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  • 1
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 2-(9-Carbazolyl)ethyl vinyl ether (1), a known vinyl monomer, was synthesized using a phasetransfer catalyst, and homopolymerized with BF3OEt2 or EtAlCl2.2-(9-Carbazolyl)ethyl 1-propenyl ether (2) was synthesized by transetherification of ethyl 1-propenyl ether with 9-(2-hydroxyethyl)carbazole in a yield of 34% as a mixture of 49% cis and 51% trans isomer. It was homopolymerized in 90% yield with EtAlCl2 in toluene at -25°C. Copolymerization of 1 or 2 with ethyl vinyl ether (3) were initiated with BF3OEt2 or EtAlCl2. The yields of copolymers were 78-93%, depending on the polymerization conditions. The solubility of both homo- and copolymers was found to be poor. The glass transition temperatures of poly(1-co-3) and poly(2-co-3) are much lower, than those of poly(1) and poly(2).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1173-1180 
    ISSN: 0887-624X
    Keywords: chemical composition distribution ; liquid chromatography ; porous polymer beads ; HPLC ; monodisperse particles ; poly(isobutylene-co-4-methylstyrene) ; bromination ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High-performance liquid chromatography (HPLC) has been used to complement size-exclusion (gel permeation) chromatography (SEC) for the characterization of functional polymers. Whereas SEC is unable to detect compositional changes, HPLC in an appropriate interacting medium can provide detailed information on compositional changes occurring during chemical modification of a polymer. The method has been demonstrated using a normal-phase column consisting of porous monodisperse 10 μm poly(2,3-dihydroxypropyl methacrylate-co-ethylene dimethacrylate) beads that have a homogeneous coverage of aliphatic hydroxyl groups for the analysis of brominated poly(isobutylene-co-4-methylstyrene). Differences of well below 1 mol % of bromomethylstyrene units are easily detected and quantified. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1173-1180, 1997
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    International journal of fracture 84 (1997), S. 159-173 
    ISSN: 1573-2673
    Keywords: fracture ; fatigue ; polyethylene ; crack propagation ; accelerated failure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Correlation in mechanisms and kinetics of step-wise fatigue crack propagation in polyethylene pipe specimens of different geometries is studied experimentally. It is shown that crack propagation in a non-standard specimen cut from a real pipe and conserving the pipe geometry can be effectively simulated using a standard compact tension specimen. Good correlation in both kinetics of step-wise crack propagation and fractography between the specimens is achieved if experimental conditions are chosen to assure equal values of (a) stress intensity factor and (b) stress intensity factor gradient at the initial notch tips. These results extend previous technique of fatigue accelerating slow crack growth used to predict lifetime of polyethylene pipes.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 215 (1994), S. 1-10 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Gruppe neuer phenolischer Antioxidantien wurde synthetisiert und charakterisiert;ihr Einfluß auf die Polymerverarbeitung wurde an Polymerschmelzen bei wiederholter Extrusion unterucht. Die Äanderung des Schmelzflusses wurde gemessen und mit dem Verhalten bei Verwendung handelsüublicher Antioxidantien verglichen. Die untersuchten Verbindungen waren alle aus dem gleichen Phenylsegment aufgebaut, unterschieden sich aber in der Läange der para-Substituenten, die das Verhalten der Antioxidantien in Polymeren und somit ihre Wirkung entscheidend beeinflussen.
    Notes: A group of phenolic antioxidants was synthesized, characterized and the performance of these antioxidants in polymer processing was tested in the polymer melt by multiple extrusions. The change in melt flow was observed and compared with the change in melt flow by use of commercially available antioxidants. All the antioxidants examined had the same phenolic stabilization moiety but varied in the size of the substituents in the para-position of the aromatic ring. Increasing length of the side chain considerably influences the behaviour of the antioxidants in the polymer and thus their effectiveness.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2355-2369 
    ISSN: 0887-6266
    Keywords: fracture ; fatigue ; polyethylene ; molecular weight distribution ; short chain branch content ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Stepwise fatigue crack propagation in a range of polyethylene resins, some of which are candidates for use in pipes for natural gas distribution, was studied. Examination of the effect of molding conditions on fatigue crack propagation in a pipe resin indicated that fast cooling under pressure produced specimens with the same crack resistance as specimens taken from a pipe extruded from this resin. The mechanism of stepwise crack propagation in fatigue was the same as reported previously for creep loading. Observations of the region ahead of the arrested crack revealed a complex damage zone that consisted of a thick membrane at the crack tip followed by a main craze with subsidiary shear crazes that emerged from the crack tip at an angle to the main craze. The effects of molecular parameters, such as molecular weight, comonomer content, and branch distribution, on the kinetics of fatigue crack propagation were examined. Correlation of creep and fatigue crack resistance made it possible to relate fatigue fracture toughness to molecular parameters by invoking concepts of craze fibril stability developed for creep. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2355-2369, 1998
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 6
    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: Polypropylene's high processing temperatures initiate thermal oxidative degradation and loss of physical properties. Antioxidants protect polymers through the severe conditions of processing and fabrication and also through end use. Small amounts of antioxidants like 2,6-di-tert-butyl-4-methylphenol and 2[(3,5-di-tert-butyl-4-hydroxyphenyl)methylenel]-hydrazine carbothioamide are shown to be effective in protecting isotactic polypropylene (IPP) against thermooxidative degradation. 2[3,5-Di-tert-butyl-4-hydroxyphenyl)-methylene]hydrazine carbothioamide was melt compounded with IPP using a twin screw extruder. The melt flow index of the extruded sample was measured. The extruded granules were injection molded to get specimens suitable for testing mechanical properties, such as heat deflection temperature, Izod impact strength, tensile strength, tensile modulus, flexural strength, and flexural modulus. 2[(3,5-Di-tert-butyl-4-hydroxyphenyl)methylene]hydrazine carbothioamide was found to be an effective melt stabilizer for unstabilized polypropylene. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 129 (1985), S. 43-59 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Alle Arten von Ruß enthalten große Anteile an ungepaarten Elektronen und organischen funktionellen Gruppen. Die Polymerisation wird wahrscheinlich durch die ungepaarten Elektronen auf der Oberfläche ausgelöst; die funktionellen Gruppen haben auf die auslösende Reaktion einen Promotor-Effekt. Alle Eigenschaften wie Textur, Geometrie, Größe der Oberfläche, pH der wäßrigen Aufschlämmung, Aschegehalt und elementare Zusammensetzung haben Einfluß auf die Polymerisation. Diese einschlägigen physikochemischen und Oberflächen-Eigenschaften von nicht modifiziertem und modifiziertem Ruß N 220 wurden im Hinblick auf die Polymerisation von N-Vinylcarbazol untersucht.
    Notes: All grades of carbon black contain large amounts of unpaired electrons and organic functional groups. Polymerization reaction is possibly initiated by the unpaired electrons on the surface; the functional groups have promotional effect on the initiation process. All the properties like texture, geometry, surface area, pH of the aqueous slurry, ash content, and elemental composition have effects on the polymerization reaction. These pertinent physicochemical and surface properties of unmodified and modified N 220 carbon black have been studied in relation to N-vinylcarbazole polymerization.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 134 (1985), S. 151-164 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Initiatorwirksamkeit von unmodifiziertem und durch Vorbehandlung mit verschiedenen protischen und aprotischen Säuren modifiziertem Ruß N 220 wurde für die Polymerisation von N-Vinylcarbazol untersucht. Die physiko-chemischen Eigenschaften der mit diesen Initiatorsystemen erhaltenen Polymeren wurden durch IR-, Röntgen-, 1H-NMR- und 13C-NMR-Spektroskopie, Gelpermeationschromatographie und thermische Analysen untersucht. Unter bestimmten Bedingungen zeigt das entstehende Polymere eine teilweise Unlöslichkeit in Methylethylketon. Im Gegensatz zur üblichen Meinung ist dieses Verhalten nicht auf stereochemische Unterschiede zwischen den Polymereinheiten zurückzuführen, wie durch 13C-NMR-spektroskopische Analysen der in Methylethylketon unlöslichen Fraktion des Polymeren gezeigt wurde.
    Notes: The polymerization initiating activity of carbon black N220, unmodified as well as modified by pretreatment with various protonic and aprotonic acids has been examined in regards to N-vinylcarbazole polymerization. The physico-chemical characteristics of the polymer obtained by these catalyst systems have been investigated by I.R., X-ray, 1H-NMR, 13C-NMR, gel permeation chromatography and thermal analysis measurements. Under certain conditions the resultant polymer shows some partial insolubility in methylethylketone. Contrary to the usual belief, this is not due to any stereochemical difference between the polymeric entities as observed by 13C-NMR spectrum analysis of the methylethylketone insoluble fraction of the polymer.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1980 (1980), S. 447-450 
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 13C-NMR-Spektren von CyclopeptidalkaloidenEs werden die 13C-NMR-Spektren von Zizyphin-A (2), Amphibin-D (3), Amphibin-E (4) und Zizyphin-D (5) studiert und die Ergebnisse im Zusammenhang mit der vorliegenden Konjugation in der Alkoxystyrylamin-Einheit betrachtet.
    Notes: The 13C-NMR spectra of four cyclopeptide alkaloids, namely zizyphine-A (2), amphibine-D (3), amphibine-E (4), and zizyphine-D (5), have been studied. Conclusions have been drawn concerning the conjugation in the alkoxystyrylamine unit present in these compounds.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 11 (1982), S. 2-7 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A simple scheme is described whereby x-ray absorption spectra, including the very strong rapidly varying structure near an absorption edge, may be calculated using only a short program and small amounts of computer time. The analysis also provides general rules for the existence of strong structures at the edge. The scheme can describe any neutral absorbing atom (or, with a little modification, ion) and includes the effect of the core hole when necessary. Fits to experiment show good agreement near absorption edges, with somewhat poorer agreement far from the edge. The method is of use in obtaining absorption spectra for use in crystal spectrometers for x-ray mirror calculations where a knowledge of the fine detail of the absorption is not necessary, but an accurate reproduction of the major structure near the edge is.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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