Direct observation of the transition from free to constrained single-segment motion in entangled polymer melts.
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, variant t(1/2) to proportional, variant t(1/4) is expected and clearly corroborated by the incoherent NSE results.
Wischnewski
A
A
Institut für Festkörperforschung, Forschungszentrum Jülich, Germany.
Monkenbusch
M
M
Willner
L
L
Richter
D
D
Kali
G
G