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@ARTICLE{Hofmann:825917,
      author       = {Hofmann, M. and Kresse, B. and Heymann, L. and Privalov, A.
                      F. and Willner, L. and Fatkullin, N. and Aksel, N. and
                      Fujara, F. and Rössler, E. A.},
      title        = {{D}ynamics of a {P}aradigmatic {L}inear {P}olymer: {A}
                      {P}roton {F}ield-{C}ycling {NMR} {R}elaxometry {S}tudy on
                      {P}oly(ethylene–propylene)},
      journal      = {Macromolecules},
      volume       = {49},
      number       = {22},
      issn         = {1520-5835},
      address      = {Washington, DC},
      publisher    = {Soc.},
      reportid     = {FZJ-2017-00196},
      pages        = {8622 - 8632},
      year         = {2016},
      abstract     = {The dynamics of melts of linear
                      poly(ethylene-alt-propylene) (PEP) of different molar masses
                      (M) is investigated by 1H field-cycling (FC) NMR
                      relaxometry. Employing a commercial and a home-built
                      relaxometer the spin-lattice relaxation rate R1(ω) is
                      measured in the frequency range of 200 Hz to 30 MHz and the
                      temperature range of 200–400 K. Transforming the FC NMR
                      relaxation data to the susceptibility representation and
                      applying frequency–temperature superposition, master
                      curves for the dipolar correlation function CDD(t/τα)
                      (containing intra- and intermolecular contributions) are
                      constructed which extend up to six decades in amplitude and
                      eight in time. Here, τα is the time scale of the
                      structural (α-) relaxation, which is obtained over several
                      decades. Comparison with previously reported FC data for
                      polybutadiene (PB) discloses very similar CDD(t). Depending
                      on M, all the five relaxation regimes of a polymer melt are
                      covered: in addition to the α-process (0) and the terminal
                      relaxation (IV), which are immanent to all liquids, three
                      polymer-specific power-law regimes (Rouse, I; constraint
                      Rouse, II; and reptation, III) are found, i.e. CDD(t) ∝
                      t–ε. The corresponding exponents (εI–III) are close to
                      those predicted by the tube-reptation (TR) model for the
                      segmental translation. In contrast to previous
                      interpretation the intermolecular relaxation dominates
                      CDD(t), in particular in regime II and beyond. The
                      decomposition into intra- (mediated by segmental
                      reorientation) and intermolecular relaxation (mediated by
                      segmental translation) via isotope dilution experiments
                      yields Cinter(t) = Ctrans(t) ∝ t-0.28±0.05 concerning PEP
                      and Cinter(t) ∝ t-0.30±0.05 concerning PB for regime II
                      (high-M limit). For the reorientational correlation function
                      Cintra(t) = C2(t) ∝ t–0.50±0.05 (PEP) and C2(t) ∝
                      t–0.45±0.05 (PB) are obtained. These exponents εIIintra
                      are at variance with εIITR = 0.25 predicted by the TR
                      model. The fact that translation conforms to the TR model,
                      while reorientation does not, now confirmed for the two
                      polymers PEP and PB, challenges de Gennes’
                      return-to-origin hypothesis which assumes strong
                      translational-rotational coupling in the TR model.},
      cin          = {ICS-1 / Neutronenstreuung ; JCNS-1},
      ddc          = {540},
      cid          = {I:(DE-Juel1)ICS-1-20110106 / I:(DE-Juel1)JCNS-1-20110106},
      pnm          = {551 - Functional Macromolecules and Complexes (POF3-551) /
                      6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623)
                      / 6215 - Soft Matter, Health and Life Sciences (POF3-621)},
      pid          = {G:(DE-HGF)POF3-551 / G:(DE-HGF)POF3-6G4 /
                      G:(DE-HGF)POF3-6215},
      typ          = {PUB:(DE-HGF)16},
      UT           = {WOS:000388913500025},
      doi          = {10.1021/acs.macromol.6b01906},
      url          = {https://juser.fz-juelich.de/record/825917},
}