nanoparticles' concentration presumably leads to oxidation of the surface layer which is likely non-magnetic.The magnetic behaviour of the PP+Fe nanocomposite depending on iron content was investigated both theoretically and experimentally.The results of the magnetic measurement indicated the presence of a natural oxide layer in addition to pure iron.The comparison of the theoretical curve of M (H) with that of the magnetic measurement clearly showed that the obtained curves share the same qualitative feature.In both cases, for all concentrations of the nanoparticles, an open hysteresis loop characteristic for multi-domain particles was observed.The qualitative difference between the experiment and theoretical calculations was explained by the influence of several factors including the microstructure of the medium and the magnetic domain structure of the iron nanoparticles in the polymer matrix.

PP + Fe3O4 nanocomposite films were produced by two technological ways, namely hot pressing and extrusion techniques. It was found that depending on the production methods, the proportion of absorbed EM waves by the composite films differs. It is known that the EM waves absorbing properties of materials depend on the electrophysical parameters. Therefore, the frequency dependence of dielectric permittivity and dielectric loss were investigated for both type samples. The polarization properties and the frequency dependence of the dielectric losses of the nanocomposites obtained by different methods vary both quantitatively and qualitatively. It was also studied the influence of an external permanent magnetic field on the electrical resistivity of the nanocomposite samples. It was found that independent of the production techniques the electric resistivity of both polymer nanocomposite samples decreases under the influence of an external magnetic field, and the negative magnetoresistive effect was observed. The proportions of EM waves absorption and also differentiation of other electrophysical properties of these nanocomposites, which consist on same components but were produced throughout different methods, could be explained by the fact that the diamagnetic anisotropy, defects density and also interphase layer on the boundary of nanoparticles and matrix in these materials are quite different from each other.

Copper nanoparticles via chemical reduction of copper sulfate by sodium borohydride in the presence of sodium oleate stabilizing agent have been synthesized and stabilized. X-ray phase analysis has shown that the synthesized nanoparticles in the core consist of metal nanoparticles and the surface is covered with a shell of copper oxide. SEM analysis of nanoparticles stabilized in the presence of sodium oleate showed that copper nanoparticles, coated with the shell of copper oxide, have a narrow particle size range of 14-25 nm. Polymer nanocomposites based on PP/Cu-CuO were obtained by the combining of ex-situ casting solution and hot pressing methods. The structure and electrophysical properties of polymer nanocomposites were investigated. Have been established that at lower concentrations, nanoparticles play the role of structurant, as a result the new polar groups and stable charge-trappings are created in the obtained nanocomposites, which in turn increases the value of dielectric permittivity of nanocomposites and enhances the polarizability of these materials.