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  • 1
    Electronic Resource
    Electronic Resource
    Molecular order and density of skin and core in drawn polypropylene investigated by spectroscopic carbon-13 NMR imaging (1992)
    s.l. : American Chemical Society
    Macromolecules 25 (1992), S. 3315-3316 
    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/ma00038a049
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  • 2
    Electronic Resource
    Electronic Resource
    Aging and phase separation of elastomers investigated by NMR imaging (1991)
    s.l. : American Chemical Society
    Macromolecules 24 (1991), S. 2183-2188 
    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/ma00009a007
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of tensile stress on the phenylene flips in polycarbonate studied by two-dimensional solid-state NMR (1992)
    s.l. : American Chemical Society
    Macromolecules 25 (1992), S. 5542-5544 
    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/ma00046a068
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  • 4
    Electronic Resource
    Electronic Resource
    Two-dimensional interferometry (1987)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 58 (1987), S. 911-919 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A two-dimensional cross-correlation technique is described, which allows time-resolved pump-and-probe experiments to be performed with two continuous broadband excitations. The progress of a rate process stimulated by one excitation is investigated by the second. Within the linear response limit the technique is characterized by low excitation power and high response energy. Potential applications are in the study of dynamic mechanical and electrical material properties by spectroscopic methods such as nuclear-magnetic resonance or Fourier transform infrared spectroscopy, and in optical T1 measurements with a time resolution on the order of the inverse bandwidths of the excitations. A two-dimensional digital interferometer capable of microsecond resolution is described and used to illustrate the principle of the method with an investigation of a two-input electronic circuit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139575
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  • 5
    Electronic Resource
    Electronic Resource
    Investigation of systematic noise in stochastic linear system analysis (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1140-1144 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In stochastic system analysis, transfer functions are retrieved from experimental data by cross correlation. A well-known linear cross correlator is the Michelson interferometer used in Fourier transform infrared spectroscopy. Due to the noise excitation, the transfer functions are inherently contaminated by systematic noise. It is shown, that in the limit of observation periods which are long compared to the maximum time shift in the cross correlation, the systematic noise decreases in proportion to the inverse square root of the data-acquisition time. Experimental data from stochastic NMR spectroscopy illustrate that the resolution of the transfer function can be optimized independent of the observation period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138671
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  • 6
    Electronic Resource
    Electronic Resource
    Residual dipolar couplings by 1H dipolar-encoded longitudinal magnetization, double- and triple-quantum nuclear magnetic resonance in cross-linked elastomers (1999)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 111 (1999), S. 402-415 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The measurements of residual dipolar couplings in elastomer system is desirable, because they reflect the hindrance to molecular motions by the cross-linking, topological constraints and the external factors like mechanical stress. Dipolar-encoded longitudinal magnetization nuclear magnetic resonance (NMR) decay curves, double-quantum and triple-quantum NMR buildup intensities for measuring the residual dipolar couplings, and the associated dynamic order parameters are introduced. It is shown that in the short excitation time regime the effective dipolar network is simplified. In the limit of this model based on localized dipolar couplings, the spin response to two-dimensional pulse sequences used to record multiple-quantum (MQ) NMR coherences was evaluated for longitudinal magnetization, double-, and triple-quantum coherences of methylene, and methyl protons in synthetic 1,4-cis-polyisoprene. The dynamic order parameters can be evaluated from this NMR response using a classical scale-invariant polymer model. These dynamic order parameters were measured for a cross-link series of synthetic polyisoprene and correlated with the cross-link density. The decay rates of the Hahn-echo amplitudes reflecting residual dipolar couplings as well as effects of molecular motion are also measured for the same cross-link series. The contribution of molecular motions to the transverse relaxation can be separated from the residual dipolar couplings using a train of magic echoes. The sensitivity of these transverse relaxation rates to the cross-link density is compared to that of residual dipolar couplings. The NMR time scale is shorter for the dipolar-encoded longitudinal magnetization and MQ experiments as compared to transverse relaxation experiments leading to an increased sensitivity to cross-link density of the former approaches. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.479291
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  • 7
    Electronic Resource
    Electronic Resource
    In situ investigation of SBR vulcanization: A combined study of1H-NMR and vulcametry (1996)
    Springer
    Colloid & polymer science 274 (1996), S. 191-196 
    Details
    ISSN: 1435-1536
    Keywords: Vulcanization ; NMR ; NMR imaging ; vulcametry ; simulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract For the first time, in situ NMR measurements were performed during sulfur vulcanization of unfilled SBR. A vulcanization device was constructed for use in combination with a standard microimaging probe in a vertical bore NMR magnet.1H-linewidth measurements are correlated with cure simulations in a vulcameter to explain the increase of the linewidth during the vulcanization. Inhomogeneous heating conditions in the sample result in an inhomogeneous course of the vulcanization as a function of time. The spatial dependence of this process was monitored by NMR imaging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00665635
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  • 8
    Electronic Resource
    Electronic Resource
    Investigation of stress distributions in filled polysiloxane by NMR imaging (1993)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 44 (1993), S. 125-131 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: NMR imaging is applied to industrial poly(dimethylsiloxane). Samples were investigated in the strained and unstrained state with and without a cut, and compared with two model compounds. Inhomogeneous filler distributions cause variations in the magnetic susceptibility and lead to contrast in gradient-echo images. T2-parameter images revealed distributions in segmental mobility associated with the filler inhomogeneities as well as with the cut. The images were recalibrated to give strain and stress images by use of integral stress and T2 values determined for macroscopic uniaxial strain. The effects of filler inhomogeneities appear larger in the NMR images than in polarization micrographs because of magnification by magnetic field distortions from susceptibility differences in gradient-echo images, and because changes in segmental mobility of surrounding polymer chains are detected rather than the filler itself. The methods can also be applied to 3D imaging of nontransparent rubbers.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1993.010440302
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  • 9
    Electronic Resource
    Electronic Resource
    Solid state NMR investigation of cationic polymerized epoxy resins (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 289-295 
    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: Cationic UV-polymerized resins, based on cycloaliphatic epoxides with aryl sulfonium salts as photoinitiators and polypropylene glycols of variable length as flexibilizers, have been investigated with respect to the network-forming reactions and the morphology of the resulting polymers. The combination of UV-curing and thermal postcure makes the chemical process complex and dependent on many variables, such as photoinitiator, exposure time, reaction temperature, and polyol components. Structure and curing of the epoxide were investigated by 13C CPMAS NMR. Morphology and domain sizes were studied by spin diffusion experiments using the novel “dipolar filter” technique for selective magnetization of mobile components.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070440213
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