Compression characteristics of powders: radial die wall pressure transmission and density changes

Abstract

An instrumented single punch tablet machine was used to study the relations between axial pressure, radial die wall pressure and density changes in beds of powder undergoing compression. Aspirin, sodium chloride, paracetamol, paracetamol-polyvinylpyrrolidone and sucrose crystals were examined. The development and transmission of radial pressure during loading and unloading of the bed is discussed in relation to yield and elastic behaviour of the powder. The relation between mean stress and relative density of the compact is explained on the basis of plastic flow and/or crushing of the particles. Differences in stress vs density relations due to difference in particle size of sucrose were due to initial packing conditions in the die and not to differences in pressure transmission.