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  • 1
    Electronic Resource
    Electronic Resource
    The free-radical terpolymerisation of ethylene, methyl acrylate and vinyl acetate at high pressure. Polymerization testsCf.13. (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 211 (1993), S. 131-140 
    Details
    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
    URL: http://dx.doi.org/10.1002/apmc.1993.052110112
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  • 2
    Electronic Resource
    Electronic Resource
    Radical terpolymerization of ethylene, methyl acrylate and vinyl acetate under high pressure. Physical properties of the polymers (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 207 (1993), S. 145-155 
    Details
    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
    URL: http://dx.doi.org/10.1002/apmc.1993.052070114
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  • 3
    Electronic Resource
    Electronic Resource
    Michael Adducts of (Alkynylcarbene)pentacarbonylchromium Complexes: Formation, Stereochemistry, and Thermal Rearrangement (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2051-2065 
    Details
    ISSN: 0009-2940
    Keywords: Chromium, alkynylcarbene complexes ; Vinylcarbenechromium complexes, β-donor-substituted ; Carbene complexes, vinyl, chelated ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: β-Donor-substituted α,β-unsaturated chromium carbene complexes (CO)5CrC(OEt)C = CR(XR′n) (X = N, O, S; 3, 9, 11-16, 22-25) have been synthesized by Michael addition of amines, alcohols, and thiols to alkynylcarbene complexes (CO)5CrC-(OEt)C≡CR (1). The configurations of the newly formed C-C double bonds have been determined by NOE/NOESY measurements and X-ray crystal structure analysis. These vinylcarbene complexes lose one carbonyl ligand in refluxing tetrahydrofuran to give tetracarbonyl complexes (CO)4CrC(OEt)C = CR(XR′n) (X = N, O, S; 26-28).
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250913
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  • 4
    Electronic Resource
    Electronic Resource
    Coordinated 1-Aza-1,3-butadienes: Stable Intermediates in the Formation of Pyridines from [(β-Aminoethenyl)carbene]chromium Complexes (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 2535-2541 
    Details
    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
    URL: http://dx.doi.org/10.1002/cber.19931261131
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  • 5
    Electronic Resource
    Electronic Resource
    Michael Addition of Imines to Alkynylcarbene Complexes with Subsequent Intramolecular Cyclization - An Efficient Three-Step Synthesis of 2H-Pyrroles (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 911-920 
    Details
    ISSN: 0009-2940
    Keywords: Chromium, [2-(methyleneamino)ethenyl]carbene complexes ; Michael addition of imines ; (1-alkynylcarbene)-chromium complexes ; 2H-Pyrroles ; Cyclization of {[2-(methyleneamino)ethenyl]carbene}chromium complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Imines 7, 11-13 were added to (1-alkynylcarbene)chromium complexes 6a-d to form {[2-(methyleneamino)ethenyl]-carbene}chromium complexes 8a-d, 14a-d, 15a-d, 16a-d in good to very good yields (63-98%) except for two cases (41-59%). The carbene ligands of the latter compounds cyclize to 2H-pyrroles 9a-d, 17a-d, 18a-d, 19a-d upon heating in tetrahydrofuran solution to 50-55°C.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270520
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  • 6
    Electronic Resource
    Electronic Resource
    Eni naturwissenschaftliches Literaturkarussell. Geowissenschaften (1993)
    Weinheim : Wiley-Blackwell
    Chemie in unserer Zeit 27 (1993), S. XIII 
    Details
    ISSN: 0009-2851
    Keywords: Chemistry ; Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ciuz.19930270212
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  • 7
    Electronic Resource
    Electronic Resource
    Photoreactive cellulose derivatives with comb-like structure, 1. Modification of O-trialkylsilylcellulose with cinnamic acid-containing side chains (1990)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 191 (1990), S. 2985-2991 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Trimethyl- and tert-butyldimethylsilylcellulose were esterified with cinnamic acid, 4-nitrocinnamic acid, 4-(hexyloxy)cinnamic acid, 4-(hexadecyloxy)cinnamic acid and N-cinnamoyl-11-aminoundecanoic acid yielding photosensitive comb-like cellulose derivatives. The UV-irradiation of solid films of tert-butyldimethylsilylcellulose cinnamate, trimethylsilylcellulose 4-nitrocinnamate and tert-butyldimethylsilylcellulose-4-hexyloxycinnamate were performed and the decrease of the absorption maxima was correlated with E/Z isomerisation and [2 + 2]-cycloaddition. A possible application of the described photoreactive cellulose esters in the area of membrane technology is discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1990.021911215
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and properties of monodisperse polydimethylsiloxane networks (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 2697-2710 
    Details
    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
    URL: http://dx.doi.org/10.1002/pola.1993.080311105
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  • 9
    Electronic Resource
    Electronic Resource
    Shear thickening (dilatancy) in concentrated dispersions (1990)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 36 (1990), S. 321-332 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new criterion is introduced for the onset of shear thickening in a concentrated dispersion. The criterion follows from the assumption that shear thickening occurs when the shear forces overrule the interparticle forces. A force balance at small interparticle distances is used to predict the dependence of this critical shear rate on the volume fraction. It is deduced that the critical shear rate is proportional to the interparticle distance, has a linear dependence on the magnitude of the stabilizing force, an inverse linear dependence on the dispersion medium viscosity, and an inverse linear dependence on the particle radius. The model is confirmed experimentally with viscosity measurements on various electrostatically stabilized dispersions. The validity of the model is also checked with data obtained from the literature. Experiments indicate that polydisperse dispersions exhibit pronounced shear thickening but with a less dramatic increase in viscosity than monodisperse dispersions.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690360302
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  • 10
    Electronic Resource
    Electronic Resource
    Separation of N-arylthiazoline-2-(thi)-one atropisomers on p-methylbenzoyl cellulose beads: A factorial design approach (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 207-212 
    Details
    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
    URL: http://dx.doi.org/10.1002/chir.530050403
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