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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 211 (1993), S. 131-140 
    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: In dieser Arbeit wurde die Terpolymerisation unter Hochdruck am Beispiel des Systems Ethylen-Methylacrylate-Vinylacetat untersucht. Die Polymerisationsversuche wurden in einer kontinuierlich betriebenen Hochdruckpolymerisationsanlage durchgeführt. Zur Beurteilung der Druck- und Temperatureinflüsse auf die Reaktion wurde die Polymerisation bei zwei verschiedenen Drücken von 1900 und 1100 bar sowie Temperaturen von 180 und 230°C durchgeführt. Durch Variation der Konzentrationen der Monomeren Ethylen, Methylacrylat und Vinylacetat im Ansatz wurden Polymerisate mit unterschiedlicher Zusammensetzung erhalten. Das Konzentrationsverhältnis der Monomeren im Reaktor wurde aus der Auswaage und dem Comonomergehalt des Polymerisats sowie der Feedzusammensetzung unter Anwendung der Massenbilanz für den idealen Rührkessel berechnet. Daraus wurden die Copolymerisationsparameter der drei möglichen binären Copolymerisationen Ethylen/Methylacrylat, Ethylen/ Vinylacetat und Methylacrylat/Vinylacetat Bestimmt. Mit diesen Daten kann die Zusammensetzung eines Produkts aus der kontinuierlichen Polymerisation in einem Rührautoklaven vorausberechnet werden.
    Notes: In this study, the terpolymerisation, under high pressure, has been examined for the ethylene-methyl acrylate-vinyl acetate system. The polymerisations were carried out in a high pressure polymerisation facility designed for continuous operation. To assess the effect of pressure and temperature on the reaction, polymerisation was carried out at two different pressures of 1 900 and 1 100 bar and at temperatures of 180 and 230°C. By varying the concentration of the ethylene, methyl acrylate and vinyl acetate monomers in the feed, polymers of different composition were obtained. The ratio of the monomer concentrations in the reactor was calculated from the amount of polymer weighed out and its comonomer content as well as the composition of the feed, using the mass balance for the ideal stirred tank reactor. The result was used to determine the reactivity ratios of the three possible binary copolymerisation systems ethylene/methyl acrylate, ethylene/vinyl acetate and methyl acrylate/ vinyl acetate. This made it possible to predetermine, by calculation, the composition of a product obtained by continuous polymerisation in a stirred autoclave.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 207 (1993), S. 145-155 
    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: Um den Einflulß der Reaktionsbedingungen Druck und Temperatur sowie der Comonomeren Acrylsäuremethylester und Vinylacetat auf das entstandene Ethylen-Acrylsäuremethylester-Vinylacetat-Terpolymerisat aufzuzeigen, wurden Polymerisationsversuche in einem kontinuierlich betriebenen Rührautoklaven durchgeführt. Der Druck wurde zwischen 1 100 und 1900 bar variiert. Die Temperatur lag bei 180 bzw. 230°C. Die mittlere Verweilzeit betrug 40 Sekunden. Als Initiator wurden t-Butylperpivalat und t-Butylperethylhexanoat in Konzentrationen von 50 bis 180 mol-ppm im Ethylenzulauf gewählt. Die erhaltenen Polymeren wurden durch Bestimmung ihrer Zusammensetzung, ihrer Dichte, der Kristallinität, des Schmelzpunktes, der Glasßbergangstemperatur, des Schmelzindexes, des mittleren Molekulargewichtes sowie der Zugfestigkeit und Reindehnung charakterisiert.
    Notes: Polymerization tests were carried out in a stirred autoclave designed for continuous operation in order to determine the influence of the reaction pressure and temperature and of the acrylic acid methyl ester and vinyl acetate comonomers on the ethylene-acrylic acid methyl ester-vinyl acetate terpolymer formed. Pressures between 1100 and 1900 bar and temperatures of 180 and 230°C were used. The average residence time was 40 seconds. Tertiary butyl perpivalate and tertiary butyl perethyl hexanoate in concentrations of 50 to 180 mol-ppm in the ethylene feed were used as initiators. The characteristic properties of the polymers obtained were assessed by determining their composition, density, crystallinity, melting point, glass transition temperature, melt index, the average molecular weight, tensile strength and elongation at break.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0009-2940
    Keywords: Chromium, (β-aminoethenyl)carbene complexes ; 1-Aza-1,3-butadienes, coordinated ; Pyridines, cycloaddition with alkynes ; Chelated chromium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [(β-Aminoethenyl)carbene]chromium complexes 3a-c rearrange to coordinated 1-aza-1,3-butadienes 6a-c, which undergo cycloadditions with alkynes 7a, c to pyridines 9a, 10a-c.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 27 (1993), S. XIII 
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    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 A: Polymer Chemistry 31 (1993), S. 2697-2710 
    ISSN: 0887-624X
    Keywords: monodisperese ; hydrosilylation ; network structure ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: α,ω-Divinyl-terminated polydimethylsiloxane polymers with low polydispersivity were synthesized via anionic polymerization of hexamethylcyclotrisiloxane (D3). Five “monodisperse” polymers with different molecular weights were hydrosilylated with tetrakisdimethylsiloxysilane in the presence of platinum catalysts and inhibitors to form crosslinked networks. Control studies to determine the effect of platinum, silicon hydride, and heat were performed to verify that no redistribution occurred during hydrosilylation. The properties of these cured samples were characterized chemically by degradation with trifluoromethanesulfonic acid in the presence of hexamethyldisiloxane, infrared spectroscopy, and nuclear magnetic spectroscopy. Mechanical properties were studied by measurements of Shore A hardness, dynamic shear modulus, and tensile modulus. The relationship between the molecular weight of the vinyl polymer and the final properties of the cured networks was measured. © 1993 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0899-0042
    Keywords: chiral HPLC ; solvent effect ; quantitative substituent effects ; molecular recognition mechanism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A two level full factorial design has been applied to quantify the effect of three selected structural parameters on the capacity factors and chiral separation of atropisomers in N-arylthiazoline-2-(thi)-ones derivatives on tris(p-methylbenzoyl) cellulose beads. The behavior of the two enantiomers is influenced by different factors which might result from different retention sites within the same stationary phase. It appears that the two enantiomers behave independently on the CSP, the order of elution and separation being controlled by a minor steric modification in a very precise location in the molecule for one enantiomer. The methodology of the experimental design allows the comparison of equations generated from data issued from designed compounds. These equations afford much more information than the step by step comparison of individual molecules. In our case, the tris(p-methylbenzoyl)cellulose beads and microcrystalline cellulose triacetate appear as complementary CSPs for the resolution of atropisomers of the series studied. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0935-9648
    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
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 319-326 
    ISSN: 0887-6266
    Keywords: thermal expansion ; thin films ; ellipsometer ; glass transition ; refractive index ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The glass transition (Tg) of thin polystyrene films (ca. 3000 A˚) cast on silicon wafers was determined by a new technique. An ellipsometer was used to determine the refractive index and thickness of the polystyrene films. Tg was determined by measuring the temperature dependence of the refractive index. The change in thickness with temperature was used to calculate the linear and bulk thermal expansion coefficients of the material. A significant shift in Tg, possibly due to strains induced in the cooled films, was observed between heating and cooling for polystyrene films. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 667-675 
    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: The curing of silicone lattices has been studied using 29Si NMR spectroscopy. It has been found that cross-linking occurs prior to removal of the water. Stabilizers prevent gelation by slowing down the rate of condensation, particularly of higher functionality cross-linkers. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 2003-2010 
    ISSN: 0887-6266
    Keywords: light scattering ; liquid crystals ; polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It is 50 years since Debye first described the use of light scattering for the characterization of polymer solution. Ben Chu has been a leader in its subsequent development. Significant advances in theory, experimental techniques, their interpretation, and application during this period are described. © 1993 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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