Olga B. Nazarenko

Thermal Degradation of Polymer Blends, Composites and Nanocomposites

This chapter deals with a brief account of thermal degradation of polymer-based blends, composites and nanocomposites. Different synthesising, preparation and characterisation methods of thermal degradation of polymer-based blends, composites and nanocomposites are discussed. Finally the applications, new challenges and opportunities for these thermal degradation of polymer-based blends, composites and nanocomposites are discussed.

Electroexplosive Technology of Nanopowders Production: Current Status and Future Prospects

The current situation of the nanopowders production technology based on the process of electrical explosion of wires is described. The advantages and disadvantages of the electroexplosive technology are indicated. The results of studies characterizing the effect of the electrical explosion conditions on the nanopowders properties are presented, including latest results: conditions of nanopowders passivation, conditions of nanopowders production having narrow size distribution, the methods of nanopowders diagnostic and standartization. In addition, the application and area of future research on this technology are proposed.

Thermal and Mechanical Characteristics of Polymer Composites Based on Epoxy Resin, Aluminium Nanopowders and Boric Acid

The epoxy polymers are characterized by low thermal stability and high flammability. Nanoparticles are considered to be effective fillers of polymer composites for improving their thermal and functional properties. In this work, the epoxy composites were prepared using epoxy resin ED-20, polyethylene polyamine as a hardener, aluminum nanopowder and boric acid fine powder as flame-retardant filler. The thermal characteristics of the obtained samples were studied using thermogravimetric analysis and differential scanning calorimetry. The mechanical characteristics of epoxy composites were also studied. It was found that an addition of all fillers enhances the thermal stability and mechanical characteristics of the epoxy composites. The best thermal stability showed the epoxy composite filled with boric acid. The highest flexural properties showed the epoxy composite based on the combination of boric acid and aluminum nanopowder.

Effect of Electrical Parameters and Surrounding Gas on the Electroexplosive Tungsten Nanopowders Characteristics

Tungsten nanopowders were produced by the method of wires electrical explosion in the different gases. The study of phase and dispersed composition of the powders was carried out. The influence of electrical parameters such as the value of energy input in wire and the arc stage of the explosion was discussed. The factors that make for decreasing the particles size are the lower pressure of surrounding gas and the use of addition of chemically reactive gas.

Application of sakhaptinsk zeolite for ground water treatment

In this paper the natural zeolite from the Sakhaptinsk deposit (Krasnoyarsk Territory) was tested as adsorbent for removal of Fe²⁺, Fe³⁺, Mn²⁺, Ca²⁺, NH⁴⁺ from aqueous solutions and well water of Kozhevnikovsky District (Tomsk Region) under dynamic conditions. The physico-chemical and adsorption properties of the zeolite were studied by XRD, TGA, DTA, FTIR spectroscopy, SEM, chemical analyses. It is found that the removal efficiency was achieved for Fe<inf>total</inf> 96 wt%, Mn²⁺ − 93 wt%, Ca²⁺ − 100 wt%, NH⁴⁺ − 88 wt%.

Characteristics of nanopowders produced by electrical explosion of copper wires in argon with air additives

In this paper the dispersed, phase and chemical compositions of nanopowders produced by electrical explosion of wires in various gaseous medium were investigated. It is found that electrical explosion of copper wires in argon with little additives of air (1...2 vol.%) results in producing the nanopowders having high specific surface area (10.5...11 m2/g) and containing ~80 % of metal copper. The size of copper nanopowders decreases with increasing the content of reactive gas in argon (up to 30 vol. %) and their phase composition changes: the output of CuO is observed.

Effect of Boric Acid on Volatile Products of Thermooxidative Degradation of Epoxy Polymers

The polymeric materials are characterized by high flammability. The use of flame retardants in order to reduce the flammability of polymers can lead to the formation of toxic gaseous products under fire conditions. In this work we studied the effect of boric acid on the volatile products of thermooxidative degradation of epoxy polymers. The comparative investigations were carried out on the samples of the unfilled epoxy resin and epoxy resin filled with a boric acid at percentage 10 wt. %. The analysis of the volatile decomposition products and thermal stability of the samples under heating in an oxidizing medium was performed using a thermal mass-spectrometric analysis. It is found that the incorporation of boric acid into the polymer matrix increases the thermal stability of epoxy composites and leads to a reduction in the 2-2.7 times of toxic gaseous products

Scientific research on nanopowders diagnostics

The four parameters of chemical activity are proposed in the paper for testing of metal nanopowders and their mixtures stability to oxidation and chemical interaction. For estimation the thermodynamic conditions of the “metal nanopowder-gas” systems it is suggested to investigate their electrochemical characteristics.

Regulation of the Dispersed Composition of Aluminum Oxide Nanopowders Produced by Electrical Explosion

The feasibility of obtaining highly dispersed aluminum oxide powders by the electrical explosion of aluminum conductors in an inert gas atmosphere and the subsequent oxidation of aluminum particles by water prior to their contact with air is demonstrated. For a specific surface area of the initial aluminum powder of 6.5/g, the corresponding specific surface area of the resultant aluminum oxide nanopowder was as large as 300/g.

Mechanical and thermal properties of Moringa oleifera cellulose-based epoxy nanocomposites

Cellulose nanowhiskers were prepared by acid hydrolysis of drumstick fruit fibers from Moringa oleifera. It was incorporated into thermosetting epoxy matrix at various weight fractions (0.06, 0.12 or 0.18 wt%) to investigate their effect on the mechanical and thermal properties of resulting epoxy resin composite. Drumstick fruit nanofibers slightly increased the thermal stability of the prepared composites. The tensile modulus (31.4%) and bending modulus (38.2%) of the epoxy composites filled with 0.18 wt% cellulose nanowhiskers significantly increased in comparison with that of the neat cured epoxy resin. However, the tensile strength (48.7%) and bending strength (41.6%) of the composites significantly decreased as the 0.18 wt% nanowhiskers were added into the epoxy matrix. The nanowhiskers (0.18 wt%) can be efficiently used in the epoxy matrix to improve considerably the tensile and bending modulus of the composites as well as a slight increase in the thermal stability.