Stabilization of the properties of epoxy materials in response to ionizing radiation is an important task for predicting the service life of the product. This study investigated the effect of γ-radiation on the structure and mechanical and thermal stability of epoxy nanocomposites with TiO 2 nanoparticles (n-TiO 2 ). The oxidation of epoxy chain bonds at doses above 42 kGy was shown using IR spectroscopy. The addition of n-TiO 2 makes it possible to increase the strength and strain and also stabilize the mechanical and thermal properties of the composite with respect to γ-radiation.

The regularities of the formation, as well as the structure and properties of the epoxy nanocomposites synthesized via curing with 4,4′-diaminodiphenylmethane and triethylamine of the ED-20 epoxy binders modified by spherical small ( r ~ 2 nm) narrowly dispersed silver nanoparticles with oligostyrylmono-carboxylate ligands were studied by SEM, UV–Vis spectroscopy, and DSC methods. The limiting initial concentration of silver oligostyrylmonocarboxylate in the modified binder, which affords uniform distribution of the silver nanoparticles ( r ~ 8–20 nm) in the nanocomposites, was estimated at 2.5 wt %. The silver nanoparticles cause a slight decrease in the glass transition temperature and do not affect the mechanical characteristics of the epoxy nanocomposites. The thermophysical characteristics of the nanocomposites depend on the topology of the epoxy matrix.

The thermolysis of Zr(BH4)4 vapor at 573 and 623 K in a vacuum of 1.33 × 10−1 Pa was studied. Nanosized zirconium diboride was produced as an X-ray amorphous powder and a crystalline film. According to electron microscopy data, the X-ray amorphous zirconium diboride powder obtained at 573 or 623 K consists of spherical particles 30–40 nm in diameter, which is in quite a good agreement with the equivalent particle diameter (∼35 nm) calculated from the specific surface area of ZrB2. After annealing at 1273 K, the X-ray amorphous zirconium diboride powder crystallizes into a hexagonal lattice with the unit cell parameters a = 0.3159 nm and c = 0.3527 nm. The coherent scattering length D hkl is ∼27 nm. The zirconium diboride film produced at 573 or 623 K crystallizes into a hexagonal lattice with the unit cell parameters a = 0.3163−0.3168 nm and c = 0.3524−0.3531 nm. The coherent scattering length D hkl is ∼14 nm. The thickness of the ZrB2 film on quartz, glass ceramics, and stainless steel is 5–7 μm. The microhardness of the film on a stainless steel substrate under a load of 20 g is 17.8 GPa.

The process of obtaining and micronization of polymeric materials using an original method of nonisothermal polymerization in the medium of supercritical fluid is investigated. Polystyrene microparticles and fibers are synthesized. The influence of the conditions of the microdispersion process on the morphology of the isolated product is evaluated.

Nanoporous polymer networks of N − vinylpyrrolidone (VP) with dimethacrylates of ethylene, 1,6 − hexanediol and triethylene glycol were obtained by three-dimensional free-radical copolymerization in bulk using branched copolymers as pores templates. The branched copolymers consisted of monomers of the same type to provide their thermodynamically compatibility and solubility in the appropriate mixtures of VP − dimethacrylate. They were synthesized by radical copolymerization in toluene under chain transfer condition and characterized by the FTIR, 1H NMR, GPC, DSC and DLS methods. After curing of the stable visually homogeneous monomer-polymer mixtures, polymer composites with optical properties differed from conventional network copolymers were obtained due to the micro- or macrophase separation. According to the gravimetry, FTIR, GPC and DSC data, the macromolecular additives were partly extracted by isopropyl alcohol as a “good” solvent. The hierarchical nanoporous structure of the obtained gels was demonstrated by the SEM and low-temperature nitrogen adsorption methods. Polymer networks crosslinked with dimethacrylates of ethylene and triethylene glycol contained mostly mesopores, while pores less than 20 nm predominated in the N − vinylpyrrolidone copolymer crosslinked with 1,6 − hexanediol dimethacrylate. It was shown that the values of the specific surface area increased by an order in comparison with conventional polymer networks and reached about 11–16 m2/g.

A method of preparing nanoporous polymer networks containing N-vinylpyrrolidone units via the crosslinking radical copolymerization in bulk performed in the presence of amphiphilic N-vinylpyrrolidone copolymers with the branched morphology and different physicochemical characteristics is developed. It is shown that macromolecular nanoobjects may be extracted from polymer composites using good solvents, such as chloroform and isopropyl alcohol. The physicomechanical, thermal, and diffusion–sorption properties of polymer composites before and after their extraction are compared. SEM and low-temperature nitrogen adsorption measurements reveal that nanosized pores are contained in the network copolymers after extraction of the polymer additives. The specific surface area, total pore volume, pore size, and pore-size distribution are determined. The maximum specific surface area of polymer networks attains ~26 m2/g, and mesopores compose the main type of pores.

The polymer networks with nanoporous structure were obtained by the crosslinking free-radical copolymerization of N -vinylpyrrolidone with triethylene glycol dimethacrylate in bulk in the presence of amphiphilic copolymer and its fractions as templates. The templating agents consisted of copolymer or their fragments with similar monomer units and different molecular weight. Macromolecular templates were shown to be removed from the polymer composite by Pr i OH leaving the pores. The values of the specific surface areas, the total pore volumes, pore size, and pore size distribution were measured by the method of low-temperature nitrogen absorption. The maximum value of the specific surface area was calculated to be ~26 m 2 g –1 . The value was significantly higher than that for the usual copolymer network. The relationship between specific surface area, parameters of pores, and macromolecular structure of template has been established. It is shown by Brunauer—Emmett—Teller method that the macromolecules having a branched architecture are more effective for the preparation of the polymer network with more developed specific surface area and narrow pore size distribution.

The copolymer of N-vinylpyrrolidinone with a branched topology was proposed as a promising blowing agent to produce mesoporous network copolymers.

The mechanical and thermomechanical properties of metal-containing epoxy composite films based on silver nanoparticles synthesized in situ are investigated. There is a nonmonotonic dependence of the mechanical properties on the concentration of silver myristate used as a precursor. It is found for the first time that the breaking strength and elastic modulus increase by a factor of 1.8–1.5 relative to those of the unmodified matrix at a small concentration of precursor nanoparticles (on the order of 0.1 wt %). DSC and thermomechanical studies reveal that the glass-transition temperature decreases slightly (by 5–6°C) as the precursor concentration is increased to 0.5 wt %, thereby suggesting a weak plasticization of the modified epoxy matrix. On the basis of the spectrophotometry data measured in the region of surface plasmon resonance of silver nanoparticles (420–425 nm) and SEM data, it is inferred that the in situ strengthening of an epoxy nanocomposite based on epoxy resin ED-20, triethylamine, and silver myristate is attained because silver nanoparticles smaller than 20 nm in size and having a narrow particle-size distribution are formed during curing.

Исследованы механические и термомеханические свойства пленок металлосодержащих эпоксидных композитов на основе наночастиц серебра, синтезированных in situ. Установлена немонотонная зависимость механических свойств от концентрации прекурсора – миристата серебра. Впервые обнаружено увеличение прочности при разрыве и модуля упругости в 1.8–1.5 раз по сравнению с немодифицированной матрицей при малой концентрации прекурсора наночастиц (порядка 0.1 мас. %). Методами ДСК и термомеханики показано незначительное снижение температуры стеклования на 5–6°С с повышением концентрации прекурсора до 0.5 мас. %, свидетельствующее о слабой пластификации модифицированной эпоксидной матрицы. На основании данных спектрофотометрии в области поверхностного плазмонного резонанса наночастиц серебра (420–425 нм) и данных СЭМ сделан вывод о том, что упрочнение эпоксидного нанокомпозита in situ на основе эпоксидной смолы ЭД-20, триэтиламина и миристата серебра достигается за счет формирования в процессе отверждения наночастиц серебра, меньших 20 нм, с узким распределением по размеру.

It was found that under mixing of aqueous solutions of copolymers and toluene solutions of C60 two types of polymer composites can be produced with different matrix structure, the fullerene content and an aggregation degree. The dimethacrylate enriched macromolecules migrate to toluene and the VP units enriched copolymer chains remain in water to form copolymer micelles and their aggregates in these media that solubilize and encapsulate the fullerene. The structure and properties of obtained polymer composites were studied by GPC with dual detection (RI and MALLS), FT-IR, WAXS and SAXS methods. It is shown that in a composite based on N-vinylpyrrolidone copolymer isolated from toluene the fullerene form larger particles, compare to that isolated from water. According to SAXS, the fullerene particles in a solid copolymer are organized in spherical objects with fine coil-like structure. The stability of the composites in water, ethanol, and chloroform was shown to depend on the original polymer matrix structure and on copolymer/fullerene ratio. POLYM. COMPOS., 35:1362-1371, 2014. (c) 2013 Society of Plastics Engineers

Nonpyrophoric tungsten powders with an average particle size of about 30 nm were obtained by pyrolysis of tungsten hexacarbonyl in a flow of microwave discharge nitrogen plasma. It is found that these powders are stable in air up to 300°C. The reason for such stability is that the structure of powder particles is of the core-double shell type, in which the metal core is covered with an oxide film approximately 1 nm in thickness, coated in turn with roentgenoamorphous layer consisting of carbon, oxygen, and nitrogen atoms. It is also established that the powders under investigation mainly release carbon oxides (CO and CO 2 ) and water into the gas phase upon heating in vacuum. Among the molecules present in the gas phase in small concentrations, nitrogen monoxide (NO) and formaldehyde (H 2 CO) are worth mentioning apart from C1–C3 hydrocarbons.

The conditions for the formation of the particle-size and phase composition of titanium dioxide upon the oxidation of titanium tetrachloride in a stream of oxygen-containing microwave discharge plasma have been studied. The possibility of controlling the particle size of the resulting powder in the range of 50–100 nm by changing various operating parameters has been shown. The conditions for obtaining a nearly single-phase powder of the anatase or rutile modification have been found.

The effect of operating parameters of the oxidation of aluminum powder in a stream of air microwave plasma on the particle size of the obtained Al 2 O 3 has been studied. The possibility of improving the particle size of the powder by pretreatment the starting aluminum with chemicals activating particle combustion in a reactor has been investigated. Ways of controlling the particle size of produced aluminum oxide nanopowders in the range of 20–80 nm have been found.

We have studied the reaction between NaBH4 and TiCl4 at elevated temperatures in the range 570–1020 K and pressures of up to 10 MPa, with no solvent. The results indicate that nanoparticulate titanium diboride forms at temperatures above 820 K. According to electron microscopy data, the titanium diboride powder obtained at 1020 K consists of spherical particles 35–50 nm in diameter, in reasonable agreement with the equivalent particle diameter of ≃45 nm evaluated from the specific surface area of the TiB2 and with the crystallite size Dhkl ≃ 30 nm evaluated from X-ray diffraction data.

The availability of production of a silicon carbide nanodispersed powders in plasma-chemical processes are investigated by hydrogen reduction of silicon tetrachloride with hydrocarbon at use of argon electro-arc and nitrogen microwave plasma. The availability of production in both cases of single-phase powders of cubic form with the average size of particles in a range of 21-150 nm is shown depending on various technological parameters.