title: Molecular observation of constraint release in polymer melts.
abstract: The dynamics of binary polymer blends of few labeled long chains in successively shorter matrix chains has been investigated by neutron spin echo (NSE) spectroscopy. For the first time the effect of constraint release on the chain relaxation has been directly observed on a microscopic scale. Decreasing the matrix chain length reduces the topological confinement until unconfined Rouse motion is observed, when the matrix chains are too short to confine the long chain in a tube. Whereas an analytical description of the effect is not yet available, a new simulation based on the slip-link model shows perfect agreement with the NSE data over the full range of matrix molecular weights.
authors.affiliation: Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Zamponi
authors.forename: A
authors.initials: A
authors.lastname: Wischnewski
authors.forename: M
authors.initials: M
authors.lastname: Monkenbusch
authors.forename: L
authors.initials: L
authors.lastname: Willner
authors.forename: D
authors.initials: D
authors.lastname: Richter
authors.forename: A E
authors.initials: AE
authors.lastname: Likhtman
authors.forename: G
authors.initials: G
authors.lastname: Kali
authors.forename: B
authors.initials: B
authors.lastname: Farago
mesh_terms: D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D008970:Molecular Weight; D020959:Polyethylene / Q000032:analysis* / Q000737:chemistry*; D011108:Polymers / Q000032:analysis* / Q000737:chemistry*; D044366:Transition Temperature
chemical_list: D011108:Polymers; D020959:Polyethylene