IR spectroscopic identification of chemical bonds in macromolecules of polyacrylonitrile and carbon fibres

A hypothesis concerning the orbital mechanism of formation of the IR absorption spectra of polyacrylonitrile and carbon fibres was advanced and quantitatively substantiated. The previously advanced hypothesis concerning the gravitational mechanism of formation of chemical bonds for a gravitational constant of ∼10²⁸ cm³/g·sec²) was confirmed. __________ Translated from Khimicheskie Volokna, No. 1, pp. 46–48, January–February, 2007.     

Formation and growth of dispersed carbon particles during pyrolysis of ethylene,benzene, and naphthalene in a reflected shock wave

The formation and growth rates of dispersed carbon particles were determined experimentally for pyrolysis of ethylene, benzene, and naphthalene in a reflected shock wave at temperatures of 1920–2560 K and hydrocarbon concentrations in argon of 1.8–20%. The diameter of the particles formed was estimated (30–600 Å). The maximum rate of particle formation at various temperatures [(0.7–96) · 10¹⁶ cm⁻³·sec⁻¹] and the particle growth rate (0.002–0.036 cm · sec⁻¹) were determined from results of measurements of reaction (residence) times. For pyrolysis of benzene, the activation energy of the overall process of particle formation is 410 kJ/mole, and for all hydrocarbons studied, the activation energy of the overall process of particle growth is 5–50 kJ/mole. The surface average particle diameter increases with increasing concentration of the initial hydrocarbon at a constant temperature. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 4, pp. 82–89, July–August, 2007.     

Reaction of the carbon filler and binder in production of heating elements

IR spectroscopy showed that the components react on the CF—binder boundary, as indicated by the differences in the intensity and position of the absorption bands of CO₃ ²⁻ groups at the frequency of 1805 cm⁻¹ and C=O and >C-O> groups at 1739 and 1241 cm⁻¹. Thermogravimetric analysis showed that the activation energy of degradation of carbon fibre composites (CFC) increases. This indicates formation of thermostable material with a specific structure. The CFC obtained can be classified as difficultly combustible materials. __________ Translated from Khimicheskie Volokna, No. 1, pp. 37–38, January–February, 2008.     

Anodic oxidation of organic pollutants on a Ti/SnO<Subscript>2</Subscript>–Sb<Subscript>2</Subscript>O<Subscript>4</Subscript> anode

A Ti/SnO₂–Sb₂O₄ electrode was prepared by alternate Sn and Sb electrodepositions using the thermo-electrochemical method. The chemical, electrochemical, and structural characterization of the electrode was performed and it was tested in the anodic oxidation of several pollutants, phenol, ibuprofen, acid orange 7 (AO7), and diclofenac, all in aqueous 0.035 M Na₂SO₄ solutions at current densities of 10 and 20 mA cm⁻². After the 24 h assay, removal of chemical oxygen demand, total organic carbon (TOC) and absorbance were very high, especially at the higher current density. TOC removals presented the lowest value. However, after 24 h at 20 mA cm⁻², TOC removals were: phenol—94%; ibuprofen—83%; AO7—88%; and diclofenac—73%. Combustion efficiency and instantaneous and mineralization current efficiencies were also determined.     

Flameproofing modification of synthetic materials by laser radiation

A method of giving flameproof properties to materials and articles in light industry by modification with phosphorus-containing flame retardants under the effect of the energy from CO₂ laser radiation was developed. The optimum modification parameters (LR power density of 5.3 W/cm², treatment time of 30 sec, concentration of flame retardant (FR) in 5–10% solution, impregnation time of 100–120 sec), which allow obtaining flameproof materials with high performance properties were determined. The oxygen index of the cloth increased to 29.5–42%, the breaking strength increased by 8.5–21%, and the abrasion resistance increased by 5–12% without worsening the hygroscopicity and air permeability. The activating effect of laser radiation on the modification process was demonstrated; it resulted in an increase in the sorption capacity of the fibre structure of the materials, diffusion of FR into the bulk of the fibres, uniform distribution of the fibres in the form of finely disperse particles, intensification of the reaction of the components, ordering of the structure, and improvement in the physicomechanical properties of materials and articles in light industry. The method saves on expensive raw materials — flame retardants — due to conducting the modification from low-concentration solutions and allows expanding the line of flameproof materials. __________ Translated from Khimicheskie Volokna, No. 1, pp. 48–52, January–February, 2008.     

Theoretical aspects of predicting the electrostatic properties of textile materials

A theoretical method was developed for determining the electrostatic state of different chemical fibres. Mathematical relations that can be used to determine the electrical capacitance of chemical fibres of different configuration were obtained. The inverse problem was solved—finding the functional dependence of the dielectric constant of the material investigated on the initial capacitance. __________ Translated from Khimicheskie Volokna, No. 3, pp. 42–43, May–June, 2007.     

Basalt plastics — new materials for road construction

The effectiveness of using basalt fibres and substandard basalt wool — large-tonnage waste from chemical plants and nuclear generating stations — as a reinforcing component in road construction was demonstrated. Incorporation of basalt fibre or wool in asphalt concrete in an amount of up to 0.4 wt. % increased the strength characteristics of the asphalt concrete by 10–30%. The presence of a physicochemical reaction in the basalt fibre—polymer-asphalt binder system, which increased the strength characteristics, heat resistance, and lifetime of the polymer—asphalt—concrete, was demonstrated. IR spectroscopy showed ordering of the structure of the PAB due to formation of organosilicate compounds that strengthened the structure of the polymer asphalt concrete. Translated from Khimicheskie Volokna, No. 6, pp. 11–14, November–December, 2009.     

Nature of glowing generated by irradiation of pentaerythrite tetranitrate by an electron beam

Results of studying the nature of glowing generated by pentaerythrite tetranitrate (PETN) excitation by an electron beam with a mean electron energy of ≈250 keV and a current-pulse duration of 15 nsec are presented. The pulse-averaged power density of the beam is varied within 10⁶ ≤ P ≤ 10¹⁰ W/cm². For 10⁶ ≤ P ≤ 10⁸ W/cm², the main type of glowing is demonstrated to be pulsed cathodoluminescence of PETN. In the pre-detonation mode (P ≈ 10⁹ W/cm²), more inertial glowing is formed on the rear front of the luminescence peak, which is identified as the glowing of products of explosive transformation of PETN formed in the region of electron-beam travel. For P ≥ 5 · 10⁹ W/cm², an additional glowing pulse is formed, which is associated with formation and spreading of a dense plasma emerging owing to detonation of the entire mass of the sample. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 5, pp. 87–89, September–October, 2007.     

Metal-containing chemical fibres and their use in biotechnology

The possibility of using metal-containing fibres, including carbon fibres, as sorbents of proteins, viruses, and bacterial cells was demonstrated. It was found that silver-containing fibres can be effective adsorbents — carriers of Gluconobacter oxydans — a destroyer of thiodiglycol. Silver-containing fibres of different types exhibit bactericidal activity with respect to different bacterial cells; this activity is a function of the number and shape of the silver particles attached to the fibre. __________ Translated from Khimicheskie Volokna, No. 2, pp. 44–50, March–April, 2007.     

Effect of shock-wave loading on the internal microstructure and mechanical properties of fine-grained copper

It is shown that preloading of fine-grained copper with a the grain size of 0.5 m by a shock wave of intensity ≈25–50 GPa does not lead to changes in its internal microstructure and mechanical properties, and the dislocation density increases only slightly from 1.8 · 10¹¹ cm^s-2 in the initial state to (3.1–3.6) · 1011 cm^s-2 after shockwave loading. An increase in shock wave intensity to pressures > 55 GPa leads to a decrease in the dislocation density to 2.5 · 10⁹ cm^s-2, an increase in the grain size to ≈19 fum, the occurrence of microtwins inside the grains, and a reduction in the mechanical properties of fine-grained copper to the level of coarse-crystalline copper.     

Spectral properties of Er<Superscript>3+</Superscript> in alkali-zinc-tellurite,barium-tellurite-molybdate,and fluoride glasses

Glasses of three compositions—TeO₂ · ZnO · N₂O (TZN), where N is Li, Na, or K; TeO₂ · MoO₃ · BaO (TMB); and ZrF₄ · BaF₂ · LaF₃ · AlF₃ · NaF (ZBLAN)—activated by Er³⁺ or Yb³⁺ and Er³⁺ ions were synthesized and investigated. For the ZBLAN glass, the brightest luminescence of Er³⁺ ions in the visible range was observed under excitation by the irradiation of a diode laser with the generation wavelength 0.98 μm. The TZN glass is not inferior in the intensity of luminescence with the wavelength 1.55 μm to the TMB glass, having phonons of higher energy than those for the TZN glass (940 and 740 cm⁻¹, respectively). A glass was prepared with a high content of molybdenum oxide. The possibility to increase the up-conversion efficiency in tellurite glasses is considered.     

Development of technology for high-strength nonwoven materials

It was found that chemical fibres modified with organosilicon compounds have better physicomechanical properties than the initial fibres. The effect of the chemical structure and properties of the organosilicon compounds on the modification process and physicomechanical properties of the modified fibres was investigated. The optimum process parameters for manufacture of thermobonded nonwovens with elevated physicomechanical properties were determined. It was shown that treatment of the fibre web with a catalyst — hydrogen peroxide — allows eliminating the stage of heat treatment of the webs after application of the modifier which reduces the power consumed for production of nonwovens. __________ Translated from Khimicheskie Volokna, No. 2, pp. 21–23, March–April, 2006.     

The manufacturing process for production of combined conducting fibres

The equations reported here can be used for calculating the physicomechanical parameters of combined conducting fibres. The breaking load of combined conducting fibres is basically a function of the strength of the core — the complex chemical fibre. __________ Translated from Khimicheskie Volokna, No. 5, pp. 24–26, September–October, 2007.     

Synthesis, Supramolecular Architecture and DNA Binding Studies of a Novel Heterotrinuclear FeIII/CoII/FeIII Complex: [Co(phen)2][Fe(phen)(CN)4]2·4H2O (phen?=?1,10-phenanthroline)

A novel cyano-bridged heterotrinuclear Fe^III/Co^II/Fe^III complex, [Co(phen)₂][Fe(phen)(CN)₄]₂·4H₂O (1) (phen = 1,10-phenanthroline), has been synthesized under solvothermal conditions, and characterized by elemental analysis, FI-IR spectrum and single-crystal X-ray diffraction. The structure analysis reveals complex 1 is constructed into a 3D supramolecular architecture through abundant intermolecular non-covalent interactions. According to the supramolecular self-assembly of complex 1, five types of π–π stacking models of phenanthroline ligands, hydrogen bonds formed by four lattice water molecules, and C–H···N weak interactions involving cyano groups are all observed. Electronic absorption spectroscopy and fluorescence titration studies of the interaction between complex 1 and calf thymus DNA are suggestive of an intercalative binding mode with an intrinsic binding constant of 7.95 × 10³ M⁻¹ and a linear Stern–Volmer quenching constant of 1.033 × 10⁵ M⁻¹.     

Detonation of mixtures of bistrinitroethylnitramine with carbon

The dependence of detonation rate on charge density is determined for bistrinitroethylnitramine and stoichiometric mixtures of it with carbon (soot, graphite with different particle sizes). A characteristic feature of dependences for mixtures of BTNENA with carbon is a discontinuity whose position corresponds to the following charge densities, g/cm³: 1.43 for a mixture with soot, 1.15 and <0.4 g/cm³ for a mixture with graphite (particle size 10⁻³cm) and 5.6·10⁻³ cm respectively). The treatment of experimental results is provided. Institute of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 5, pp. 97–99, September–October, 1994.     

Fabrication of carbon fibres from wet-spun commercial polyacrylonitrile fibres

The possibility of fabricating carbon fibre from commercial PAN fibres for textile applications was demonstrated. It is necessary to make some changes in the temperature—time conditions for total completion of the thermal stabilization process. Better strength of the carbon fibres, equal to 1401 MPa, was attained in conducting thermal stabilization cycle B. __________ Translated from Khimicheskie Volokna, No. 5, pp. 31–33, September–October, 2006.     

Epoxidation of karanja (Pongamia glabra) oil by H2O2

Epoxidation of karanja oil (KO), a nondrying vegetable oil, was carried out with peroxyacetic acid that was generated in situ from aqueous hydrogen peroxide and glacial acetic acid. KO contained 61.65% oleic acid and 18.52% linoleic acid, respectively, and had an iodine value of 89 g/100 g. Unsaturated bonds in the oil were converted to oxirane by epoxidation. Almost complete epoxidation of ethylenic unsaturation was achieved. For example, the iodine value of the oil could be reduced from 89 to 19 by epoxidation at 30°C. The effects of temperature, hydrogen peroxide-to-ethylenic unsaturation ratio, acetic acid-to-ethylenic unsaturation ratio, and stirring speed on the epoxidation rate and on oxirane ring stability were studied. The rate constant and activation energy for epoxidation of KO were 10⁻⁶ L·mol⁻¹·s⁻¹ and 14.9 kcal·mol⁻¹, respectively. Enthalpy, entropy, and free energy of activation were 14.2 kcal·mol⁻¹, −51.2 cal·mol⁻¹·K⁻¹, and 31.1 kcal·mol⁻¹, respectively. The present study revealed that epoxides can be developed from locally available natural renewable resources such as KO.     

Thermal decomposition of polyester polyurethane and its elastomers exposed to γ-radiation

The thermal-decomposition parameters of unplasticized and nitrate ester plasticized polyester polyurethane elastomers with unsaturated carbon—carbon bonds in the initial state and after irradiation with doses of 120–380 kGy (γ-quanta ⁶⁰Co) were determined using dynamic thermogravimetry and differential scanning calorimetry. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 2, pp. 133–138, March–April, 2006.     

Calculation-graphic analysis of the IR spectrum of a glass batch containing sodium borate and silicate and boric and silicic acids

A calculation-graphic analysis of the IR spectra of sodium borate and silicate as components of a glass batch, obtained in aqueous medium, and probable contaminants — boric and silicic acids — was conducted. It was found that several bands called critical coincide or are close together in the spectrum. Among them are the bands at 947–959, 1004–1005, 1079–1086, 1195–1200, 1450–1453, and 1686–1690 cm⁻¹ characterizing the fundamental vibrations of the atoms in bonds in cross-linking groups, and they cannot be distinguished by either the wavenumber or the intensity so that it is impossible to identify the phases formed. The concept of “conditionally distinguishable bands” in the spectra of comparable substances was introduced. The absolute degrees of difference in the wavenumber and intensity, order of sorting the bands, and determination of the boundaries of the critical regions of the spectrum of the batch were examined. __________ Translated from Steklo i Keramika, No. 8, pp. 3–8, August, 2007.     

Intensification of thermooxidation of polyacrylonitrile fibres

It was found that in thermooxidation of PAN fibres in air by the conductive (contact) method, the density of 1.38–1.40 g/cm³, required for subsequent high-temperature treatment, is attained in 30–60 min. The chemical composition and equilibrium sorption of the PAN fibre oxidized by convective tempering do not differ significantly from the fibre fabricated in industrial conditions in convective tempering. All-Russian Scientific-Research Institute of Polymer Fibres, Mytishchi. Translated fromKhimicheskie Volokna. No. 6, pp. 22–24, November–December, 1999.