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  • Chemistry  (7)
  • ddc:330
  • 1955-1959  (7)
  • 1
    Electronic Resource
    Electronic Resource
    Rates of flow through microporous solids (1958)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 4 (1958), S. 90-96 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690040117
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of superatmospheric pressures on nucleate boiling of organic liquids (1958)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 4 (1958), S. 102-113 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Superatmospheric pressures greatly reduce the temperature differences in nucleate boiling of or ganic liquids. Since nucleate boiling is characterized by bubble formation at the heating surface, it seems logical to investigate the pressure difference that causes bubble formation. It has been found that for organic liquids the difference in vapor pressure corresponding to the temperature difference behaves in a regular manner with pressure but does not vary greatly. This regular behavior permits prediction of temperature differences at higher pressures with a knowledge of only vapor-pressure and boiling data at one pressure. New boiling data have been obtained in the investigation.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690040119
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  • 3
    Electronic Resource
    Electronic Resource
    Polyesters of hydroxybenzoic acids (1959)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 2 (1959), S. 198-202 
    Details
    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: Polymers and copolymers were prepared from the acetoxy derivatives of m- and p-hydroxybenzoic acids. Molecular weights of over 20,000 were obtained for poly(m-hydroxybenzoic acid) and copolymers containing up to 60% para isomer. These polyesters were crystalline, and the degree of crystallinity increased as the para isomer content was increased. Blocks of the high-melting, insoluble poly(p-hydroxybenzoic acid) tend to form in copolymers containing a high proportion of the para isomer because of the difference in reactivity of the two isomers. Copolymers containing at least 55% of the meta isomer are soluble in several classes of solvents. The copolymers do not have sharply defined melting points, but have softening temperatures ranging from 150°C. to over 300°C. Tensile strengths of approximately 10,000 psi and elongations of about 6% to 40% were obtained. The polymers were relatively stable to oxidative degradation, but not to hydrolysis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1959.070020512
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  • 4
    Electronic Resource
    Electronic Resource
    Transitions in plasticized and unplasticized cellulose acetatesThe work reported in this paper comprises a part of a program of research on the physical structure and properties of cellulose derivatives carried out in the Department of Chemistry, Cornell University, and supported by the Allegany Ballistics Laboratory, Cumberland, Maryland, an establishment owned by the United States Navy and operated by Hercules Powder Company under Contract NOrd 10431. (1957)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 25 (1957), S. 77-96 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The temperature-dependence of specific volume, rigidity modulus, and mechanical losses of plasticized and unplasticized cellulose acetates in the temperature range -100 to +200°C. has been studied. Two cellulose acetates, a triacetate and a cellulose (2.2) acetate were used, these being plasticized with varying amounts of either benzyl acetate, m-cresol, o-ethylphenol, γ-butyrolactone, monomethylaniline, benzylphenol, or Santophen 7 (a phthallyl glycolate). The specific volume measurements, made using an extremely sensitive dilatometer, indicated three apparent second-order transitions and one first-order (melting) transition in cellulose triacetate and three or possibly four apparent second-order transitions but no first-order transition in the cellulose (2.2) acetate. Both the first-order and second-order transitions were depressed by the addition of plasticizer, the depression being most marked with the phenolic-type plasticizers. Because of polymer decomposition at temperatures above 200°C., it was not possible to study the melting of mixtures containing less than 30% plasticizer and subsequently no reliable values for the melting temperature, the entropy, and the heat of crystallization could be determined. Rigidity modulus measurements, obtained using a torsional pendulum technique and the mechanical loss (damping) measurements, confirmed the existences of these second-order transitions in both acetates and indicated that only the highest temperature transition, 175°C. in the triacetate and 195°C. in the secondary acetate, had the characteristics of a normal glass to rubber transition.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1957.1202510807
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  • 5
    Electronic Resource
    Electronic Resource
    Phosphorus-containing polymers by a tiwo-phase condensation (1959)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 35 (1959), S. 540-541 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1959.1203512924
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  • 6
    Electronic Resource
    Electronic Resource
    Swelling and absorption by cellulose acetate in binary solvent-hexane mixtures (1955)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 18 (1955), S. 63-86 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Preferential absorption and swelling by cellulose acetate in binary solvent-type liquid/hexane mixtures has been studied at 25°C. Secondary cellulose acetate, of acetic acid yield 53.7%, was used in fibrous form and as film. Triacetate, prepared by nondegradative acetylation of the secondary, was also used. Factors affecting preferential absorption by the fibrous secondary acetate seem to include the activity of the solvent-type liquid and its chemical type, the swelling power of the mixture, and steric effects. Preferential absorption of ketones and esters other than methyl formate appears to be independent of both acetyl content and structure. Absorption of methyl formate, acetic acid, and heterocyclic bases by the triacetate is less, at all concentrations, than by the secondary acetate. At low concentrations cresols and chlorinated hydrocarbons are absorbed to a smaller extent by the triacetate but at higher concentrations the reverse is the case, such variations in absorption being ascribed to steric effects and to the elimination of hydroxyl groups on complete esterification. Absorption by the secondary acetate films also suggests steric effects. Comparison of the measured weight of films with that estimated from the change in composition of the mixture following absorption, assuming no hexane to be absorbed, Suggests that this assumption is true at low concentrations. At higher concentrations, leading to high degrees of swelling or to gelatinization, the mixture seems to be imbided. There is no general relationship between swelling and the δ value of the solvent-type liquid but δ values for the mixtures just causing complete solution of the acetates are not very different when the mixtures involve solvents of similar chemicals type.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1955.120188706
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  • 7
    Electronic Resource
    Electronic Resource
    Factors influencing removal of pentosan from birch wood: Evidence on the lignin-carbohydrate bondThis article is abstracted from a portion of a thesis submitted by Russell Nelson in partial fulfillment of the requirements for the degree of Doctor of Philosophy and is the ninth in a series from this laboratory on the structure of lignin. (1956)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 22 (1956), S. 435-448 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of particle size, alkali concentration, and temperature on the rate of extraction of pentosans and on the amount of pentosans extractable from birch wood meal has been studied. In general, a very rapid extraction of accessible pentosans is followed by a slow, almost negligible, diffusion of inaccessible pentosans. There is, therefore, almost a limiting amount of pentosans not extractable under each given set of conditions. The effect of decreasing particle size is to increase the amount of pentosan extractable under any given set of conditions. The optimum sodium hydroxide concentrations at 0, 20, 40, 60 and 80 degrees are about 2, 4, 7, 10 and 12%, and under the last of these conditions at least 80% of the pentosans can be extracted rapidly from the wood meal. Pentosan is made more accessible by increasing the alkali concentration up to these levels, but thereafter the amount of accessible pentosan is decreased by an increase in alkali concentration. The decrease in extractability has the same concentration and temperature dependence as the increase in cellulose swelling under the same conditions. Therefore, pentosan removal is inhibited by excessive swelling restricted within the rigid lignin and fiber structure. Similar but less marked inhibition by swelling occurs even after lignin removal.Even under conditions of low alkali concentration, when no inhibition of solution by restricted swelling occurs, neither the temperature nor alkali dependence of rate is typical of a chemical process. The factors which inhibit the removal of pentosan are therefore physical and the inhibition of solution of pentosan from birch wood gives no support to the concept of a lignin-carbohydrate bond.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1956.1202210209
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