| Molecular Observation of Constraint Release in Polymer Melts (2006) | |||||||||||
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| PRL PHYSICAL REVIEW LETTERS week ending JUNE Molecular Observation Constraint Release Polymer Melts Zamponi Wischnewski Monkenbusch Willner and Richter Institut fur Festkorperforschung Forschungszentrum Julich Julich Germany Likhtman Department Applied Mathematics University Leeds Leeds United Kingdom Kali and Farago Institut Laue Langevin Avenue des Martyrs Grenoble Cedex France Received March published June The dynamics binary polymer blends few labeled long chains successively shorter matrix chains has been investigated neutron spin echo NSE spectroscopy For the rst time the effect constraint release the chain relaxation has been directly observed microscopic scale Decreasing the matrix chain length reduces the topological con nement until uncon ned Rouse motion observed when the matrix chains are too short con the long chain tube Whereas analytical description the effect not yet available new simulation based the slip link model shows perfect agreement with the NSE data over the full range matrix molecular weights DOI PhysRevLett PACS numbers Ex The dynamics linear polymer chains the melt strongly depends the chain length For short unentangled chains and for any length short times the dynamics determined balance viscous and entropic forces which can described the Rouse model Here the chains interact solely local friction with heat bath representing the neighboring chains For long chains topological chain chain interactions terms entanglements become important and are domi | |||||||||||
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