Acoustic emission of pharmaceutical powders during compression

Measuring acoustic emission, seems to be a useful tool to understand and distinguish phenomena occurring during powder compaction of pharmaceutical products. These phenomena generally considered are granular rearrangement, fragmentation and visco-plastic deformation of grains or granules. Other results such as specific area and porosity evolution versus compaction pressure provide valuable information on domains where whether fragmentation or viscoplastic deformation are predominant. Therefore acoustic emissions can be related with phenomena occurring in the granular medium during compaction. For instance, brittle products like aspirin or saccharose produce strong acoustic emission whereas, starch, with a highly visco-plastic behaviour, produces small intensity acoustic emission.