The stick–slip transition in highly entangled poly(styrene-butadiene) melts

We study the interfacial slippage of highly viscous polymer melts in a plane Couette cell by combining stress measurements and optical determination of sliding velocities (Fluorescence Recovery After Photobleaching). This enables us to observe the apparition of stick–slip instabilities in a narrow shear rate range whose limits are governed by the molecular characteristics of both the bulk and surface anchored polymer chains. A qualitative interpretation of these results will be given in terms of extraction and re-entanglement of the surface anchored chains from the bulk ones as well as a necessary criterion for the apparition of these instabilities. Experiments exploring the kinetics of the stick–slip regime appear to be a simple and promising way to investigate interfacial dynamics and to estimate the characteristic times involved.