title: Powder flow studies III: tensile strength, consolidation ratio, flow rate, and capsule-filling-weight variation relationships.
abstract: The tensile strength of consolidated powder beds was studied by applying a series of loads to the surface of the powder beds in a tensile tester. The results were plotted as tensile strength versus consolidation pressure. The linearity of these plots suggests a direct relationship between tensile strength and consolidation pressure. The following plots gave linear relationships: (1) tensile strength versus consolidation ratio, (b) tensile strength versus coefficient of variation of the filled weight of the capsules, and (c) logarithm of the tensile strength versus logarithm of the flow rate. These results suggest a direct relationship between tensile strength and consolidation ratio and their usefulness in studying powder flow. The physical significance of the empirical equation used in consolidation studies was explored. A comparison of the empirical equation with a theoretically derived equation, under certain assumptions, suggests that the consolidation ratio is a function of the ratio of the initial volume to the net volume and a function of the coefficient of Rankine. The coefficient of Rankine is a function of the angle of internal friction in the static powder bed.
mesh_terms: D002214:Capsules; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D011208:Powders; D013678:Technology, Pharmaceutical; D013718:Tensile Strength
chemical_list: D002214:Capsules; D011208:Powders