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  • Artikel  (19)
  • Polymer and Materials Science  (19)
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  • Artikel  (19)
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  • 1
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mats.1992.040010607
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  • 2
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mats.1993.040020606
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  • 3
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: 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.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mats.1993.040020404
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  • 4
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: 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.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1988.070350321
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  • 5
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: 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.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1988.070350619
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  • 6
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: 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.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1988.070360118
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  • 7
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: 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.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1987.070340303
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  • 8
    Digitale Medien
    Digitale Medien
    Additive rules for the 13C NMR shifts of methyl-substituted alkanes and ethylene-propylene copolymersHercules Research Center Contribution Number 1854. (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 135-148 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Detailed 13C NMR chemical shift rules are devised for ethylene and propylene polymers and for low-molecular-weight analogs. The rules are additive and account for substituent effects as well as for configurational sequences. The agreement between the observed and the predicted shifts is excellent. A computer program has been written to obtain the predicted shifts quickly and with minimum effort.
    Zusätzliches Material: 7 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1987.021880112
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  • 9
    Digitale Medien
    Digitale Medien
    Spectral simulation and characterization of polymers from ethene and propene by 13C NMRHercules Research Center Contribution Number 1819. (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 2665-2677 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A general treatment is devised for the 13C NMR spectral analysis of copolymers involving ethene and propene. The basis of the method is the computerized “synthetic approach” proposed earlier (Anal. Chem.) 56, 2320 (1984) and entails the use of first-order Markovian statistics, Monte Carlo polymer chain generation, spectral prediction, and spectral simulation. By this means, copolymer and homopolymer spectra of increasing complexity are readily simulated. The method is shown to accommodate all structural types (viz. stereosequences, regiosequences, and polymer chain ends) and provides good results for atactic poly(propylene), irregular poly(propylene), isotactic ethene/propene copolymers, ethene/propene rubbers, and ethene/propene oils.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1987.021881117
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  • 10
    Digitale Medien
    Digitale Medien
    13C NMR characterization of ethylene oxide/epichlorohydrin copolymer (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 267-276 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The 13C NMR spectra of ethylene oxide/epichlorohydrin copolymers are fully assigned. Information available includes copolymer composition, comonomer sequence distribution, and epichlorohydrin tacticity. The comonomer sequence distribution can be fitted to a two-component (Bernoullian/Bernoullian) statistical model.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1991.021920208
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