Use of jump-tests for the characterization of the viscoplastic behavior of pharmaceutical powders during compaction
Langue
EN
Article de revue
Ce document a été publié dans
Powder Technology. 2022-05, vol. 404, p. 117406
Résumé en anglais
Strain rate sensitivity (SRS) corresponds to the influence of the compaction kinematic on the powder behavior during compaction and on the final tablet properties. Several physical phenomena can explain the SRS like ...Lire la suite >
Strain rate sensitivity (SRS) corresponds to the influence of the compaction kinematic on the powder behavior during compaction and on the final tablet properties. Several physical phenomena can explain the SRS like viscoelasticity or viscoplasticity. This work focuses on the case of viscoplasticity, especially by choosing products that are known to present little viscoelasticity. First, monotonic compression at different speed were performed and demonstrated that viscoplasticity was not constant during the whole compaction. Then, Jump tests showed the existence of transient phenomena during speed changed that are similar to phenomena described in the literature as dynamic strain aging. Introduction of long dwell-times during jump tests also indicated that all the products presented a stress relaxation even at slow speed. This was confirmed on long relaxation experiments (10h). As a consequence, for viscoplasticity, even compactions performed at very slow speed must be considered as dynamic.< Réduire
Mots clés en anglais
Viscoplasticity
Compaction
Speed
Strain rate sensitivity
Mechanical behavior
Tablet
Unités de recherche