GLORIA — GEOMAR Library Ocean Research Information Access

1

Digitale Medien

The mechanism of post cure of viton ARegistered trademark of E. I. du Pont de Nemours & Co., Inc. Fluorocarbon elastomerBased on a lecture delivered at the 2nd International Synthetic Rubber Symposium, London, October 1960, by arrangement with Rubber and Plastics World. (1961)

Smith, J. F. ; Perkins, G. T.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 5 (1961), S. 460-467

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: The necessity for oven post-curing Viton A vulcanizates is explained in the following way: The formation of crosslinks is accompanied by the elimination of HF from the polymer. In the subsequent reaction of HF with the magnesium oxide present as acid acceptor water is formed which acts to inhibit the full development of cure unless it is removed from the vicinity of the polymer by post-curing in an open system. Measurement of the rate of elimination of water from the polymer serves as a method of following the development of crosslinking during cure. Approximately two moles of water, derived from four moles of hydrogen fluoride, are associated with the use of one mole of diamine curing agent. This ratio is confirmed by independent estimates of the relationship of crosslinking density to curing agent level based on measurements of swollen compression moduli.

Zusätzliches Material: 11 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1961.070051612

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2

Digitale Medien

Pore diffusion in silver catalysts (1962)

Masamune, Shinobu ; Smith, J. M.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 8 (1962), S. 217-221

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Diffusion rates were measured at atmospheric pressure and room temperature for helium and nitrogen in pelleted silver catalysts. Pellets were prepared from three silver salts giving different micropore characteristics. The data showed that the diffusion was of the bulk type and that the micropores had no effect, indicating that mass transfer was predominantly in the macropore region. For each kind of material data were obtained for five pellet densities corresponding to macropore volume fractions from 0 up to 0.7.Effective diffusivities and labyrinth factors ψ were evaluated and found to increase with macropore porosity. The linear relationship between ψ and void fraction proposed by Buckingham for diffusion through soils fitted the data at high void fractions. A generalized form of the Maxwell equation containing three constants was derived. A single-constant form of this expression agreed reasonably well with the measured results over the entire range of macropore volume fraction.

Zusätzliches Material: 5 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690080218

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3

Digitale Medien

Low temperature ortho-para hydrogen conversion-kinetic studies (1962)

Wakao, Noriaki ; Selwood, P. W. ; Smith, J. M.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 8 (1962), S. 478-481

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Rate studies were carried out for the ortho-para hydrogen conversion at liquid nitrogen temperature with a multiple-impregnation nickel on aluminum oxide catalyst. Data were obtained at pressures up to 400 lb./sq. in. gauge over a range of flow rates for three catalysts of different pellet sizes.For the largest particle, ⅛-in. cylinders, diffusion resistances were significant. Effectiveness factors were evaluated and found to be somewhat less that 0.5 for this relatively active catalyst. After the diffusion resistances were accounted for, the surface rate was correlated on the basis of a mechanism supposing molecular hyddrogen to be adsorbed on the surface. Separate evaluation of the catalyst for the hydrogen-deuterium exchange reaction suggested that dissociation was not significant at liquid nitrogen temperature.

Zusätzliches Material: 4 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690080411

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4

Digitale Medien

Power requirements and blend times in the agitation of pseudoplastic fluids (1962)

Godleski, E. S. ; Smith, J. C.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 8 (1962), S. 617-620

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Agitation and blending studies were made with solutions of Natrosol 250H, which were pseudoplastic fluids with nonconstant flow-behavior indexes. The published power number-Reynolds number correlation for pseudoplastic fluids having constant flow-behavior indexes is valid for Natrosol solutions. Published correlations for blend times in Newtonian fluids do not apply to Natrosol solutions; the blend times are ten to fifty times longer than with Newtonian fluids of the same apparent viscosity. Blend times are shortest in unbaffled vessels when a vortex is formed and correlate well with the vortex depths. Insertion of radial baffles always lengthened the blend time.

Zusätzliches Material: 6 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690080511

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5

Digitale Medien

Flow and diffusion characteristics of alumina catalyst pellets (1963)

Robertson, J. L. ; Smith, J. M.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 9 (1963), S. 342-347

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Steady state constant pressure diffusion measurements were made on a series of alumina pellets using the nitrogen-helium system at 1 atm. and 80°F. The pellets were prepared from the same alumina powder but compressed to different densities. Pore size distribution data indicate that all the pellets had approximately the same micropore sizes and volume, but different macropore volumes. Flow measurements with nitrogen were also carried out for the same pellets over a pressure range, up to 1 atm. The data show that the pellet density, or macropore volume, has a pronounced effectOn the basis of a simplified model of the pellet, path lengths were evaluated from the flow data. On the assumption that the diffusion path length is the same, a method is presented for predicting diffusion rates. The results so computed are independent of the path tortuosity. The method correctly evaluates the effect of pellet density on diffusion, but measured rates are 40 to 80% of the calculated values.

Zusätzliches Material: 9 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690090313

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6

Digitale Medien

Diffusion rates in porous catalysts (1961)

Henry, J. P. ; Chennakesavan, Balapa ; Smith, J. M.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 7 (1961), S. 10-12

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Rates of diffusion of helium, nitrogen, and carbon dioxide through alumina pellets were measured at atmospheric pressure and room temperature. The cylindrical pellets, ¾ in. diameter and ⅜ in. in length, were prepared from α-alumina particles with a mean pore radius of 65 Å. Surface area and pore volume data indicated that the corresponding mean pore radius of the micro and macropores in the whole pellet was 96 Å.The results showed that Knudsen type of diffusion was the controlling transport process despite the large fraction of void volume in the macropores. Carbon dioxide diffused more rapidly than expected, suggesting the possibility of migration of physically adsorbed molecules along the pore walls.The diffusion rates were about 16% higher than predicted, with a mean pore radius (Wheeler model) based upon the void volume of both micro and macropores used. However there is no logical basis for using this mean pore radius for a pellet having widely separated, micro and macropore size distributions.

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690070104

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7

Digitale Medien

Heat transfer characteristics of porous rocks: II. Thermal conductivities of unconsolidated particles with flowing fluids (1961)

Kunii, Daizo ; Smith, J. M.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 7 (1961), S. 29-34

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Experimental heat transfer studies were carried out in beds of unconsolidated glass beads and sand through which fluids were flowing. The scope of the measurements included four fluids, helium, air, carbon dioxide, and water liquid at atmospheric pressure in beds packed with four sizes of glass beads, 110, 370, 570, and 1,020 μ and with two sizes of sand, 110 and 240 μ. Flow rates ranged form 1 to 26 lb./(hr. sq.ft.) in a direction parallel and countercurrent to energy flow.The data were interpreted in terms of apparent, effective thermal conductivities of the bed. The values of ke increase significantly with mass velocity of fluid.By considering the mechanism of heat transfer in porous media a relationship was developed between ke and the heat transfer coefficient between fluid and particle. Treatment of the experimental data in this fashion, combined with available information for larger particles, results in a correlation of Nusselt and Reynolds numbers for air that covers the range NRem = 10-1 to 104.

Zusätzliches Material: 10 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690070109

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8

Digitale Medien

Burning rates of solid propellants (1960)

Smith, J. M.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 6 (1960), S. 299-304

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: A model is proposed for the burning of solid propellants which takes into account heat transfer, diffusion, and chemical reaction processes. The chemical step influencing the rate is postulated to be a reaction between a gaseous molecule and a solid component occurring at the solid-gas interface. The combination of expressions for the rates of the heat transfer, diffusion, and reaction steps leads to relatively simple equations for the burning rate in terms of (1) the physical properties of the propellant; (2) the transport coefficients; (3) the operating conditions of the burning process, temperatures, and pressure; and (4) chemical characteristics of the gas-solid reaction, activation energy, frequency factor, and heat of reaction.The well-established facts concerning burning rates, the effect of pressure and initial temperature, and the phenomenon of erosive burning are predicted by the proposed theory. Also specific experimental data for burning potassium and ammonium perchlorate composite propellants can be predicted from the theory. The values of the variables necessary to obtain agreement between observed and predicted results are generally realistic. However it should be emphasized that conclusions regarding the detailed mechanism of the burning process cannot be obtained from comparison with burning-rate data. Elucidation of the kinetic steps in the process will require experimental investigation of the intermediate products of combustion and a detailed study of the burning surface and gaseous flame zone.

Zusätzliches Material: 2 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690060225

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9

Digitale Medien

Pulsation in a fixed-bed reactor (1963)

Biskis, E. G. ; Smith, J. M.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 9 (1963), S. 677-680

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Rates of reaction were measured for the liquid phase hydrogenation of α-methyl styrene in a pulsed, fixed bed reactor. Data at 80 psia and 55°C., using 0.5 wt. % palladium on ⅛″ Al2O3 spheres as a catalyst, indicated that the mass transfer of dissolved hydrogen to the catalyst surface controlled the rate of conversion of styrene to cumene. Hence the data were employed to calculate mass transfer coefficients as a function of pulse frequency and amplitude.Comparison with non-pulse data at the same Reynolds number showed that pulsation increased the mass transfer rate as much as 80%.

Zusätzliches Material: 6 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690090520

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10

Digitale Medien

Diffusion and reaction in porous glass (1964)

Rao, M. Raja ; Smith, J. M.

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 10 (1964), S. 293-297

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ISSN: 0001-1541

Schlagwort(e): Chemistry ; Chemical Engineering

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung

Notizen: Constant pressure diffusion rates of hydrogen through Vycor porous glass were measured in nitrogen and neon systems. The experimental diffusivities are less than those predicted by the random pore model indicating that this model may not be satisfactory for a low porosity material such as Vycor. Interpreted in terms of an assembly of parallel pores the data suggest a tortuosity factor of approximately 2.4.Rate data for the ortho-para hydrogen reaction were also measured at -196°C. and 1 atm. The catalyst 2% nickel/Vycor was found to have pore properties (area, mean pore size, pore volume) similar to that of plain Vycor. Predicted effectiveness factors using the experimental diffusion data were in good agreement with values determined experimentally. The latter were evaluated from rate measurements on both pellet and particles (58 μ mean diameter).

Zusätzliches Material: 3 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/aic.690100305

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