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  • Wiley-Blackwell  (10)
  • Blackwell Science Inc
  • German Medical Science GMS Publishing House; Düsseldorf
  • 1955-1959  (9)
  • 1915-1919  (1)
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  • 1
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chain-like polyphosphates may be regarded as cation-exchangers. The exchange-properties with organic cations are similar to those of layer-silicates, e.g. montmorillonite, or to those of uranium-micas.With bulky quaterny alkylammonium- or alkylpyridinium ions two dimensional swelling occurs in polar liquids (alcohols, ethers, esters, ketones …) changing the distance of the chains reversibly.With mono-n-alkyl- and arylammonium ions the polyphosphate-chains are linked together by hydrogen-bonds, thus forming two-dimensional layers no longer capable of intracrystalline swelling.
    Notes: Die Annahme von THILO und RATTAY, daß die Enthärtung von Wasser mit Polyphosphaten als Ionenaustauschreaktion aufzufassen ist, konnte durch den Austausch der K+-Ionen von kettenförmigem Kaliumpolyphosphat gegen große organische Kationen erhärtet werden. Das Kaliumpolyphosphat zeigt mit diesen Ionen ähnliche Austauschereigenschaften, wie die Schichtsilicate Montmorillonit und Muskowit oder wie die Uranglimmer.Nach dem Eintausch großer quartärer Alkylammonium- oder Alkylpyridinium-Ionen kann kettenförmiges Polyphosphat mit Alkoholen, Äthern, Ketonen, Estern, aromatischen Kohlenwasserstoffen und Nitroverbindungen zweidimensional innerkristallin quellen. Makroskopisch zeigt sich diese Quellung in der Bildung viskoser Lösungen oder zäher Gallerten mit diesen Flüssigkeiten.Mit primären und sekundären Alkyl- oder Arylammoniumionen tritt keine zweidimensionale innerkristalline Quellung auf, weil die Polyphosphatketten mit diesen Ionen über Wasserstoffbrückenbindungen zu Schichten vernetzt werden. Da ein Teil der O-Atome der Polyphosphatketten in diesen Schichten praktisch ebene Sauerstoff-Sechsringe bilden, ist für die trigonalen Ionen R—NH3+ die Möglichkeit zur Ausbildung von Wasserstoffbrückenbindungen besonders günstig. Die Bedeutung von H-Brückenbindungen wird betont durch das Verhalten der Polyphosphate mit Hexamethylen- und Dekamethylen-(α, ω)-diammoniumionen einerseits und Hexamethylen- bzw. Dekamethylen (α, ω)-bis-trimethylammoniumionen andererseits.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 19 (1956), S. 583-585 
    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
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  • 3
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In order to establish the general solubility rules for graft copolymers, a first theory has been proposed from data in the literature and from our own results, a experimental basis is given for a more advanced theory. Two limited cases have been considered; (a) The polymers are perfectly miscible, (b) both polymers are completely incompatible. In case (a) the solubility coefficient of the graft copolymers is an arithmetic means of those of the corresponding homopolymers. In case (b) it is impossible to attribute a solubility coefficient to the graft copolymer, and in some cases, the copolymers with an intermediate degree of grafting should be insoluble. The separation of graft copolymers PVC-PAN, PVC-PMMA, PVC-PAN, and PI-PS from their homopolymers was studied and the results discussed on the basis of this theory. In the case of the graft copolymer PI-PS, although both polymers are incompatible, the difference between the solubility coefficients is sufficiently low so that the behavior of this graft copolymer is analogous to case (a) and it is possible to evaluate the degree of grafting from the limits of precipitation. The experimental results of different authors, related to the solubility of graft copolymers, are discussed.
    Notes: Afin d'établir des régles générales de solubilité des copolymères greffés, nous proposons une ébauche de théorie et nous essayons de dégager, à partir de nos résultats et des données bibliographiques existantes, une base expérimentale pour une théorie plus perfectionnée. Les deux cas limités suivants sont envisagés:(a) Les polymeères sont parfaitement miscibles; (b) les deux polymères sont complètement incompatibles.Dans le cas (a), le coefficient de solubilité des copolymères greffés est une moyenne arithmétique de ceux des homopolyméres correspondants. Dans le cas (b), il est impossible d'attribuer au copolymère greffé un coefficient de solubilité et dans certaines conditions, les copolymères de taux de greffage intermédiaire devraient ětre insolubles. La séparation des copolymères greffés PVC-PAN, PVC-PMMA, PVC-PAN et PI-PS des homopolymères est étudiée et les résultats discutés à la lumière de la théorie cidessus. Dans le cas du copolymère greffé PI-PS, bien que les deux polymères constituants soient incompatibles, l'écart entre les coefficients de solubilité est suffisamment petit pour que son comportement se rapproche du cas (a) et il est possible d'évaluer le taux de greffage à partit des limites de précipitation. Les résultats expérimentaux de différents auteurs, relatifs à la solubilité des copolymères greffé sont également discutés.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 16 (1955), S. 491-504 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: An attempt is made to apply the usual kinetic scheme (initiation, propagation, mutual termination) to polymerizations in precipitating media, by simply assuming that the stationary state hypothesis cannot be applied in this case, because of a strong decrease of the termination rate. The integration of the set of differential equations is carried out for two cases: (a) concentration of the catalyst is kept constant all through the polymerization (eq. 5a); (b) the catalyst disappears by a first order reaction (eq. 5b). The resulting equations can be easily handled only in the first case. An approximation procedure is proposed to take into account the disappearance of the catalyst and the accumulation of the catalyst in the monomer phase which becomes important at higher degrees of conversion if the catalyst is insoluble in the polymer. The equations obtained are used to analyze the experiments of Bengough and Norrish and of Schindler and Breitenbach at various temperatures and catalyst concentrations. The results are highly satisfactory (Figs. 1 and 2) and the log kp/kt and log (kaA0kt)-1/2 vs (1/T) plots lead to straight lines, corresponding to Ep≠ - Et≠ = 5.2 kcal./mole; Ea≠ + Et≠ = 29.5 kcal./mole (Fig. 3). These values indicate that the activation energy for the termination step cannot be very high. The slowing down of the reaction is hence due to a decrease of the frequency factor. The constants determined from experiments at low conversion rates are then used to make a priori calculation with the help of the approximation method indicated above, of the conversion rates as a function of time under the conditions of temperature and catalyst concentration used by Schindler and Breitenbach and by Prat. The theoretical curves are compared with the experimental data in Figures 4 to 6. Here again the agreement can be considered as satisfactory. It is also possible to represent with the same formula the data of Bengough and Norrish on BPO catalyzed polymerization of vinylidene chloride at 47° and data of Burnett and Melville on the photochemical polymerization of the same compound at 25°C. The ratio of kp/kt is smaller in this case than for vinylchloride. Combining the results of Bengough and Norrish on the two monomers and assuming that the decomposition rate of BPO is the same in the two monomers one obtains: \documentclass{article}\pagestyle{empty}\begin{document}$ \begin{array}{*{20}c} {\frac{{k_p ({\rm vinylidene})}}{{k_p ({\rm vinyl})}} = 2.6;} & {\frac{{k_t ({\rm vinylidene})}}{{k_t ({\rm vinyl})}} = 0.7.} \\ \end{array} $\end{document} Using the measurements of Burnett and Melville of the initiation rate one can also calculate the absolute values of kp and kt for vinylidene chloride at 25°C. However, the combination of the results at 25 and 47°C. leads to an abnormally high activation energy Ep≠ - Et≠ = 26 kcal., which suggests that some other phenomena take place. These difficulties, as well as some disagreements in details concerning the PVC polymerization, together with the observation that other polymerizations in precipitating media cannot be described with the same formula, lead us to believe that although the general approach is sound, the real situation is more complex. Until the objections are overcome equation (5a) is to be considered as a semiempirical formula, applicable to PVC polymerization rather than completely representing the reality.
    Notes: Une tentative est faite d'utiliser pour la description de la polymérisation en milieu précipitant le schéma cinétique habituel (amorçage, propagation, terminaison mutuelle), mais en admettant que l'état quasi-stationnaire n'est pas atteint au début de la réaction. Le système d'équations différentielles pu être résolu pour certains cas: concentration constante de catalyseur, concentration décroissante selon une loi cinétique de premier ordre, etc…. Une méthode d'approximation est proposée pour traiter les cas où il y a accumulation du catalyseur dans la phase monomère par suite de son insolubilité dans le polymère. Les formules obtenues permettent de rendre compte de la polymérisation en masse du chlorure de vinyle, à différentes températures et à différentes concentrations du catalyseur (peroxyde de benzoyle), et ceci aussi bien pour des expériences à faibles degrés de conversion que pour des expériences poussées à des degrés de conversion élevés. Les constantes kp/kt et (kaA0kt)-1/2, déterminées à différenctes températures correspondent à des énergies d'activation Ep≠ - Et≠ = 5,2 kcal., Ea≠ + Et≠ = 29,6 kcal. Cette dernière valeur indique que l'énergie d'activation de terminaison n'est pas très élevée et que le ralentissement de terminaison observé est dû à une diminution du facteur de fréquence. Les mêmes formules ont été utilisées pour le cas de polymérisation du chlorure de vinylidène. Dans ce cas il a été possible de calculer les valeurs absolues des constantes de vitesse de terminaison et de propagation qui sont très sensiblement plus faibles que dans le cas de polymérisation en milieu homogène. Certaines difficultés persistent, qui amènent à penser que la théorie n'est pas complète.
    Additional Material: 7 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 18 (1955), S. 586-588 
    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.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 7
    ISSN: 0095-9898
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
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  • 8
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tertiäre Mannich-Basen des Indols, Acetophenons, Cyclohexanons, β-Naphthols und Nitromethans bzw. deren quartäre Salze reagieren mit Phenylhydroxylamin unter Aminogruppen-Austausch zu N-substituierten Phenylhydroxylaminen. Diese Hydroxylamine lassen sich nach bekannten Methoden leicht zu Phenylnitronen dehydrieren, die man weiter zu Aldehyden verseifen kann.
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 2 (1956), S. 62-64 
    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 wide applicability of the Langmuir-Hinshelwood classical kinetics to surfaces which are known to depart strongly from ideal Langmuir behavior is a well-known paradox of surface catalysis. The applicability and limitations of the classical method are illustrated by means of a simple reaction. The generality of the method is demonstrated by its applicability to ammonia synthesis with and without water vapor. The limitations are often more than compensated for by the added insight into reaction mechanism which it can provide without unded complexity. A three-step approach to surface kinetics is suggested and discussed.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 2 (1919), S. 266-276 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
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