Investigation of the slip transition at the melt polymer interface

We present a detailed experimental investigation of the effect of molecular parameters on the onset of strong slip at the wall for polydimethylsiloxane melts flowing against silica surfaces on which a weak density of polymer chains are anchored by adsorption. The observed variation of the critical velocity for the onset of strong slip V * ∝ N −1.09 P −3.2 , with N and P the polymerisation indices of surface and bulk chains, respectively, and the wide range of the non-linear friction regime above V * strongly support the description of the dynamic de-coupling between the surface and bulk chains in terms of progressive disentanglement.