Overall the work in our IFPRI project has focused on how, moving away from model systems containing spherical colloids with near hard interactions, we can widen the range of rheological responses by changing the properties of the building blocks of the suspensions, so that even in simple formulations a wide range of behaviors can be ”built in”, i.e. obtaining formulation guidelines to do “more with less” or simplifying formulations from within. At the same time we use novel experimental methods. We also developed a constitutive model for simplified industrial suspensions, based on insights from the advanced rheological methods (stress de-convolution) and using models taking into account plastic flow behaviour using an Eyring like approach and a viscoelastic upper convected Maxwell model.
For the this second IFPRI period we now focus on :
- Particle roughness has been identified to generate surprising effects in colloidal gels and could both be tool to engineer materials from within for rheology or gravitational stability. The effect of roughness will now be explored more systematically. For gravitational stability, we will also study combined effects of roughness and shape, and investigate synergistic effects.
- A full study of the structural evolution of systems in (1) will be investigated by 4D confocal rheology, with an emphasis on understanding the yielding transition.
- To understand the role of non-central forces we would intensify the measurements of local scale mechanics using AFM (to characterize static friction) and then go to the micro mechanics of model aggregates (using optical tweezers).
- we propose to also study these systems in 2D as this also has application to engineer strong interfaces or understand what happens in protein solutions, as a model system for lock and key interactions. The 2D nature of these systems makes them also a stepping stone for doing the micromechanics not immediately on the 3D systems.
- we propose to continue the investigation of simplified industrial dispersion by industrial partners especially in light of systems with roughness and shape variations.