Understanding the roles of compaction pressure and crystal hardness on powder tabletability through bonding area - Bonding strength interplay.

Bonding area (BA) and bonding strength (BS) interplay dictates tensile strength of a tablet and, hence, tabletability. Using a series of alkali halides with mechanical properties spanning more than one order of magnitude, the role of compaction pressure and mechanical properties on tabletability is systematically investigated and explained using the BA-BS interplay. Results reveal that BA dominates the BA-BS interplay at low pressures, where more plastic powders attain higher tensile strength due to larger BA. In contrast, BS dominates the interplay at high pressures, when difference in BA between powders is minimized. Under the typical compaction pressures of 100-300 MPa, tablet tensile strength is the highest for materials with intermediate hardness, or plasticity, due to an optimal BA-BS interplay.