title: Solid-like rheological response of non-entangled polymers in the molten state.
abstract: We show that non-entangled polymers display an elastic-like behaviour at a macroscopic scale (probed at some 0.100 mm thickness) up to at least hundred degrees above the glass transition temperature. This observation, found under non-slippage conditions, both for side-chain liquid crystalline polymers and ordinary polymers, is in contradiction with the typically found flow behaviour of polymer melt. Our measurements were carried out with a conventional rheometer at thicknesses of several tenths millimetres. Thus, we were probing bulk properties. The observed elasticity supposedly implies that even in the melt the chains experience a cohesive effect of macroscopic distances, involving collective motions over time scales longer than the individual relaxation time of an individual polymer chain. The detection of such a solid-like property of molten non-entangled polymers is of considerable importance for a better understanding of the polymer dynamics.
authors.affiliation: Laboratoire Léon Brillouin, CEA-CNRS, Ce-Saclay, 91191, Gif-sur-Yvette, France.
authors.forename: H
authors.initials: H
authors.lastname: Mendil
authors.forename: P
authors.initials: P
authors.lastname: Baroni
authors.forename: L
authors.initials: L
authors.lastname: Noirez