Droplet microemulsion and telechelic polymer: linear rheology and flow instability at high shear

摘要

Our purpose is to examine in detail the flow behaviour of model transient networks. Such a network is obtained from an o/w droplet microemulsion into which we incorporate a hydrophobically end capped hydrosoluble polymer. At high enough droplet and polymer concentrations, the system exhibits viscoelastic behaviour with quasi maxwellian stress relaxation. The variations of the elastic modulus and terminal time at the percolation threshold are discussed in the light of the Tanaka-Edwards theory: droplets rearrangements after the escape of a sticker are essential. Under steady shear, a sharp flow instability is observed. We show that it arises from a fracture like formation of a lubricating layer at the surface of the shear cell.