Summary: The frequency dependence of proton and deuteron NMR relaxation times was determined in selectively deuterated and undeuterated polyisoprene melts and compared to polybutadiene melts. Master curves were generated by the Williams‐Landel‐Ferry (WLF) formalism which resulted in very similar dispersions for all samples with a high and a low frequency branch following characteristic power laws. The results show a consistently weaker frequency dependence than any reported so far for other polymer melts. The reason for this finding is identified in the distribution of intramolecular motion modes, while intermolecular contributions are ruled out. Master curves for 1H relaxation dispersions obtained from measurements between 223 K and 348 K shifted relative to a reference temperature of 296 K. magnified image Master curves for 1H relaxation dispersions obtained from measurements between 223 K and 348 K shifted relative to a reference temperature of 296 K.
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Kariyo et al. (2005) studied this question.
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