Solid-like rheological response of non-entangled polymers in the
molten state |
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Authors: | H Mendil P Baroni L Noirez |
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Institution: | (1) Laboratoire Léon Brillouin (CEA-CNRS), Ce-Saclay, 91191 Gif-sur-Yvette, France |
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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. |
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Keywords: | |
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