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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 4 (1958), S. 223-230 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The rate of absorption of chlorine from chlorine-nitrogen mixtures into solutions of ferrous chloride in 0.203 N aqueous hydrochloric acid was studied in a short wetted-wall column. Dimensional analysis and the film and penetration theories were used to infer, from the absorption rate data, that the chemical reaction between chlorine and the ferrous ion is second order. The absorption-rate results for experiments with a dilute gas phase agreed with theoretical predictions for absorption accompanied by a second order reaction with a reaction rate constant of 188 liters/(g. mole) (sec.). The results for experiments with pure chlorine gas deviated from the rest of the results, and they did not agree with the theoretical equations. It was shown that the assumption of a three-step mechanism for the chemical reaction, including the formation of a complex ion and the decompositon of this complex ion, explains, at least qualitatively, the deviations observed for the pure chlorine gas runs.
    Additional Material: 12 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 10 (1964), S. 727-733 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 6 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 4 (1958), S. 90-96 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Rates of flow of pure gases, both those with no adsorption and those with appreciable adsorption, were studied as a function of pressure level, pressure drop, and temperature for flow through 1/2-in.-diameter cylindrical plugs of activated carbon and of unsintered Vycor glass. Adsorption isotherms for the pure gases on Vycor glass were measured over the range of variables covered in the flow studies. A few measurements were made for bulk liquid flowing through a Vycor plug.Permeabilities, which are proportional to the rate of flow per unit of pressure drop, were satisfactorily correlated for hydrogen, helium, argon, and nitrogen by employing existing gas-phase flow theory. Permeabilities considerably larger than the values predicted from the nonadsorbed gas correlation, sometimes more than seventeen times as large, were observed for ethylene, propylene, and isobutane flowing through a Vycor plug. For the hydrocarbon-Vycor systems, permeabilities for vapor flow are as much as sixty times larger than for bulk liquid flow.The unusual flow phenomena for the hydrocarbon-Vycor systems are attributed to a rapid transport in the adsorbed layer. The total transport is treated as being the sum of gas-phase and adsorbed-layer flow. An equation describing adsorbed-layer movement is derived by utilizing a force balance together with thermodynamic principles. The resulting equation has just one empirical constant, and its use requires adsorption-isotherm data. It correlates very well the surface flow rates for the major range of the variables covered in this investigation. Rate measurements were made for adsorbed-layer concentrations ranging from about one tenth of a monolayer up through the capillary condensation region. Deviations in the one constant form of the equation are observed below one tenth of a monolayer. The available literature data on flow in adsorbed layers are reasonably well correlated by the same equation.
    Additional Material: 11 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 8 (1962), S. 134-135 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 8 (1962), S. 530-536 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The isothermal and isobaric flow of pure gases and vapors through microporous Vycor glass was investigated under such conditions that the gas-phase flow occurred by Knudsen diffusion. The isothermal flows and the isobaric flow of nonadsorbed gases are correlated by existing relationships.On the assumption that surface flow is a diffusive process and that equilibrium exists between the vapor and solid throughout the porous media, a correlation for the nonisothermal surface flow is developed. The factors determining the rate of surface flow are the physical properties of the solid, the temperature level and gradient, the enthalpy of adsorption, the surface concentration and spreading pressure of the adsorbed phase, and the activation energy and coefficient of resistance for surface diffusion. The latter two factors can be evaluated from isothermal surface flow measurements; hence no new arbitrary constants are required in the correlation. Agreement between predicted and measured surface flows is good for ethylene and propylene at a mean temperature of 25°C. Both the gas-phase and surface flows are from the cold to hot end of the porous solid.It is suggested that the use of temperature gradients in porous solids and plastic films for separating mixtures of vapors be investigated.
    Additional Material: 6 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 403-408 
    ISSN: 0887-6266
    Keywords: gas permeability ; selectivity ; barrier membranes ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Diffusion, solubility, and permebility coefficients were measured for He, Co2, Ar, and CH4 in polybutadiene (PB) and in polybutadiene reacted in the solid state to various extents with aqueous bromine. Analysis of the sorption curves and X-ray emission spectra showed that the bromination created a heterogeneous membrane with an outer brominated skin and an unreacted core. At relatively low extent of bromination, the diffusion and permeability coefficients for CO2, Ar, and CH4 decreased by two orders of magnitude, while the transport coefficients for He were virtually unchanged. The permeability coefficients for CO2, Ar, and CH4 became immeasurably small after about 3% bromination. The ideal separation factor for gas pairs with different molecular size increased with bromination, suggesting applications in gas separation processes. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 861-868 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Surfaces of polyethylene; poly(vinyl fluoride), poly(vinylidene fluoride), poly(tetrafluoroethylene), cellulose acetate butyrate, and polyoxymethylene were modified in various cold plasma reactions; feed gases to the plasma reactor were trifluoromethane, hexafluoroethane, and tetrafluoromethane. Using X-ray photoelectron spectroscopy (ESCA) to characterize the surfaces, it was established that the plasma reactions lead to fluorinated surfaces containing —CF3, —CF2, and —CF groups, All of these fluorinated surfaces exhibit advancing contact angles (with water) larger than 900. However, differences in the ESCA spectra, weight-gain/-loss measurements and scanning-electron-microscopy (SEM) photographs reveal that the mechanisms of fluorination in the various plasma environments are markedly different. The CF3H gas polymerizes in the gas phase of the plasma and deposits a smooth, fluorinated film on polymers and other substrates. The C2F6 plasma simultaneously etches polymers and polymerizes onto polymer surfaces. The CF4 plasma etches and reacts with the polymer surface but does not polymerize. For polyoxymethylene, the combined roughening (by etching) and fluorination of the surfaces lead to completely non-wettable surfaces (water contact angle approximately 180°). The highly non-wettable surfaces of these two polymers are believed to result from the physical etching and roughening at a very fine scale (approximately five micrometers) while the outermost surfaces are reacting to become highly fluorinated.
    Additional Material: 11 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 1223-1227 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Over the temperature range of 20 to 90°C, the equilibrium solubility of methane or argon in a star-branched polystyrene-polybutadiene (SB) block copolymer can be reliably estimated from a volume-fraction-weighted average of the homopolymer solubilities; the value of heat of solution for SB block copolymer lies between the two values associated with the constituent homopolymers. Diffusion coefficients for gases in the block copolymer are bracketed by the homopolymer values over the range of temperature employed, but the activation energies for diffusion in SB are higher than either of the homopolymer values. The anomalous temperature dependence and the inability of a computer simulation to reproduce experimental diffusion coefficients supported the concept of a temperature-dependent restriction on chain mobility in the polybutadiene regions of the block copolymer. This β factor embodies the relative reduction in the rate of gas diffusion through the B regions of the copolymer compared to B homopolymer; β has a value of about 2-3 at room temperature but decreases to unity when the polystyrene chains become mobile at the polystyrene Tg.
    Additional Material: 3 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 31 (1986), S. 901-910 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The rotating bed plasma reactor described here permits uniform surface modification of relatively large amounts of powder materials. Scale-up to even larger batches of solids appears to be feasible. Some preliminary experimental data on the plasma surface modification of polymer powders have been presented. The results show that the flow rate, time of treatment, and type of feed gas are important operating parameters which influence the final surface character. One particular application of plasma-modified polymer powders was explored; by crosslinking and/or chemically modifying only the outermost surface regions of these powders, various polymeric materials may be rendered useful for use in thermal storage slurries. The major advantage of the surface-modified plasma treated powders over the bulk-modified powders used previously is the retention of essentially all of the pristine polymer heat of fusion in the surface-modified materials.
    Additional Material: 7 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 1407-1418 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Liquid-phase sorption data are reported for the toluene-polyethylene system. The effects of fluorine plasma and inert-gas plasma treatments of the polymer surface were investigated. The presence of a fluorinated surface layer reduces initial solvent permeation rates, but the enhanced barrier property is lost when irreversible morphological changes occur during polymer swelling. A combination of chemical and morphological factors appears to be responsible for the observed temporary reduction in permeability; crosslinking of surface macromolecules was not a significant factor for the particular cases investigated in this work.
    Additional Material: 14 Ill.
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