Comparison of the tensile fracture stress of ammonium sulfate crystals and tablets


Michael Gamlen
Gamlen Tableting Ltd
Biocity Nottingham, Pennyfoot Street, Nottingham NG1 1GF, UK

J M Newton
Dept of Mechanical Engineering, University College London, London, UK

P Stanley
Wilsmlow, Cheshire, UK


Successful modelling of the compaction properties of a material require a knowledge of both bulk material and tablet properties. In this study the tensile fracture stress (TFS) of two ammonium sulfate specimens were tested – block crystals tested in line compression and beams tested in three point bend. Tablets were prepared from the block crystals (3 size fractions) without additives at a range of compaction pressures, and TFS of the tablets was measured using the diametral compression test.


Figure A: Ammoniun sulfate block crystals


Figure B: Ammonium sulfate beam crystals
length 20mm 1000 – 1410 μm









Prediction of tablet properties based on measured starting material properties would aid formulation development of tablets using small amounts of drug substance on an in- silico basis. A number of workers have studied this approach (see download). However the process of compaction is still poorly understood, particularly the roles of plastic and elastic deformation, and particle fragmentation during compaction. This study was designed to establish links between properties of the ammonium sulfate (AS) starting material and the properties of its tablets prepared without addition of any other material.

Download full article: Comparison of the tensile fracture stress of ammonium sulfate crystals and tablets
(Article filed under AAPS posters 2016 on download page)

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