Etude expérimentale des propriétés viscoélastiques des comprimés pharmaceutiques
The tablet is the most common pharmaceutical form. It is obtained by a die compaction process of powder mixtures. Even if this process is widely used for more than a century, manufacturing problems are still to be solved. Among them, capping corresponds to the breakage of the top of the tablet during or after the ejection. Mechanisms for this phenomenon have been proposed, but its prediction is still challenging. One of the reasons is the lack of a robust mechanical model for the behavior of the tablet that would make it possible to have a quantitative estimation of the stresses on the tablet during the whole compaction cycle. Classically, for example in FEM simulations, the mechanical behavior of the tablet is described using an elasto-plastic model like the Drucker Prager Cap model coupled with linear elasticity. This model is time independent. Nevertheless, numerous studies have shown that time dependent behaviors, like viscoelasticity, play an important role during compaction.