(220e) From Particle to Process Predicting Breakage of Structured Particles

The breakage of consumer products prior to packing or due to consumer use is a common issue, especially with structured particles. This is a complex problem spanning several size scales. On the particle scale, the structured particles can exhibit preferred breakage zones or modes due to the shape and morphology of the particles. Potato chips may break along the plane of greatest bending moment. Ice cream cones may break when the hoop stress around the perimeter of the cone exceeds a critical value. A bilayer tablet may break at the junction between two dissimilar materials. All of these breakage effects are particle structure effects which require an understanding of stresses and strains formed at the particle scale as well as solving FEM problems describing the distribution of stress in the structured particles. However, after the initial breakage of structured particles, the fragments may not have any preferred breakage modes or zones and standard breakage modeling can be useful to determine the secondary mode of breakage. Most modeling efforts in particle breakage are based on continuum descriptions of the breakage process involving many particles. However, a link must be developed between the particle scale – including the effect of structure breakage effects and when to apply them. To solve the breakage problem the effects of handling and processing on the breakage of particles must be determined. In every process step, or during the consumer use step, the material undergoes a unique set of stress-strain events coupled with a unique set of impact events. Often these stress-strain and impact events can be computed given a description of the process. However, a link must be made between stress-strain events as well as impact events and particle breakage. If this link can be made, then the breakage in a prescribed process can be determined so that process steps to reduce breakage can be applied. Using both continuum and structured particle modeling to describe breakage, coupled with stress-strain and impact breakage events, engineers can to fix breakage problems by changing the particle or by changing the process. The development of general methods and scientific frameworks to describe this multiscale effect is the discussion of the paper. The effect and use of breakage on a structured particle will be examined. The use of standard continuum based methods for non-structured particles will be examined. The link between stress-strain and impact events on breakage will be examined, as well as the impact of processing on stress-strain and impact events.