Authors
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Wiesner, B. ; Kohn, B. ; Mende, M. ; Scheler, U.
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Title
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Polymer chain mobility under shear - a rheo-NMR investigation
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Date
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21.12.2018
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Number
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55919
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Abstract
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The local dynamics in polymer melts and the impact of external shear in a Couette geometry have been investigated using rheological nuclear magnetic resonance (NMR). The spin-spin relaxation time, T2, which is sensitive to chain-segment motion, has been measured as a function of shear rate for two samples of poly(dimethylsiloxane). For the low-molecular-weight sample, a mono-exponential decay is observed, which becomes slightly faster with shear, indicating restrictions of the polymer chain motion. For the high-weight sample, a much faster bi-exponential decay is observed, indicative of entanglements. Both components in this decay become longer with shear. This implies that the free polymer segments between entanglements become effectively longer as a result of shear.
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Publisher
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Polymers
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Wikidata
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Citation
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Polymers 10 (2018) ID1231
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DOI
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https://doi.org/10.3390/polym10111231
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Tags
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polymer mobility rheo nmr entanglements
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