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  • 1955-1959  (8)
  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 177 (1956), S. 126-127 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] IN a previous paper we reported the isolation from technical e-caprolactam polymerizates of three individual crystalline substances (designated here as A, B and C) having identical elementary composition (OaHnON) and containing no free NH2 or COOH groups1. They obviously represent cyclic oligomers ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 177 (1956), S. 127-128 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] THE intermediate products formed in the hydrolysis of the cyclic oligomers of ϵ-caprolactam and some linear oligomers of ϵ-aminocaproic acid (in a large excess of 25 weight per cent hydrochloric acid at 110°) have been identified and semi-quantitatively determined. A paper ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 28 (1958), S. 246-249 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die kritischen Bemerkungen von H. YUMOTO und N. OGATA1 zu einer früheren Abhandlung aus unserem Laboratorium2, in der eine experimentelle Bestätigung gebracht wurde für die Anwendbarkeit der Annahme einer gleichen Reaktivität der Endgruppen nach FLORY-SCHULZ auf Gleichgewichtspolymere des Nylon 6, werden zurückgewiesen.Es wird gezeigt, daß überhaupt keine Diskrepanz zwischen den Resultaten der beiden Laboratorien besteht. Die von den japanischen Autoren gefundenen Abweichungen beziehen sich auf Systeme mit extrem hohem Wassergehalt und sehr niedrigem Durchschnittspolymerisationsgrad (P̄n zwischen 1.3 and 6).Diese Beobachtungen liegen also außerhalb des von uns untersuchten Gebietes zwischen P̄n = 60 bis 14, für das unsere Ergebnisse ausschließlich beansprucht wurden. Sie können sogar mit einer Extrapolation der letzteren gut übereinstimmen.
    Notes: The critical comments of H. YUMOTO and N. OGATA1 on a previous paper from this laboratory2, in which experimental evidence was given that the FLORY-SCHULZ assumption of equal reactivity is applicable to Nylon 6 equilibrium Polymers, are rejected.It is shown that there is no question of a discrepancy between the results of the two laboratories.The deviations found by the Japanese authors apply to extremely high water contents and very low degree of polymerisation (P̄n between 1.3 and 6). They have no bearing on the range of P̄n between 14 and 60 for which our results were claimed and may even be well in accord with an extrapolation of the latter.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 30 (1959), S. 154-168 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Hydrolyse in 7.72 N Salzsäure bei 110°C. der cyclischen Di-, Tri und Tetraamide des ε-Caprolactames und des cyclischen Diamides aus Hexamethylendiamin und Adipinsäure wird kinetisch untersucht. Die bei der Reaktion auftretenden Zwischenproduckte wurden auf chromatographischem Wege identifiziert und beweisen die Konstitution der betreffenden cyclischen Verbindungen.Für den auffallenden Unterschied in der Hydrolysegeschwindigkeit der beiden isomeren cyclischen Diamide konnte auf Grund bekannter Strukturprinzipien keine einfache Erklärung gegeben werden.
    Notes: A kinetic investigation is offered of the hydrolysis in 7.72 N aqueous hydrochlorie acid at 110°C. of the cyclic di-, tri- und tetraamides of ε-caprolactam and of the cyclic diamide from hexamethylene diamine and adipic acid. The intermediates of the reaction, identified by chromatography, provide definite proof of the constitution of these cyclic compounds.For the remarkable difference between the rate constants of the two isomeric cyclic diamides no simple explanation could be given on known structural grounds.
    Additional Material: 5 Ill.
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  • 5
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The validity of the Flory-Schulz distribution of chain length in equilibrium polymers produced from ∊-caprolactam and water (Nylon 6) over a DP range from ∼14 to ∼90 is tested by determination of the content of monomer (∊-aminocaproic acid, ACA) by means of a chromatographic technique. Experiments show general agreement with a simple theoretical relationship (P̄n1 = N, where P̄ = number average DP of chains, n1 = number of ACA molecules, and N = total number of chains), required for equilibrium if equal reactivity of all functional groups independent of chain length is assumed. Moderate deveiations from this relation, which seem to occur at higher DP values (P̄ ∼ 90) require further investigation.
    Additional Material: 1 Ill.
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  • 6
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Kinetic runs were performed at two temperatures with ∊-caprolactam-water mixtures containing from 5 to 10 mole-% of water. The concentrations of unconverted lactam x and endgroups c were determined, and in some cases also the concentration of aminocaproic acid u1 and the quantity of cyclic oligomers formed. The concentration of water w and that of the amide groups in linear molecules were calculated from the boundary conditions. In the evaluation of the kinetics of the reaction, which run towards an equilibrium state, values of the equilibrium constants from previous determinations were used. The course of c can be satisfactorily fitted in with the picture of hydrolysis of the lactam, followed by polycondensation. The former starts off as an uncatalyzed reaction between lactam and water but is soon dominated by hydrolysis catalyzed by endgroups. The quantity of lactam thus converted appears to be only a small fraction of the total lactam conversion. If it is assumed that the bulk of lactam disappears through a reaction with rate proportional to xc2, satisfactory fit with the experiments is obtained. This reaction is interpreted as an endgroup catalyzed polyaddition, i.e., an addition of lactam onto an endgroup of a linear molecule catalyzed by another endgroup. From the determinations of aminocaproic acid concentration u1, confirmatory evidence can also be derived that conversion of this linear monomer is for the major part due to an endgroup catalyzed reaction with lactam of a rate proportional to xu1c and with a rate constant of the same magnitude as that pertaining in the general polyaddition reaction. It is argued that the existence of polyaddition also requires transamidation reactions between linear molecules in which one chain with its endgroup reacts with an amide group of a second chain under formation of two other chains of different lengths. This reaction will tend to produce random chain lengths and will thus accelerate the attainment of a normal Flory-Schulz MW distribution in the reaction product. The rate of formation of cyclic oligomers during polymerization is also in line with the assumption that these substances are mainly produced by a transmidation reaction of a chain endgroup with an amide group of the same chain, rather than by cyclic condensation of a chain of the required length. A survey of rate constants is given. There is general agreement with those given by Wiloth.
    Additional Material: 9 Ill.
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  • 7
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This paper reports on quantitative measurements of the small angle scattering of various rayons and ramie fibers as functions of moisture content using a three slit vacuum camera and monochromatic radiation. The scattered intensity was normalized on sample thickness and primary intensity through determination of the absorbance of the sample and of the intensity of the transmitted beam measured in arbitrary units. From these data the scattering power as defined by Porod, being the mean square of the fluctuations of the electron density, was calculated. This quantity was then converted into electron units through calibration of the procedure with exposures of noble metal sols of known composition and thus of computable scattering power. The exprimental results were compared with the scattering power calculated for cellulose fibers when regarded as submicro tow-phase systems consisting of crystalline cellulose imbedded in a homogeneous mixture of noncrystalline cellulose and water. In the air-dry state a few of the rayon speciman examined exhibited a scattering power of magnitude consistent with theory. The majority yielded much higher values, up to six times larger (so does dry ramie). This is interpreted by the occurrence of submicro voids to a volume fracton of less than 0.75%, variable from fiber to fiber. This explanation is corroborated by the existenc of a distinct correlation between scattering power and gravimetric density of the fiber. In conclusion, microvoids are the principal scattering “particles” in dry fibers. The values of the scattering power of water swollen rayons and ramie can be interpretated on the basis of a three-pahse model, with the phases consisting of crystalline cellulose, a homogeneous mixture of amorphous cellulose with water, and water, respectively.
    Additional Material: 6 Ill.
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  • 8
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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