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  • 1
    Electronic Resource
    Electronic Resource
    Multicomponent analysis of poly(propylene) using fractionation, tacticity and molecular weight dataHercules Research Center Contribution Number 2119. (1992)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Theory and Simulations 1 (1992), S. 415-427 
    Details
    ISSN: 1018-5054
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Heterogeneous Ziegler-Natta catalysts are known to contain multiple catalytic sites and produce polymers that contain multiple components. An approach is described in this work that combines fractionation, 13C NMR and molecular weight distribution data to determine the number and the characteristics of the different components found in the polymer. The methodology is applied to published data on poly(propylene). The analyses indicate that poly(propylene) made with heterogeneous Ziegler-Natta catalysts consists of at least four components. Three of these components obey enantiomorphic-site models, and the fourth component obeys Bernoullian model.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mats.1992.040010607
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  • 2
    Electronic Resource
    Electronic Resource
    NMR studies of the effects of isolated variables on polyolefin microstructure and Ziegler-Natta catalytic sitesHercules Research Center Contribution Number 2194. (1993)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Theory and Simulations 2 (1993), S. 901-916 
    Details
    ISSN: 1018-5054
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyolefins made with heterogeneous Ziegler-Natta catalysts contain multiple components as a result of the different catalytic sites present in the catalyst. If a series of similar catalysts are made where only one experimental variable is varied, then a family of similar polymers can be prepared where the polymer microstructure (as studied by NMR) reflects the effects of that variable. An analytical methodology is developed in this work that permits a systematic analysis to be carried out on the NMR data of such polymers. Thus, from the NMR spectra one can deduce the influence of an isolated variable on the polymer components and (indirectly) on the catalytic sites. Illustrated in this work are the effects of Lewis bases on the catalytic sites, catalyst pretreatment with a higher olefin, and catalyst grinding. The approach can be applied to study both homopolymer tacticity and copolymer sequences.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mats.1993.040020606
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  • 3
    Electronic Resource
    Electronic Resource
    Perturbed enantiomorphic-site modelHercules Research Center Contribution Number 2169. (1993)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Theory and Simulations 2 (1993), S. 561-576 
    Details
    ISSN: 1018-5054
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The perturbed enantiomorphic-site (E) model was developed for the analysis of tacticity of Ziegler-Natta polymers. Theoretical probability expressions for tacticity diads, triads, tetrads and pentads were derived, and a computer program incorporating perturbed enantiomorphic-site and Bernoullian models was written to facilitate NMR analysis. Examples are shown of the use of the perturbed models to study the 13C NMR tacticity of poly(propylene) made with homogeneous metallocene catalysts. The perturbed E model is shown to be a suitable theoretical framework for the analysis of many polymers made with these catalysts.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mats.1993.040020404
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  • 4
    Electronic Resource
    Electronic Resource
    13C-NMR characterization of poly(1,5-hexadiene)Hercules Research Center Contribution Number 1946. (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 35 (1988), S. 825-829 
    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: Poly(1,5-hexadiene) was prepared and its structure characterized by high-field 13C nuclear magnetic resonance. The polymer was shown to contain repeating five-membered rings separated by methylene bridges, with both cis and trans placements present in a 54 : 46 ratio. The result is compatible with the Marvel-Garrison two-step reaction mechanism.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070350321
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  • 5
    Electronic Resource
    Electronic Resource
    13C-NMR sequence determination for multicomponent polymer mixturesHercules Research Center Contribution Number 1953. (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 35 (1988), S. 1639-1650 
    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 general treatment is developed for the 13C-NMR analysis of polymers which contain several components. Reaction probability models and computer optimization techniques are used to resolve the NMR spectral data into separate components. The use of generalized multistate statistical models is introduced and is found to be very suitable for such systems. The computations are simplified by means of computer programs. The need for, and the relevance of, this approach are illustrated by the tacticity problems in polybutylene and polypropylene where two-state and three-state models are used, and copolymer triad sequence analysis for several olefin and acrylic copolymers where two-state models are needed. Three copolymer examples are given: propylene/butylene, ethylene/propylene, and acrylamide/acrylate.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070350619
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  • 6
    Electronic Resource
    Electronic Resource
    Stereochemistry of vinyl polymers and NMR characterizationHercules Research Center Contribution No. 1936. (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 36 (1988), S. 229-241 
    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: The configuration of vinyl polymers has been conventionally described by either Bovey's or Price's formalism. In this work, the relationships between these two formalisms are derived, and their relevance to polymerization mechanisms is delineated. Experimental data for nuclear magnetic resonance (NMR) pertaining to either chain-end control or catalytic-site control are tested using the computerized “analytical approach.” Suitable polymeric systems are illustrated.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1988.070360118
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  • 7
    Electronic Resource
    Electronic Resource
    Free-radical polymerization of methyl methacrylate initiated by thiol alone (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 579-582 
    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: Three different alkyl thiols, i.e., n-propylthiol, isopropylthiol, and 2-methyl-2-undecanethio1, were proved efficient to initiate the polymerization of methyl methacrylate at 40°C. The initial polymerization rate, Rp, increases with increasing thiol concentration but cannot be described by a single-power law. However, Rp is proportional to 1.3th power of the monomer concentration, indicating the participation of monomer in the initiation reaction. With increase of the polarity of solvents, Rp decreases, demonstrating the polar property of the initiating intermediate. The apparent activation energy of overall polymerization was calculated to be 9.3 kcal/mol. Molecular weight measurements indicated the twofold function of the thiol as both an initiator and a regulator.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070450403
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  • 8
    Electronic Resource
    Electronic Resource
    Bi-ionic potentials in anion exchange membranes (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 851-853 
    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
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210326
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  • 9
    Electronic Resource
    Electronic Resource
    13C-NMR determination of the tacticity of polyepichlorohydrinHercules Research Center Contribution Number 1934. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 34 (1987), S. 909-912 
    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: The microstructure of polyepichlorohydrin was directly studied by high-field 13C-NMR. Spectral features were found that correspond to different tacticities. By using curve deconvolution techniques, the different tacticities were assigned and quantified.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070340303
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  • 10
    Electronic Resource
    Electronic Resource
    Time lag and permeation rate in liquid/liquid dialysis (1975)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 19 (1975), S. 3087-3091 
    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: Time lag and permeation rate in liquid/liquid dialysis in general are found different from those in pervaporation. Theoretical treatments of time lag in liquid/liquid dialysis indicate that time lag, in certain cases, may be correlated to the “relaxation time” of the membrane, defined as the time required for the membrane to relax, or as the change of the permeation flux of diffusable species from initial flux to steady state due to the long time required for the dialysis solvent to reach steady state in the membrane. The permeation of dichlorobenzene in a Teflon-FEP membrane for both the operations of liquid/liquid dialysis and pervaporation was measured as an example. It was found that the time lag in liquid/liquid dialysis is much longer than that calculated from a diffusion constant calculated from pervaporation. Permeation rate and activation energy are also different in both operations.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1975.070191113
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