Graphite oxide synthesis dynamics were investigated using a sampling technique. The synthesis of graphite oxide was carried out by a modified Hummers' method. Small samples of the solid phase (30-50 mg) were collected from the reaction mixture and analyzed by thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The strongest oxidation was detected 10 min after the start of the synthesis, i.e., after the addition of KMnO4, when the formation of the graphite oxide phase with intercalated guest molecules begins. The intercalation of graphite started after 30 min of synthesis when the temperature was increased to 35 degrees C. The addition of ice into the reaction mixture leads to the increase in the COOH group concentration, whereas the concentration of C=O groups slightly changes, and the concentration of the C-O and C=O groups remains almost constant. It was found that the degree of oxidation of graphite oxide exhibited complex change, and H2O2 plays a significant role not only in the removal of impurities but also in the increase in the GO oxidation degree that is reflected by a higher concentration of oxygen-containing functional groups. Differential scanning calorimetry and thermogravimetric analysis data confirmed that the additions of ice and H2O2 induce the stronger formation of surface functional groups instead of intercalated guest species.

The present study is devoted to ultrasonication of exfoliated graphite in different organic solvents (dimethyl sulfoxide, propanol-2, and chloroform). Graphite nanoplatelets are obtained as a result of strong acoustic treatment (10 W/cm(3)). The obtained samples are investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, low-temperature nitrogen adsorption, FTIR and Raman spectroscopies. It is found that the structural and texture characteristics of the obtained materials significantly depend on the type of a solvent.

A method of measuring the velocity of Hilbert-visualized phase structures by means of emulation of two-dimensional spatial filtering of their images formed on the matrix of a digital camcoder is discussed. As an example, visualized fields of the phase optical density in convective flows induced in a high-viscosity fluid are considered. Investigations of this kind of flows are useful for simulating the Earth’s mantle behavior at large depths.

In this work, the epoxy resin/carbon nanofiller composites were obtained and their properties were investigated. It was shown that electret characteristics changed during addition of heat treated multi-walled carbon nanotubes: the low filler loading decreased the surface potential, effective surface charge density and electric field strength of the samples. Increasing the filler loading higher than 0.8 wt. % induced the recovery of epoxy polymer electret characteristics. Increase of mechanical properties arisen due to transition of epoxy composites to electret state were found to be the result of orientation of polar groups of epoxy polymer, occurring during the polarization.

Thermal degradation of epoxy composites filled with various carbon materials (thermally expanded graphite, multiwalled carbon nanotubes) was studied. The dynamics of the thermal degradation of epoxy composites was evaluated by thermogravimetric analysis in the temperature range of 55–700°С (heating rate 10 deg min–1) in an oxidizing medium. Carbon fillers were studied by scanning electron microscopy, transmission electron microscopy, and low-temperature nitrogen adsorption. The influence of the composite preparation procedure on its thermal stability was determined. The type of filler significantly influences the thermal oxidative degradation of the composites.

Effect of synthesis parameters on the characteristics of expanded graphite were studied. The starting sample, intercalated graphite, was treated by several methods: thermal shock (400, 1000°C) and programmed heating (400–700°C). The samples were examined by scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction analysis, and low-temperature nitrogen adsorption. The programmed-heating method yields better texture characteristics as compared with the thermal shock. The programmed-heating method was used to obtain high-quality expanded graphite with high specific surface area (299 m2 g–1) at a comparatively moderate temperature of 400°C.

The sensing properties of carbon nanomaterials are studied and compared in this paper. Graphene oxide and multi-walled carbon nanotube films were used as active layers of chemo-resistive gas sensors and characterized at room temperature towards ammonia detection in concentration levels from 100 ppm to 500 ppm in air. We conclude that graphene oxide based sensor has higher response (2.4% to 7.4% in range from 100 ppm to 500 ppm) than the multi-walled carbon nanotubes based one (1.0-2.4%). On the other hand, the carbon nanotubes based sensor possessed higher recovery rates in a wide range of used concentrations.

This paper presents results of numerical modeling of energy separation for helium-xenon gas mixture flow in a two-cascade Leontiev tube with central and outer (annular) supersonic nozzles. The Mach number and stagnation temperature distributions in longitudinal section and the heat-transfer intensity from the subsonic to supersonic flow have been obtained. The dependences of the cooling effect, the temperature efficiency factor and the adiabatic efficiency on a stagnation pressure in the receiver have been investigated.

In this paper the results of experimental and theoretical investigation of heat and mass transfer with adiabatic evaporation of bicomponent water/ethanol fluid to an air flow are presented. An innovative test section for the wind tunnel with an active thermal stabilization system, maintaining the cuvette temperature equal to the evaporation surface temperature, is used to provide the evaporation adiabatic conditions. The wall temperature obtained experimentally shows the presence of expressed quasi-stationary evaporation area, qualitatively similar to sublimation curves of volatile organometallic compounds. A theoretical model based on the similarity of heat and mass transfer processes for each of the evaporating solution component is suggested. This model allows to determine evaporation surface temperature (sublimation temperature) accounting for radiation effect.

Graphite nanoplatelets treated with nitric acid of different concentrations were studied. The initial graphite nanoplatelets were prepared by ultrasonication of exfoliated graphite. The samples were examined by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and FTIR and Raman spectroscopy and were tested as electrode materials for supercapacitors.