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  • 1
    Electronic Resource
    Electronic Resource
    Network formation of polyurethanes due to side reactions (1990)
    s.l. : American Chemical Society
    Macromolecules 23 (1990), S. 1774-1781 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00208a036
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  • 2
    Electronic Resource
    Electronic Resource
    Build-up of polymer networks by initiated polyreactions (1991)
    Springer
    Polymer bulletin 25 (1991), S. 231-237 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The network build-up by polyetherification of a diepoxide released by hydroxyl groups formed in the primary reaction with a diamine was treated by two different methods: i) a rigorous approach in which kinetically generated clusters are statistically combined (cluster approach), and ii) an approximate calculation in which kinetically generated fragments are statistically combined (fragment approach). The cluster approach was used to calculate pregel parameters in part 2 of the series (K.Dušek, Polym.Bull. 13, 321, 1985) and postgel parameters in part 4. of the series (K.Dušek et al., Polym.Bull. 18, 209, 1987). A comparison with the fragment approach for the pregel stage was provided in part 3 of the serie (R.J.J.Williams et al., Polym.Bull. 17, 515, 1987). The same comparison for the postgel stage is now provided. Very close results are found when using both methods for the calculation of the sol fraction and the concentration of elastically active network chains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00310797
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetic Monte-Carlo simulation of network formation (1994)
    Springer
    Polymer bulletin 33 (1994), S. 369-376 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A Monte-Carlo simulation procedure of kinetically controlled structure growth including network formation determined by generalized Smoluchowski equations was described. In addition to intermolecular reactions affected by possible time and space long-range correlations, cyclization or degradation reactions can be considered. The kernel of these reactions can be a function of not only the numbers and types of the reactive groups but also of the composition and structure of the molecule. The random number generator selects a certain reaction event characterized by its rate out of all possible events at four decision levels, (1) reaction mechanism, (2) types of reacting groups, (3) selection of molecule and (4) its reaction partner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314276
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetic Monte-Carlo simulation of network formation (1994)
    Springer
    Polymer bulletin 33 (1994), S. 377-384 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary the simulation described in Part I was applied to random step polyaddition of a trifunctional monomer and the results were compared with exact solution for an infinite system. The gel point conversions, the weight-average degree of polymerization before (P w) and beyond (P w,sol) the gel point, the sol fraction and the cycle rank were used for comparison. The best way for detection of the gel point conversion is the extrapolation of the gel fraction, w g, to w g=0. The largest fluctuations are exhibited by P w and P w,sol. To get results closer to the exact ones, one can repeat several experiments with smaller number of units or increase the number of units, the former way being somewhat more economical. Typical orders of magnitude used were 107 monomeric units.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00314277
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  • 5
    Electronic Resource
    Electronic Resource
    Model reactions of amine curing of glycidylamine epoxy resins: Homopolymerization of N-methylglycidylaniline (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2109-2120 
    Details
    ISSN: 0887-624X
    Keywords: epoxide ; reaction mechanism ; kinetics ; homopolymerization of epoxides ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of homopolymerization of the monofunctional epoxide N-methylglycidylaniline in the presence of a tertiary amine or an amino alcohol has been followed by reversed phase high performance liquid chromatography and size exclusion chromatography. The reaction products were identified by mass spectrometry using potassium ionization of desorbed species (K+IDS). 1,3-Di-N-methylanilino-2-propanol (P) was the main reaction product and low molecular weight oligomers with Mn 〉 600 were also formed. The molecular weight and fraction of oligomers decrease with increasing concentration of the initiator. The suggested complex reaction mechanism involves formation of four stable oligomeric series initiated by reaction of the epoxide with either an OH group of (a) the amino alcohol, (b) product P, (c) traces of water, or (d) the tertiary amine to form ionic species resulting in the ionic propagation. Regeneration of the initiator and formation of new initiating centers during the polymerization are the causes of low molecular weights of oligomers. © 1992 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080301004
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  • 6
    Electronic Resource
    Electronic Resource
    Concise encyclopedia of polymer processing and applications. Edited by Patrick K. Corish, Pergamon, Oxford 1991, 772 pp., hardcover, £ 140, ISBN 0-08-037064-0 (1993)
    Weinheim : Wiley-Blackwell
    Advanced Materials 5 (1993), S. 64-64 
    Details
    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
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19930050118
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of crosslinking on properties of polyurethane elastomers (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 391-398 
    Details
    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: A series of segmented polyurethanes from two polyols, 4,4′-diphenylmethane diisocyanate (MDI) and butane diol was synthesized. The degree of chemical crosslinking was controlled by varying the ratio of poly(oxypropylene) diol to poly(oxypropylene/oxyethylene) triol. The samples were prepared at the stoichiometric ratio of NCO to OH groups and at a constant concentration of hard segments (butane diol; MDI) equal 50 wt %. At low concentrations of the triol the molecular weight of the polyurethanes increases; at higher concentrations (above 9 mol %) crosslinked products are obtained. All samples show a distinct two-phase structure and in the region of 0-150°C the dynamic mechanical behavior is affected by the hard phase. Chemical crosslinking was found to increase the tensile strength and strain at break, but did not affect appreciably the tear strength, hardness, and soft segment glass transition. The stress relaxation rate at room temperature was found to depend both on the elongation and on the degree of crosslinking. A comparison of the sol fractions ws found for crosslinked samples with the predictions of the theory of branching processes proved that the achieved conversions of reactive groups in networks are high (∼ 0.98).
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420211
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  • 8
    Electronic Resource
    Electronic Resource
    Cyclotrimerization of isocyanate groups. I. Catalyzed reactions of phenyl isocyanate (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 52 (1994), S. 895-904 
    Details
    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: Cyclotrimerization of phenyl isocyanate in the presence of various catalysts was studied. All reactions were carried out in 1,4-dioxane at 30-50°C. Reaction products were determined by reverse-phase liquid chromatography. 1,3,5-Triphenyl isocyanurate was formed and also traces of 1,3-diphenylurea and 1,3,5-triphenylbiuret were found. The catalytic activity decreased in the following series: quaternary ammonium salt 〉 organic acid salt ≫ tertiary amine. Apparent rate constants of cyclotrimerization were calculated and the overall reaction order is discussed. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070520708
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  • 9
    Electronic Resource
    Electronic Resource
    Cyclotrimerization of isocyanate groups. II. Catalyzed reactions of phenyl isocyanate in the presence of 1-butanol or butyl-N-phenylurethane (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 53 (1994), S. 1435-1446 
    Details
    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: Cyclotrimerization of phenyl isocyanate at 30-50°C in the presence of 1-butanol or butyl-N-phenylurethane and catalysts of tertiary amine, quaternary ammonium salt, or carboxylate types in 1,4-dioxane was studied by reverse-phase liquid chromatography. Urethane, allophanate, urea, biuret, isocyanurate, and isocyanate model compounds were found in the system. Stability of all reaction products was also examined. The time dependence of evolution of various products depends on the catalyst type and temperature. The overall reaction scheme was proposed. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070531105
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