The aim of this work was to determine the anisotropy of the electrophysical and mechanical properties of rubber reinforced with a hybrid filler CNTs&CB (carbon nanotubes and carbon black) as a function of CNT content and the technological parameters of the production process. A significant difference in electrical conductivity (σ) and dielectric permittivity (ε) in three perpendicular directions was found for CNT concentrations ranging from 0 to 0.007 in volume fraction. The highest values of σ and ε were observed in the calendering direction, with slightly lower values in the perpendicular direction. This effect was attributed to the orientation of polymer molecules and CNTs along the direction of movement during calendering, as well as the disruption of the cluster structure in the transverse direction. Although the calculated percolation threshold values of the investigated system differed slightly, a correlation was observed between the mechanical and electrophysical properties of CNTs&CB rubber. This correlation enables rubber products to be designed with optimal properties tailored to the desired direction.

This study demonstrates two novel surfactant-free methods for preparing stable hybrid dispersions: (i) oxidized graphene nanoparticles (GNPs) combined with carbon nanotubes (CNTs), and (ii) oxidized CNTs combined with GNPs. The GNP exfoliation process achieves a primary fraction (99.9% by count, ≥26% by mass) with tunable sizes (10–150 nm to 30–800 nm), controlled by exfoliation process (current density, electrolyte concentration, and suspension optical density). In Method 1, GNPs (70–150 nm) were oxidized in H2SO4 (96–98 wt%)/K2Cr2O7 (0.7 g per 2 g acid), diluted to 15% H2SO4, washed to pH 5.5, ultrasonicated (1 min), then combined with CNTs pre-dispersed in ethanol (0.5 mL). In Method 2, CNTs were anodically oxidized in 55% H2SO4 (5–30 mA/cm2, 200 A•h/kg), washed to pH 6.5–7, and dried (800°C, 20 s) before GNP incorporation. Both methods produced dispersions stable ≥3 days. The hybrid CNT@GNP dispersions were deposited onto AlSi10Mg alloy powders and polychlorotrifluoroethylene (PCTFE) via rotary evaporation. This approach facilitated uniform nanocarbon distribution, resulting in: (a) reduced electrical percolation thresholds, (b) enhanced mechanical strength at lower CNT@GNP loadings in PCTFE composites, and (c) improved processability of modified AlSi10Mg powders for 3D printing applications.

Here we disclose a method for obtaining highpurity expanded graphite (EG) with a carbon content of > 99.5% wt. from flotation-enriched graphite with a carbon content of 94-97% wt. It has been experimentally shown that this effect is produced by a combination of the synthesis process of oxidized graphite (intercalation of graphite by anodic treatment in concentrated sulfuric acid followed by hydrolysis) and chemical cleaning using solutions of ammonium bifluoride in sulfuric acid and Trilon B in an alkaline buffer as cleaning reagents. The methods of X-ray phase analysis and thermogravimetry show that the interaction of oxidized graphite with cleaning reagents does not reduce the ability to expand. The magnitude of the mass loss of oxidized graphite and the temperature range of such losses practically do not change. The main mineral impurities of graphite ore are aluminosilicates up to 60-80% wt., effectively interact with hydrofluoric acid. Iron, calcium and magnesium oxides are converted into a soluble state when interacting with Trilon B. Quantum-chemical calculations show that the Trilon B molecule is better physically sorbed on an oxidized graphenelike plane than on its native form, interaction energy (- 412 kJ/mol), (-188 kJ/mol), respectively. The interaction of Trilon B with Ca2+ and Mg2+ cations, regardless of the nature of the cation, is thermodynamically more likely in an aqueous solution than in the adsorbed state on the surface of the oxidized graphene plane. The proposed method ensures high purity of.G, which significantly reduces the cost of the technology and reduces environmental pollution.

Carbon fillers are widely used in the polymer composite materials to control electrophysical properties, which makes them promising for shielding/absorbing electromagnetic radiation in various bands, protection against radio interference and antistatic coatings, etc. The study of percolation transitions in such materials is a priority for such tasks. Epoxy resin-carbon fiber (ER-CF) and epoxy resin-carbon fiber-carbon nanotubes (ER-CF-CNT) systems with different filler contents were investigated. Electrophysical studies were carried out in the frequency range of 8–12 GHz by the non-contact method, and electrical conductivity at low frequencies of 0.1, 1 and 10 kHz was measured by the two-contact method. The bending strength was tested on a 2167 P-50 tensile tester. It was found that: the electrical conductivity at low frequencies and the complex permittivity at 9 GHz of the composites change significantly (percolation transition) in the range of 0.001–0.005 volume fraction of the combined filler; the values of the real and imaginary components of the complex dielectric constant of the composites are 50, which indicates a significant level of interaction between the components of the system and a uniform distribution of the conductive component in the composite; the maximum values of the relative flexural strength are observed at the content of CF-CNT proportional to the percolation threshold in the systems. The composites have a high level of strength at a low content of fillers, which, makes them attractive for use as protective coatings for absorbing or shielding from microwave EMFs.

The concentration set of the composites, where the micro/nano crystalline cellulose (M/NC) was used as a matrix, while multi-walled carbon nanotubes (MWCNT) were used as fillers, were prepared and studied. The dilatometric properties (relative linear thermal expansion, coefficient of the thermal expansion (CTE)), diffuse reflection spectra, photoluminescence spectra and luminescence intensity have been measured and analyzed. The band gap E-g was evaluated, so it was found that Eg value decreases (3.6 -> 3.4 eV) when the MWCNT content increases. The temperature behaviors of the relative expansion and CTE revealed two temperature ranges with different values of CTE. Noted ranges correspond to parts of the cellulose matrix with various amorphous phase structures. Nanocomposite materials under study are characterized by photoluminescence (PL), whose spectra range from soft ultraviolet to red light. The PL spectra of "pure" M/NC are formed by a complex band lying in the range 350 - 650 nm with peak position near 425 nm. When MWCNTs are incorporated into the cellulose matrix the PL intensity decreses and the spectral profile is deformed. Thus, the UV band (peak position near 330 nm) becomes the most intensive in the spectra. An appearance of the and increasing its relative intensity is considered as features of the micro/nanosized carbon fragments/clusters/dots luminescence in the cellulose matrix. Concentration dependences of the intensity and of luminescence spectra confirmed the conclusion about the selective interaction of the carbon filler with different phase components of the cellulose matrix.

Multilayer graphene nanoparticles (GNPs) have unique properties and potential for application. They are more stable compared to single-layer graphene and are suitable for mass production by splitting precursors with a graphite-like structure. The problem is not in the production of GNPs, but in the regulation of its characteristics. The application of GNPs is hindered by their agglomeration due to van der Waals interactions. To avoid this, it is necessary to create a gap between GNPs. Carbon nanotubes (CNTs) are an ideal candidate for this. CNTs can reduce internal electrical resistance and improve overall electrical conductivity. Therefore, the production of GNPs@CNTs hybrids is of interest. In work, a simple and cheap method of GNP synthesis by anodic exfoliation of expanded graphite (EG) foil in a weak alkaline electrolyte is shown. A two-level method of regulating the structure of GNPs by adjusting the nanoscale cluster structure of EG by changing the parameters of its production process and modes of “secondary intercalation”, i.e., anodic oxidation of the EG foil, is revealed. The method of synthesis of dispersions of GNPs@CNTs and film materials from them is described. The structural characteristics of GNPs, CNTs and their composites, determined by the methods of X-ray diffraction, LCS, Raman spectroscopy, XPS, DTA, TG are presented. The energetic effects of the interaction of partially oxidized graphene-like planes with each other were elucidated by the methods of quantum chemistry. It was found that the reaction between hydroxyl and aldehyde groups of two interacting graphene-like planes is thermodynamically most probable.

Composite materials based on epoxy resin filled with carbon fibers and glass fabric was produced by vacuum pressing method. The dependences of the electrophysical characteristics $(\ \varepsilon^{\ \ \prime}, \varepsilon^{\ \ \prime\prime}\,\ \sigma)$ on the content of carbon fibers in the composite was obtained. Significant change in the concentration dependences of the electrical conductivity at low frequencies, as well as the real and imaginary components of the complex permittivity at a frequency of 9 GHz of composites in the range of 0.001-0.005 of the volume fraction of CF is observed. The influence of the amount of filler in the composite on the strength characteristics was investigated. The shift of percolation threshold to the region of low values during application of filled epoxy resin to glass fabrics was found. The value of the percolation threshold in composites correlates with the filler content at which the maximum strength characteristics are achieved.

The strength characteristics of model samples of fiberglass with epoxy binder RH 285 and hardener LH 286 reinforced carbon nanotubes (CNTs) anodically oxidized and the initial, respectively, were studied. CNTs are characterized by Raman and X-ray photoelectron spectroscopy. It is shown that the oxygen content and the specific surface area of CNTs change in the opposite to the amount of transmitted electricity in the range of 30–20 A h/kg. It was found that the synergistic effect of increasing the strength occurs when the initial CNTs are added into the amine hardener by ultrasonic treatment and anodically oxidized CNTs into epoxy resin (mixing on a three-roll mixer). This effect is because the amine hardener plays the role of surfactant in relation to CNTs, orienting the carbon part to CNTs, amine outward, i.e., preventing agglomeration of CNTs. The same effect is observed for oxidized CNTs in epoxy resin (charged CNTs are repelled), and oxygen-containing groups catalyze the polymerization of epoxy resin.

Here, we explain the method of obtaining the expanded graphite-multiwall carbon nanotubes nanocomposite, give its structural and mechanical characteristics important for application, and, based on quantum chemical calculations, propose a mechanism for the formation of a chemical bond between oxidized graphene-like planes. Synthesis of expanded graphite-carbon nanotubes without binders consists in simultaneous deagglomeration of carbon nanotubes and intercalation of natural graphite. This procedure was carried out in two variants: electrochemical (anodic) oxidation and chemical oxidation. Graphite oxidized to the first stage (blue) was hydrolyzed, washed to neutral pH, dried, and heat-treated at a temperature of ~1000°C in a gas horizontal industrial furnace. The resulting expanded graphite powder was rolled on horizontal rolls. X-ray photoelectron spectroscopy was used to determine the amount of oxygen and the type of oxygen-containing groups on the surface of expanded graphite and carbon nanotubes and the dependence on the amount of electricity passed during anodic oxidation. Features of the structure of expanded graphite obtained by various methods and composite expanded graphite-multi-walled carbon nanotubes were investigated by Raman spectroscopy. The energy effects of the interaction of partially oxidized graphene-like planes with each other and their dependence on the nature of the oxygen-containing functional groups present in them and on the dimensions of the graphene-like planes themselves were clarified by quantum chemistry methods. It was established that the most thermodynamically probable is the reaction between the hydroxyl and aldehyde groups of two interacting graphene-like planes, regardless of their sizes.

The current investigation presents the results of quantum-chemical calculations (using B3LYP/6–31G(d,p) and MP2/6–31G(d,p) methods) of the interaction of the superoxide anion radical with a graphene-like plane containing various functional groups on its surface. It was established that such an interaction occurs due to the physical adsorption of the radical on the surface, and this process is significantly enhanced in the presence of ketone groups on the periphery of the cluster. The obtained data make it possible to develop highly effective antioxidants based on graphene and graphene oxide.

The book considers the patterns of formation of the structure and properties of sp2-hybridized carbon nanoformations: nanotubes (CNTs), expanded graphite (EG), graphene nanoparticles and composite materials (CM) with their participation with carbon, polymer and ceramic matrices, including EG-CNTs composite, as well as the mechanism of influence of low content of nanosized fillers on the functional and operational characteristics of the created nano-CM. It is experimentally confirmed that the mechanism of strengthening of low-filled matrices consists in creation by a grid of CNTs of layers of the matrix in a nanosized state with improved characteristics. The monograph is intended for specialists in the field of physical and chemical material science.

Every[aut]Kodrik Ivanovich, Anatoly year[aut]Nikulin Fedorovich, Alexander more[aut]Titenko Nikolaevich, Alexander than[aut]Kirchu, Fedor ~0.6 MT of[aut]Sementsov, Yurii oil[aut]Ivanenko, Kateryna is[aut]Grebel’na, Yuliia discharged[aut]Pokropivny, Alex in[aut]Vaseashta, Ashok ocean waters. Consequently, considerable amount of oil contaminantsContaminants is found in and near water surface, which have a great impact on the world ocean ecologyEcology. This chapter describes ways to clean oil and oil containing contaminantsContaminants at and near the surface of water and in events, when there is an underwater leak caused by natural fractures, leaks or mining accidents. An effective sorbentSorbent consisting of expanded graphiteExpanded graphite (EG) is proposed, which can be used as good sorbentSorbent, not only for cleaning oil pollutionPollution, but also as filter, since it has bulk density as low as 4 kg/m3, noting that and 1 g EG has specific surface ~80 m2, which binds ~80 g of oil or petrol. Physical and chemical properties of EG, as a sorbentSorbent, are analyzed in comparison with activated carbon. Furthermore, since drinking waterDrinking water supplied through corroded pipes is of poor quality, conventional filters clog quickly. Therefore, filters using EG can be used efficiently in the first stage of cleaning. Mobile equipment for producing EG onsite of accidents is described. The equipment consists of several structural units: gas supply unit, burner unit, graphite feed unit, reaction chamber, separation and output units. The reaction chamber was designed, such that a standing vortex is formed, by which there is a thermal shock and additional expansion of unopened graphite particles. Automation and simulation of the combustion process in the chamber has shown to improve the quality of EG, which reduces equipment dimensions and enhance efficiency.

The porous Co3O4 hollow nanospheres were synthesized via hard template method by a carbon spheres templated strategy. The morphology and structure of materials were studied by SEM, XRD, FTIR, BET and XPS. The structure and gas sensing properties of Co3O4 hollow nanospheres were controlled by changing the concentration of precursor and aging time. The results show that the Co3O4 hollow nanospheres with diameter of 500nm composed by 40nm Co3O4 nanoparticles can be synthesized with 0.1 mol/L precursor and aging for 48h. The surface of nanospheres is porous structure. The synthesized Co3O4 hollow nanospheres sensor have good gas response to 100 x 10(-6)-0.5 x 10(-6) NH3 at room temperature. The gas sensitivity to 100 x 10(-6) NH3 reaches 155.8% and the response time is 1.3s. The limit level of this gas sensor to NH3 is 0.5x10(-6).

The purpose of this work was to examine the interaction of graphene-like nanoclusters with fragments of polymers of the same nature, but somewhat different structure, for example, polyethylene (PE) and polypropylene (PP) by means of quantum chemistry. By method of density functional theory with the exchange-correlation functional B3LYP, the basis set 6 - 31 G (d, p) and the Grimme’s dispersion correction, the energy values have been calculated of interaction between nanocarbon fragments and oligomers of PE and PP, the most probable structures of their intermolecular complexes being optimized. A graphene-like plane of 40 carbon atoms and 16 atoms of hydrogen was chosen as a model for the surface of the graphene and carbon nanotubes (CNT). In order to take into account the dimensional effect of the surface of the nanotube fragment model on the interaction energy, in addition to the above described, two larger models were used, with the general formula C54H18 and C96N24. It has been found that the interaction energy of nanocarbon fragment with an oligomer of PP is greater, compared with PE, which is consistent with the experimental data on melting temperatures of pure polymers and nanotube-polymer composites. The polymer with a surface of nanocarbon fragment forms an intermolecular complex not bound covalently and retained by intermolecular dispersion forces. Oligomers of polymeric matters and carbon surfaces in formed nanocomplex are placed closer to each other than separate polymeric links between them.

Macroporous silicon formed by photoanodic etching with high aspect ratio and large effective surface is one of the promising materials for the development of 2D photonic structures. We fabricated nanocoatings of CdTe, ZnO, CdS surface nanocrystals and SiO2 layers on macroporous silicon surface. The near-IR optical absorption was investigated and well-separated oscillations with giant amplitude were observed in the spectral ranges of surface level absorption. This process is because of resonance electron scattering on the surface impurity states with the difference between two resonance energies equal to the Wannier-Stark ladder. Macroporous silicon structures with SiO2 nanolayers and CdS nanocrystals are proposed to enhance the photoluminescence of CdS nanoparticles with quantum yield 28%. Addition functionalization of 2D macroporous silicon is a result of the high-pressure oxidation. The structural SiO2 reorganization to orthorhombic phase increases the concentration of paramagnetic Pb centers, EPR signal amplitude and GHz radiation absorption.

We analyzed “semiconductor” model of the “polymer-CNTs” composite strengthening at 300 K and low (0.1-0.5) wt% CNTs concentration. Carbon nanotubes are among the most anisotropic materials known and have extremely high values of Young's modulus. We investigated influence of vibration bonds on polymer crystallization and strengthening in composite films of polyethylenimine, polyamide, polypropylene and rubber with multiwall carbon nanotubes. IR absorbance maxima we evaluated after formation of composite “polyethylenimine-carbon nanotube” in the spectral area of the sp3 hybridization bonds at the frequency of primary amino groups of polyethylenimine. High IR absorption in the spectral area of sp3 hybridization bonds of polypropylene, polyamide-6 with carbon nanotubes is determined by γω(CН) and γω(CH2) vibrations. We measured IR reflectance maxima of composite “rubber-carbon nanotube” in the spectral area of CH valence and deformation vibrations. The IR peak dependence on the carbon nanotube content corresponds to 1D Gaussian curve for the diffusion equation in the electric field between electrons of nanotubes and protons in polymer according to “semiconductor” model of the composite structuring. For our case of the long-acting hundreds nanometer interactions, the polymer crystallization depends on sp3 C-C bonds organization in the intrinsic electric field according to the semiconductor n-p model. Tensile strength for polyamide-6 composites at 0.25% CNTs increases 1.7 times and tensile deformation – 2.3 times.

It is given the description of expanded graphite (EG) as a cluster-assembled nanoscale system. It is shown that in the structure of EG there are both extended defects formed by the convolution of one or more graphene layers and orientation defects - disclination. The strength characteristics of EG compacted materials can be controlled by changing the parameters of the production process in a limited interval (the ratio of the amount of oxidizing agent, intercalant, with natural dispersed graphite, its particle size). The procedure for treating multiwalled carbon nanotubes (MW CNTs) with a solution of potassium dichromate in sulfuric acid was carried out according to the known technology of oxidation of natural graphite in order to obtain expandable graphite. It provides for the use of sulfuric acid as an intercalating agent and potassium dichromate (K2Cr2O7) as an oxidizing agent. The aqueous dispersion of oxidized MW CNTs is stable over time: the average particle size is 50 nm; two fractions - from 20 to 100 nm, amount - 99.9%, mass - 10%; from 250 to 500 nm and amount of 0.1%, mass - 90%; high polydispersity ranges from 0.35-0.4, that is, the particles are quite close to the spherical shape. Modification of CNTs by oxygen simultaneously with anodic oxidation of natural dispersed graphite allowed for the first time to create a carbon-carbon composite "EG – MW CNTs" with enhanced physical and mechanical characteristics without additional use of binders.

In the elements of aviation structures of large size and low rigidity rubber thermal protective coatings are used, which do not collapse when the structure is deformed. The use of rubber for supersonic aircraft and spacecraft is limited due to high requirements for heat and frost resistance of materials, as well as to their stability under the conditions of radiation and in a vacuum. Therefore, the development of new rubber with improved characteristics is an urgent problem. Multiwall carbon nanotubes are among the most anisotropic materials known and have extremely high values of Young's modulus. Carbon nanotube aspect ratio of length to diameter is more than 103; this distinguishes it from other nanoparticles. New composites with carbon nanotubes (CNTs) as additives were studied intensively during the last decade. Composites are characterized by extremely high specific strength properties, electrical and thermal conductivity. The effect of multiwalled carbon nanotubes on the performance characteristics of rubbers based on nitrile-butadiene was studied with various methods of their preliminary treatment and introduction into the composition of rubbers. It was shown that the introduction of 0.5-1.0 wt. % сarbon nanotubes into elastomers of different chemical structures leads to an increase in their physic mechanical characteristics, wear resistance and aging resistance, which significantly increases the service life of such products.

The effect of modifying the surface of multiwall carbon nanotubes (CNT’s) by oxygen and nitrogen on the strength characteristics of the fiberglass filled with them was investigated by testing for tension and bending. The method of obtaining nitrogen-containing nanostructures is developed. It was shown that in the epoxide system LR285-LH286 hydrophobic CNT’s (outgoing) at introducing into the catalyst polymerization of LH286, increase the strength with respect to unreinforced CNT’s by 48% - 54%. Oxidized CNT’s (200 A?h/kg) introduced into the resin LR285 increase the strength by 59%. The distribution of the filler particles in size, both in the epoxy resin and in the catalyst, depends on their concentration nonlinear, and correlates with the strength characteristics of the composite.