Compaction of plastic powders

A number of equations have been proposed in the literature to fit the data obtained during compaction of powders. Macroscopic parameters such as the relative density [1], the 'relative volume of the compact' [2], or the 'fractional volume compaction' [3] are often plotted versus the pressure applied to the sample. Most of these equations are based upon kinetic considerations [4] and are finally more or less empirical in nature. Among them, the equation proposed by Heckel [5] has been used frequently: