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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 115 (1968), S. 234-244 
    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: Allylvinylsulfonat (AES) wurde durch radikalische Initiatoren unter verschiedenen Bedingungen polymerisiert. Die Polymeren enthalten 67 bis 86% cyclischer Grundbausteine, wenn die Monomerkonzentration zwischen 8,9 mol/l (Substanzpolymerisation) und 0,28 mol/l liegt. Der Anteil der Allylgruppen, der an der Polymerisation teilnimmt, ist viel höher, als man erwarten sollte auf Grund der Zusammensetzung der Copolymeren, die man aus Propylvinylsulfonat und Allyläthansulfonat erhält. Die Allylgruppe von AES wird in die Polymerkette ausschließlich über einen Cyclopolymerisationsmechanismus eingebaut.AES wurde mit Styrol, Methylacrylat und Vinylacetat copolymerisiert. Es wurden folgende Parameter gefunden: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {\begin{array}{*{20}c} {\begin{array}{*{20}c} {{\rm r}1({\rm AES})0.23 \pm 0.03;{\rm r}2({\rm styrene})} \\ {{\rm r1(AES)}0.07 \pm 0.02;{\rm r2(methyl}\,{\rm acrylate})} \\ {{\rm r1(AES)}3.6 \pm 0.2;{\rm r2(vinyl}\,{\rm acetate})} \\ \end{array}} \\ \end{array}} & {\begin{array}{*{20}c} {1.6 \pm 0.1} \\ {10.7 \pm 0.2} \\ {0.38 \pm 0.08} \\ \end{array}} \\ \end{array} $$\end{document} Der Prozentgehalt cyclischer Grundbausteine ist in Copolymeren mit Methylacrylat und Styrol niedrig, aber in Copolymeren mit Vinylacetat hoch. Bei der Copolymerisation mit Styrol bzw. Methylacrylat ist die Reaktivität von AES etwa die gleiche wie bei Bytylvinylsulfonat; bei der Copolymerisation mit Vinylacetat ist AES reaktiver als Butylvinylsulfonat. Dieser Anstieg der Reaktivität wird der Bildung cyclischer Radikale zugeschrieben. AES ist ein weiteres Beispiel fiir ein unsymmetrisches 1.6-Dien, in welchem die Reaktivität der weniger reaktiven Doppelbindung größer ist als in analogen Monomeren, in welchen nur diese eine Doppelbindung vorkommt.
    Notes: Allyl ethenesulfonate (AES) has been polymerized by radical initiators under different conditions. The polymers consist of 67 to 86% of cyclic recurring units for monomer concentrations going from 8.9 (bulk) to 0.28 mole·1-1. The amount of allyl groups taking part in the polymerization is much higher than expected from the composition of copolymers obtained from propyl ethenesulfonate and allyl ethanesulfonate. The allyl group of AES is incorporated in the polymer chain only via the cyclopolymerization mechanism.AES has been copolymerized with styrene, methyl acrylate, and vinyl acetate. The folowing copolymerization parameters were found: \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {\begin{array}{*{20}c} {\begin{array}{*{20}c} {{\rm r}1({\rm AES})0.23 \pm 0.03;{\rm r}2({\rm styrene})} \\ {{\rm r1(AES)}0.07 \pm 0.02;{\rm r2(methyl}\,{\rm acrylate})} \\ {{\rm r1(AES)}3.6 \pm 0.2;{\rm r2(vinyl}\,{\rm acetate})} \\ \end{array}} \\ \end{array}} & {\begin{array}{*{20}c} {1.6 \pm 0.1} \\ {10.7 \pm 0.2} \\ {0.38 \pm 0.08} \\ \end{array}} \\ \end{array} $$\end{document} The percentage of cyclic recurring units is low in copolymers with methyl acrylate and with styrene but is high in those with vinyl acetate. In the copolymerization with styrene and with methyl acrylate the reactivity of AES is about equal to that of butyl thenesulfonate; in the copolymerization with vinyl acetate it shows a much higher reactivity than butyl ethenesulfonate. This increase in reactivity is attributed to the formation of cyclic radicals. AES is another example of an unsymmetrical 1.6-diene wherein the reactivity of the less reactive double bond is greater than that observed in analogous monomers where only that double bond is present.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 19 (1968), S. 782-785 
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Simple method for the potentiostatic determination of teh pitting potential in one single experimentA simple and fast method is described for the determination of the pitting potential of stainless steels. By using wire electrodes to which a constant DC-potential is applied one may scan potential ranges of any size in one single experiment. Tests with four autenitic steels in 1 N NaCl have shown that addition of Mo and Si displaces the pitting potential to higher values at room temperature; at higher temperature, however, this effect vanishes. Addition of NaBr and NaJ to the NaCl-solution produces a considerable increase of the pitting potential of Mo-free stainless steels. The experimental principle can be used also for the investigation of stress corroison cracking.
    Notes: Es wird eine einfache und schnelle Methode zur Ermittlung des ochfraßpotentials von nichtrostenden Stählen beschrieben. Durch die Verwendung von Drähten als Meßelektroden, an die eine festliegende gleichspannung angelegt wird, kann in einem einzigen Versuch ein beliebig großer Potentialbereich geprüft werden. Versuche mit 4 austenitischen Stählen in 1 n NaCl zeigen, daß Mo und Si das Lochfraßpotential bei Raumtemperatur anheben; dieser Effekt geht jedoch bei höherer Temperatur verloren. Zusäte von NaBr und NaJ zur NaCl-Lösung führen zu einer beträchtlichen Zunahme des Lochfraßpotentials von molybdänfreien nichtrostenden Stählen. Das Versuchsprinzip kann auch zur Unter suchung von Spannungskorrosion verwendet werden.
    Additional Material: 6 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 299-306 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The predominant role of van der Waal interactions in determining the helical conformations of a simple synthetic linear polymer, as well as helical polypeptides, was pointed out in systematic studies by Liquori et al.1,2. In the case of homopolypeptides the conformational analysis carried out on the basis of a simple semiempirical function describing the van der Waal pairwise interactions between the non directly bonded atoms lead to the conclusion that only five helices are allowed (Rα, β, γ, δ, Lα).2,3In view of the close similarities with poly-L-alanine, we have investigated by x-ray and conformational analysis the molecular conformation of poly(S-lactic acid) which has recently been described by Kleine and Kleine4 and Schuls and Schwaab5 and studied in solution by Goodman and D'Alagni.6 In fact, this polymer may be related to the polypeptide by the interchange of a peptide bond with ester bond along the main chain. This operation is expected to involve only a relatively small change in the steric interaction within the possible helical conformation, but obviously rules out any possibility of hydrogen bonding.
    Additional Material: 8 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 6 (1968), S. 715-729 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: At low temperatures a single strand of dAT copolymer tends to form a double helix with a loop at one end (hairpin). At slightly higher temperatures a branched structure (consisting of many hairpins connected by coiled regions) appears. The equilibrium properties of this branched structure are studied here by a propagator method. In particular the radius of gyration RG is calculated; under typical conditions, RG is expected to show a minimum at a temperature slightly below melting, in agreement with viscosity measurements. The present calculation is restricted to rather sharp transitions, for which the size of each helical region is large, even at the melting point. Then, in a rather broad range of molecular weights, M, RG is proportional to M1/4(as in the Zimm-Stockmayer theory of simple branched polymers).
    Additional Material: 10 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Letters 6 (1968), S. 547-550 
    ISSN: 0449-2986
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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