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  • American Institute of Physics (AIP)  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Use of carbon–carbon nuclear spin diffusion for the study of the miscibility of polymer blends (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 1585-1598 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: This high-resolution solid-state NMR work explores the usefulness of carbon–carbon nuclear spin diffusion to probe the miscibility of polymer blends. Experiments involving one- and two-dimensional NMR spectra, applied to blends of poly(ethylene terephthalate) (PET) and bisphenol-A polycarbonate (BPAPC), show that spin exchange occurs between carbon-13 nuclei located in monomer units that belong to the two different homopolymers. Carbon spin diffusion, which strongly depends on the internuclear distance, is explored as a possible probe for specific interactions between polar groups of the two polymers. Our results clearly show that the PET/BPAPC blends studied are homogeneously mixed at distances of 4.5 to 6 A(ring).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.448434
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  • 2
    Electronic Resource
    Electronic Resource
    Dynamics of the 13C spin-exchange process in solids: A theoretical and experimental study (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 7077-7086 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Spin exchange between rare nuclei such as 13C occurs readily when the rare nuclei are coupled to a reservoir of abundant spins such as 1H, but the mechanism by which the abundant spins enable the exchange process has not fully been clarified. Two different equations to describe the rate of spin exchange in terms of the magnitude of the dipolar coupling between the carbons and the nature of the carbon–proton interaction have been proposed. The derivation of one of the equations with the projection-operator formalism is described in this paper; the derivation of the other is outlined. Neither equation fully explains the results from a single crystal of glycine, 90% enriched at the carbonyl position. The discrepancies appear to result from the assumptions used in the derivations. Good agreement with experimental results can be obtained with an equation expressed in terms of the degree of overlap of the signals from each type of carbon in the normal nuclear magnetic resonance (NMR) spectrum if allowance is made for the fact that the surrounding protons affect the environments of both carbons in a pair undergoing spin exchange in a similar manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451394
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    Paper (German National Licenses)
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