The deuteron NMR Hahn echo decay in polyethylene oxide melts

The deuteron transverse relaxation properties of polyethylene oxide melts four different molecular weights, covering the range from onset entanglements to regime fully entangled chains, are investigated using Hahn echo decays over an extensive time interval up ten times effective spin time. results compared predictions based on Rouse and reptation formalisms, taking into account dynamical heterogeneity linear polymer chains produced by end segments. experimental can be described qualitatively a combination both models, with contribution dynamics increasing growing chain length. transition is continuous, rather than being characterized sharp boundaries. Up weight 300.000 g/mol, predicted limit pure not yet reached. Quantitative deviations as computed numerical procedures become observable toward long-time discussed in terms shortcomings available theories.