UWINNFM Workshop Rheometry II location:Miskin Manor, Wales date:14-16 April 2003
The conformational and dynamical behavior of viscoelastic polymer melts and solutions close to solid boundaries is of great interest for the polymer processing industry. In particular, when the length scale of the flow approaches microscopic scales, boundary effects such as wall-slip, cohesive and adhesive failure occur on the same scale as the overall deformation of the bulk sample and their impact on the measured rheological properties can no longer be neglected. In particular, the yielding and viscometric behaviour of a fluid in a narrow gap cannot be simply deduced from the flow behavior of a bulk sample.
The aim of this paper is therefore to introduce new investigations on complex emulsions and polymeric fluids with a new type of microrheometer. The Flexure-based Microgap Rheometer (FMR) is a shear-rate-controlled device capable of measuring the shear stress in a plane Couette type sliding plate setup with directly-controlled gaps between 1 m and 200 m over 5 decades of shear rate. This configuration then allows us to determine the microgap-dependent flow behavior of complex fluids such as mayonnaise and cosmetic emulsions which exhibit yield stress characteristics.