The Use of Stress Relaxation Trials to Characterize Tablet Capping

Abstract

A new method is described for estimating capping risks due to the entrapment of air during compression.

For this, the curves obtained during a stress relaxation test were analysed using a WISCHERT model.

Two processing modes of computation from experimental data made it possible to characterize the stress relaxation of each product or mixture of products by a sum of two or three exponentials.

The first exponential represents a more or less rapid structure relaxation. When the quantity of fines particles is too great, the structure relaxation is slowed down by the entrapped air as soon as constant deformation is applied.