Abstract
AbstractA theoretical treatment of the nonexponential relaxation behavior of the different proton nuclear magnetic resonance (NMR) relaxation processes in polymer melts is presented. Formulas are derived for a three‐component model given by two versions and a homogeneous distribution of correlation times. The theoretical results were tested with measurements of T1, T2e, and T2 as functions of frequency and molecular mass in linear fractionated polyethylene samples. While the T1 relaxation always yields exponential magnetization decays, the T2e and T2 measurements show biexponential relaxation behavior. From the calculations it was found that the correlation time of the local motion is independent of the molecular mass, whereas the correlation time of the slowest motional process increases with M2.8w for the three‐component model and with M2.2w for the distribution of correlation times, respectively. © 1992 John Wiley & Sons, Inc.
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