Cavitation-induced force transition in confined viscous liquids under traction

We perform traction experiments on viscous liquids highly confined between parallel plates. At small separation rates, we observe a simple response with a smooth decrease of the force. Dramatic changes in the force response occur at high separation rates, with the appearance of a force plateau followed by an abrupt drop. By direct observation in the course of the experiment, we show that cavitation is responsible for the latter features which are reminiscent of the utmost complex behaviour of adhesive films under traction. Surprisingly enough, this is observed here in a fluid material