Key words: supercritical state, structure of water, pair correlation functions
A new approach to the problem of the structure of liquid and supercritical water has been suggested that is based on the idea of preferential variations of the nearest ordering. The transition of water into the supercritical state is described in the terms of this conception. Analysis of some experimental data allowed us to show that the infinite cluster of H-bonded water molecules ceased to exist in the vicinity of critical isotherm. The phenomena associated with the surmounting of the percolation threshold may be important for the development of new supercritical technologies.
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7.0.100-2018
Water in the Supercritical State / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2007. – Т. 2. – № 2. – С. 5-19. - DOI:
TRANSLIT
Sverhkriticheskoe sostoyanie vody / – Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2007. – Т. 2. – № 2. – S. 5-19. - DOI:
En
Water in the Supercritical State. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 2, 5-19 (2007). https://doi.org/
Key words: supercritical fluid impregnation, spiroantroxazin, thermoplastic polymers
The impregnation of several thermoplastic polymers (polyethylene, polypropylene, polymethylmethacrylate, polycarbonate) with spiroxazin photochrome (SAO) having a stable unexcited form A, and photoexcited (colored) form B, was performed in supercritical CO2. It is found that, unlike other polimers under study, the supercritical fluid impregnation of polycarbonate (PC) with SAO causes the dramatic stabilization of its colored form B. The bleaching time of SAO in PC after its photoexcitation (900 c) is two orders of magnitude higher than that in polypropylene. Moreover, after supercritical fluid impregnation of PC up to 20 % of SAO is originally formed in colored form, which is not bleachable for 90 days (the whole period of observation), i.e. is extremely stable. The temperature and pressure effects on SAO concentration in different polymer matrixes were measured. At least some part of SAO incorporated into the polymeric matrix forms nanocrystals of ~ 10 ÷ 20 nm size. Possible mechanisms of the observed effect of the colored SAO form stabilization in the polycarbonate matrix are discussed.
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7.0.100-2018
Effect of Stabilization of Colored Form of Spiroxazin Photochrome in Polycarbonate Matrix / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2007. – Т. 2. – № 1. – С. 78-85. - DOI:
TRANSLIT
Effekt stabilizacii okrashennoj formy fotohroma spirooksizinovogo ryada v matrice polikarbonata / – Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2007. – Т. 2. – № 1. – S. 78-85. - DOI:
En
Effect of Stabilization of Colored Form of Spiroxazin Photochrome in Polycarbonate Matrix. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 1, 78-85 (2007). https://doi.org/
Key words: radiation-conduction heat transfer, critical point, supercritical fluid
The results of experimental study of the parameter χ = (λeff/λcond) about a critical point of n-hexane are presented. The measurements are made using the flat layer method with interference visualization. A crucial decrease in the fraction of radiation heat transfer is established as temperature is approaching the critical point from both liquid and supercritical fluid state sides.
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ГОСТ
7.0.100-2018
Radiation-Conduction Heat Transfer about a Critical Point of n-Hexane / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2007. – Т. 2. – № 1. – С. 69-77. - DOI:
TRANSLIT
Radiacionno-konduktivnyj perenos tepla vblizi kriticheskoj tochki n-geksana / – Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2007. – Т. 2. – № 1. – S. 69-77. - DOI:
En
Radiation-Conduction Heat Transfer about a Critical Point of n-Hexane. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 1, 69-77 (2007). https://doi.org/
Key words: polymers, porosity, supercritical fluids, carbon dioxide
Methods of processing of bioresorbable polymers (polylactide and polylactide/ polyglycolide copolymers) in gas, liquid and supercritical media are studied. It is shown that processing of such polymers in supercritical medium results in high amounts of carbon dioxide absorbed in a polymer matrix. The following desorption of carbon dioxide leads to the creation of highly developed porosity (up to 2 cm3/g). The treatment of the polymers under study with liquid and gaseous carbon dioxide gives the total pore volume of 0.1 ÷ 0.3 cm3/g.
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7.0.100-2018
Formation of Porosity in Bioresorbable Polymers by their Treatment in Gaseous, Liquid and Supercritical Carbon Dioxide / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2007. – Т. 2. – № 1. – С. 61-68. - DOI:
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Poluchenie poristyh biorezorbiruemyh polimerov obrabotkoj dioksidom ugleroda v gazoobraznom, zhidkom i sverhkriticheskom sostoyaniyah / – Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2007. – Т. 2. – № 1. – S. 61-68. - DOI:
En
Formation of Porosity in Bioresorbable Polymers by their Treatment in Gaseous, Liquid and Supercritical Carbon Dioxide. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 1, 61-68 (2007). https://doi.org/
Key words: bioresorbable polymers, polymer microparticles, supercritical carbon dioxide, acoustic excitation
A new approach to control the process of «dry» (without any use of organic solvents) synthesis of bioresorbable polymer microparticles and porous fibers has been proposed and developed. It is based on the combination of treatment in supercritical fluids and intensive acoustic excitation. Low molecular weight (Mw ~ 1000) ε-polycaprolactone and D,L-polylactide microparticles and their agglomerates which can be used as a drug delivery vehicles were produced by spraying of the polymers plasticized in supercritical CO2 through the pulse nozzles. The significant lowering of the initial D,L-polylactide viscosity has been achieved by intensive acoustic agitation in supercritical fluid environment followed by the morphology changes of the final product. No noticeable alterations of both polymer molecular weight and polydispersity (Mw/Mn ratio) after the treatment were detected.
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7.0.100-2018
Fabrication of Bioresorbable Polymer Microparticles with Supercritical Fluids / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2007. – Т. 2. – № 1. – С. 53-60. - DOI:
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Poluchenie mikrochastic biorezorbiruemyh polimerov s pomoshch'yu sverhkriticheskih sred / – Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2007. – Т. 2. – № 1. – S. 53-60. - DOI:
En
Fabrication of Bioresorbable Polymer Microparticles with Supercritical Fluids. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 1, 53-60 (2007). https://doi.org/
Key words: high temperatures, high pressures, supercritical fluids, vibrational spectroscopy, UV-Vis absorption spectroscopy
Various experimental approaches and cells for spectroscopic studies at high temperatures and pressures (up to 500 °C and 1000÷1500 bar) are described. The cells for absorption spectroscopy cover a wide range of light radiation from mid IR to ultraviolet. The use of a simple Raman cell, either with microscope or directly in the sample compartment of a spectrometer, is discussed in detail. It is worth noticing that all designs under consideration provide high accuracy of quantitative measurements.
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7.0.100-2018
Spectroscopic Techniques for Studying Liquids and Supercritical Fluids at High Temperatures and Pressures / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2007. – Т. 2. – № 1. – С. 40-52. - DOI:
TRANSLIT
Tekhnika spektral'nyh issledovanij zhidkostej i sverhkriticheskih flyuidov pri vysokih temperaturah i davleniyah / – Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2007. – Т. 2. – № 1. – S. 40-52. - DOI:
En
Spectroscopic Techniques for Studying Liquids and Supercritical Fluids at High Temperatures and Pressures. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 1, 40-52 (2007). https://doi.org/
Key words: phase behavior, critical point, multi-component phases, fiberoptic reflectometry, flow reactor
High precision two-channel fiberoptic reflectometer (OPR) has been developed for investigation of phase behavior of multi-component supercritical fluids in different areas of reactor. Phase behavior of binary mixtures СО2 + acetone, СО2 +methanol has been measured in a batch reactor in wide ranges of temperatures (20 ÷ 700°C) and pressures (50 ÷ 200 bar). The experimental data were compared with that calculated by Lorentz - Lorenz equation. Phase behavior of СО2 + acetophenone mixture in a flow capillary reactor has been investigated for different concentrations of acetophenone (7.5, 21.2, 34.1%). Our experiments with СО2 + methanol mixtures show the possibility to study phase behavior of multicomponent fluids in a flow supercritical fluid reactor filled with catalyst.
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7.0.100-2018
Two-channel Fiberoptic Reflectometry of Supercritical Media / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2007. – Т. 2. – № 1. – С. 28-39. - DOI:
TRANSLIT
/ – Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2007. – Т. 2. – № 1. – S. 28-39. - DOI:
En
Two-channel Fiberoptic Reflectometry of Supercritical Media. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 1, 28-39 (2007). https://doi.org/
Key words: supercritical fluids, processing of plant raw materials, lignin
Physical chemistry of polymers and thermodynamic compatibility of biopolymers theory are applied to the analysis of the behavior of the lignin-cellulose matrix of wood materials under the treatment in supercritical (SC) media. The most promising applications of SC fluid technologies in the area of chemical processing of wood and non-wood raw plant materials are discussed.
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7.0.100-2018
Prospects in Applying Supercritical Fluid Technologies to the Chemistry of Raw Plant Material / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2007. – Т. 2. – № 1. – С. 16-27. - DOI:
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Perspektivy primeneniya sverhkriticheskih flyuidnyh tekhnologij v himii rastitel'nogo syr'ya / – Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2007. – Т. 2. – № 1. – S. 16-27. - DOI:
En
Prospects in Applying Supercritical Fluid Technologies to the Chemistry of Raw Plant Material. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 1, 16-27 (2007). https://doi.org/
Key words: supercritical fluids, thermal conductivity, hydrocarbons
Theoretical and experimental studies of combined radiation-conduction heat transfer in flat layers of hydrocarbons in sub- and supercritical regions of parameters are reviewed. Within a narrow temperature region around the critical point the radiation constituent of thermal conductivity approaches nil, but outside it the radiant flux can be comparable with the conductive one. It must be noted that this important factor must be taken into account while the equipment for several processes involving hydrocarbons is developed. This is of special importance for such processes as heavy oil treatments and fractionation, which employ propane, pentane, hexane, toluene and other hydrocarbons in sub- and supercritical state. The neglect of this factor may lead to non-optimal and even incorrect technical solutions and also to unjustified material and energetic expenses on the stage of industrial implementation.
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7.0.100-2018
Combined Radiation-Conduction Heat Transfer in Sub- and Supercritical Fluid Media / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2007. – Т. 2. – № 1. – С. 3-15. - DOI:
TRANSLIT
Radiacionno-konduktivnyj perenos tepla v sub- i sverhkriticheskih flyuidnyh sredah / – Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2007. – Т. 2. – № 1. – S. 3-15. - DOI:
En
Combined Radiation-Conduction Heat Transfer in Sub- and Supercritical Fluid Media. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 1, 3-15 (2007). https://doi.org/
Key words: polymer matrix, polyarylate, solubility, supercritical carbon dioxide, impregnation, disperse dye Red 13
Impregnation of polymer films (polyarylate DV, polymethylmetacrylate, chitosane, etc.) with some anthraquinone and azobensene dyes from their solutions in supercritical carbon dioxide (SC-CO2) is investigated on qualitative level. Quantitative measurements are carried out with disperse dye Red 13 and polyarylate DV (PAR). The effect of pressure at temperatures ranged from 35 to 40 °C on the dye solubility in SC-CO2 is studied by UV-spectroscopy. It is shown that at 35 °C and 13.8 MPa the dye concentration in PAR can reach 0.2 wt. % (2.8·10-5 mol/l). Kinetic curve of Red 13 diffusion from SC-CO2 solution into PAR matrix at 40 °C and 10 MPa has a monotonic character with saturation. The experimental results are analyzed in the framework of the theoretical model that implies a low solubility of functional additive (in this case dye) in a transportation fluid (SC-CO2).
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7.0.100-2018
Impregnation of Polymer Matrixes with Dyes Using Supercritical Carbon Dioxide / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2006. – Т. 1. – № 2. – С. 69-80. - DOI:
TRANSLIT
Impregnaciya krasitelyami polimernyh matric s pomoshch'yu sverhkriticheskogo dioksida ugleroda / – Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2006. – Т. 1. – № 2. – S. 69-80. - DOI:
En
Impregnation of Polymer Matrixes with Dyes Using Supercritical Carbon Dioxide. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 2, 69-80 (2006). https://doi.org/
Key words: supercritical, gaseous, solid carbon dioxide, chitosan, modification
The influence of different carbon dioxide in different aggregate states (gaseous, solid, supercritical) onto properties of chitosan is studied. The interdependence of the physical and chemical properties of the polymer material under study on its structure and CO2 sorption is demonstrated and analyzed.
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7.0.100-2018
Modification of Chitosan by Carbon Dioxide / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2006. – Т. 1. – № 2. – С. 60-68. - DOI:
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Modifikaciya hitozana s ispol'zovaniem dioksida ugleroda / – Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2006. – Т. 1. – № 2. – S. 60-68. - DOI:
En
Modification of Chitosan by Carbon Dioxide. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 2, 60-68 (2006). https://doi.org/
Key words: polymers, porosity, supercritical fluids, carbon dioxide
Previously developed by authors two-stage method for creating a desired porosity is applied to several polymeric materials, such as polytetrafluoroethylene, ultra high-molecular weight polyethylene, polyether ether ketone, polyaryl ether ketone 11, polyamide 6, shock-resistant polystyrene, acrylonitrile-butadiene-styrene co-polymer, and polyvinylchloride. It consists of polymer treatment with carbon dioxide in supercritical state and subsequent heating at atmospheric pressure. It is demonstrated that the method gives different results being applied to crystalline and amorphous polymers: no porosity is formed in crystalline materials, whereas substantial porosity (up to 0.9 cm3·g-1) is formed in polymers, in which amorphous domains dominate.
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7.0.100-2018
Crystalline and Amorphous Polymer Treatment in Supercritical Media Aimed at Creation of Porosity / – Текст : непосредственный // Сверхкритические Флюиды: Теория и Практика.. – 2006. – Т. 1. – № 2. – С. 49-59. - DOI:
TRANSLIT
Obrabotka kristallicheskih i amorfnyh polimerov v sverhkriticheskih sredah s cel'yu sozdaniya poristosti / – Sverhkriticheskie Flyuidy: Teoriya i Praktika.. – 2006. – Т. 1. – № 2. – S. 49-59. - DOI:
En
Crystalline and Amorphous Polymer Treatment in Supercritical Media Aimed at Creation of Porosity. Sverhkriticheskie Flyuidy: Teoriya i Praktika, 2, 49-59 (2006). https://doi.org/