J. Phys. I France
Volume 1, Numéro 2, February 1991
Page(s) 153 - 158
DOI: 10.1051/jp1:1991121

J. Phys. I France 1 (1991) 153-158

Phase separation of weakly cross-linked polymer blends

A. Bettachy1, A. Derouiche1, M. Benhamou1 and M. Daoud2

1  Groupe de Physique Théorique, Faculté des Sciences, Ben M'sick, Casablanca, Marocco
2  Laboratoire Léon Brillouin Laboratoire commun C.N.R.S.-C.E.A., C.E.N. Saclay, 91191 Gif/Yvette Cedex, France

(Received 22 November 1990, accepted 4 December 1990)

We consider the microphase separation that occurs when a mixture of two different polymers is brought to phase separation after being cross-linked. For deep quenching, microphase separation takes place, related to the competition that exists between demixion and elasticity. We consider more carefully very weak cross-linking in two cases. If the gel is assumed to be regular, the effect is present above the gelation threshold, when a gel is present, and disappears abruptly at the threshold. The characteristic size of the microphase is related to the distance between (trapped) entanglements. When the sol is present, the effect exists both above and below the gel point. The characteristic size of the microphase is of the order of the chain radius, and is much smaller than the mesh size of the gel.

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