This title appears in the Scientific Report : 2003 

Direct observation of the transition from free to constrained single-segment motion in entangled polymer melts
Wischnewski, A.
Monkenbusch, M. / Willner, L. / Richter, D. / Kali, G.
Neutronenstreuung; IFF-NST
Physical review letters, 90 (2003) S. 058302
College Park, Md. APS 2003
058302
10.1103/PhysRevLett.90.058302
Journal Article
Kondensierte Materie
Physical Review Letters 90
J
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Please use the identifier: http://dx.doi.org/10.1103/PhysRevLett.90.058302 in citations.
Please use the identifier: http://hdl.handle.net/2128/1280 in citations.
We report a direct determination of the time dependent mean-squared segment displacement of a polymer chain in the melt covering the transition from free to constraint Rouse relaxation along the virtual tube of the reptation model. This has been achieved by a neutron spin-echo (NSE) measurement of the segmental self-correlation function as conveyed by the spin-incoherent scattering from two fully protonated polymer melts, polyethylene and polyethylene propylene. Within the scenario of de Gennes reptation model a transition of the time dependence of segmental mean-squared displacements from proportional tot(1/2) to proportional tot(1/4) is expected and clearly corroborated by the incoherent NSE results.