Characterize particles

• Surface interactions: Divided materials have a large surface area through which they interact either with each other or with the interstitial phases. Particle-particle interactions take place at the level of contacts and are due to cohesive interactions of various origins (van der Waals adhesion, capillarity, electrostatic charges. .).

• Deformability, damage, rupture: The shape and deformability of the particles (fibers, microgels, plant cells, polymer assemblies ...) strongly modulate the behavior of the divided media. In the case of elongated particles, for example, deformability limits the processability by promoting entanglement. At the scale of polymer assemblies the level of crosslinking conditions the associated mechanical properties. Using molecular-dynamics simulations or discrete-element simulations the relations between microstructure and mechanical behaviour will be determined.

• Diffusion and transport: In the context of the controlled release of active ingredients, possibly encapsulated in particles, simulations will make it possible to specify the diffusion regimes as a function of the microstructure of the polymer networks. In the case of heterogeneous catalysis, the permeability and transport properties of solutes through particle beds of complex shapes will be studied.

Determine the collective properties of particles

• Fragmentation: The mechanisms responsible for particle fragmentation will be studied with a special focus on the influence of the heterogeneity of raw materials and the presence of defects. Simulations of fracture propagation dynamics during compression or impact tests will be performed for different microstructures typical of plant and food materials. At this scale the distribution of the generated fragments and the dissipation of energy will also be investigated.

• Agglomeration: Powder agglomeration regimes will be studied as a function of particle size and fluid viscosity. In the case of grinding, we will focus on the agglomeration of very small particles which limit the kinetics of comminution.

• Flows of dense suspensions: The interaction between divided media and carrier fluids is often neglected. However, it plays a crucial role in the rheology and structuring of dense suspensions under constraints. In this context we will investigate the influence of particle density, fluid viscosity, and density ratio between grains and fluid.

• Mixing, sorting, segregation: Methods for mixing, separation and sorting of particles will be studied both numerically and experimentally, with a special attention to the case of electrostatic sorting.

Study the processes

• Describe the macroscopic mechanisms in the different transformation processes. In particular, we will focus on the influence of the modes of energy input (types of loading, dynamics ...) on the phenomena occurring during the processes and on the properties of the powders/products generated.

• Understand the impact of processes on the physical and chemical transformations of materials. Plant-based materials have a specific histological structure with strong anisotropy and complex chemistry. The properties of the generated powders result from these raw material properties, and from the mechanisms at work in the processes. When destructuring on a very fine scale, the material undergoes both physical and chemical transformations that condition the reactivity and processability of the generated powders.

• Optimize the reactivity/processability of products through combinations of physical phenomena, by proposing new unit operations based on innovative technologies, or by integrating several processes within the same unit operation (co-grinding, adjuvant ...). The objective is to design and produce size-controlled powders using the knowledge generated at the different scales.

• Propose dry refinery schemes of plant-based materials accounting for the variability of raw materials, including high-tech applications, high added value, and aiming at full recovery (without waste) of the resource.

Most of our research topics are supported by academic or industrial funding.