Fu Li, Rhéologie des polymères dans les contacts confinés : tribologie des interfaces étudiées par un nouveau dispositif couplant FRAPP et nano- tribologie (2015)

This work deals with the development of a new experimental technique and its application to study the rheology of a highly confined and sheared interfacial zone involved in the sliding of a rigid tip on a polymer suface. This tribological work has been conducted gradually from the mesoscopic scale to the nanoscale. To highlight the behavior of the cohesive zone, we studied an interpenetrating polymer network system (INPs) CR39-PMMA. Thanks to their adjustable properties, we may use the INPs as a substrate to study the interfacial zone by easily varying the rheological parameters.
To study the rheological properties in the interfacial zone, the phospholipid layers of DSPC have been chosen as model material. The structures have been studied by the neutron reflectivity experiments. We show that the structure of supported layers of DSPC is robust, and the relative humidity plays a key role on it. Sliding tests on the DSPC layers reveals the influences of mechanical and environmental parameters on the shear stress. The development of NanoTribo-FRAPP allows to characterize the shear conditions of DSPC layers, with the measurements of local velocity of these of nanoscale molecular layers. This gives us access to estimate the slip planes as a function of imposed velocity.