The relationship among tensile strength, Young's modulus, and indentation hardness of pharmaceutical compacts

Abstract

Mechanical properties of pharmaceutical materials, e.g., Young's modulus (E), indentation hardness (H), and tensile strength (σt), play an important role in powder compaction process. However, few studies investigated the relationship among these parameters and consequence for tablet compression. Using microcrystalline cellulose, a plastic material, and dibasic calcium phosphate anhydrate, a brittle material, as well as their binary mixtures, we systematically examined the relationship among the three properties. It was found that Young's modulus was proportional to indentation hardness (H/E≈0.036) regardless of the composition and compaction pressure. For a given material, tensile strength was also proportional to E and H but the relationship varied with materials. Higher E and H were required to attain the same σt for a more brittle material.