Melt fracture of entangled polymers*
Institut Curie, Centre de Recherche, 26, rue d’Ulm, 75005, Paris, France
Accepted: 16 May 2007
Published online: 4 June 2007
We construct a model for a slippage plane in a sheared melt, based on a balance between reptation bridging and shear debonding. The resulting state could show up at rather low shear rates and be locally stable. But it is not easy to nucleate: the conventional entangled state is also locally stable. We propose that slippage occurs on solid walls: either at the container surface, or on dust particles floating in the melt. Slippage at solid/melt interfaces was studied (experimentally and theoretically) long ago. There is a critical stress σ* for slippage: our estimate (for strong adsorption of melt chains on the solid) gives ˜* ˜ 1/3 (plateau modulus) for typical cases. Thus, melt fracture is expected at moderate stresses, in agreement with observations by S.Q. Wang and coworkers.
PACS: 61.25.Hq Macromolecular and polymer solutions; polymer melts; swelling – / 62.10.+s Mechanical properties of liquids –
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2007