Comminution

We study the comminution of solid and the emulsification of liquid particles in hierarchical approaches stretching from single particles at well-defined stress conditions to the analysis of stressing conditions in mills and their operational behavior. At the single particle level, we use SEM-based micromanipulation for the determination of mechanical particle properties and single particle impact testing for the measurement of fracture probability and breakage functions. With respect to mills, we mainly focus on stirred media mills in the liquid phase and air classifier mills (hammer and opposed fluidized bed mills). Our strategic approach targets the determination of mill functions to describe the stress energy and number distributions in dependence of operational parameters, and material functions which address the reaction of the particles to the applied stress, i.e. breakage probability and breakage distributions as function of intrinsic material parameters.

Currently, the following material systems are studied:

• Identification of the true grinding limit for pharmaceutical nanoparticles
• Polymers for additive manufacturing
• Delamination of 2D materials such as graphene
• Glass particles above and below the brittle-ductile transition, e.g. bioglass as biomaterial and electrode materials for batteries
• Melt emulsification of polymers and pharmaceutical active compounds