The Expansion of Compressed Tablets due to Moisture Sorption

Abstract

The expansion of the compressed tablets in diameter and thickness due to their sorption of moisture has been studied, using starch and microcrystalline cellulose tablets.Of the starch tablets, the values of equilibrium volume expansion were very low as compared with the equilibrium moisture contents at low relative humidities below 20%. Above this relative humidity, the values of volume expansion were approximately at 1cm3 per gram of the sorbed water.In the kinetic measurement under different conditions of relative humidity, the rate constant of moisture sorption increased with increasing relative humidity. The values of rate constants of volume expansion were approximately equal to those of moisture sorption.For the microcrystalline cellulose tablets both the rate of moisture sorption and the rate of volume expansion decreased with increasing compaction pressure in tablet preparation.