The role of fine particles on compaction and tensile strength of pharmaceutical powders

• We implement a novel method to investigate the role of fine particles on powder compaction and tensile strength.
• The fine particles affect the die-filling process and the early stages of compaction.
• At higher compaction forces, the difference in the relative density disappears.
• The amount of fine particles does not affect the elastic recovery and the tensile strength of compacts.

The role of fine particles on compaction of powders and the resultant compact was studied experimentally. Samples of powders were prepared by successively removing fine particles from microcrystalline cellulose and lactose monohydrate powders. This method of preparing samples is unique compared to previous studies on particle size distribution, and allows for a better analysis of the role of fine particles. For each sample, the role of fine particles on the initial relative density of the materials during die filling, the compaction profile, the in-die elastic recovery during unloading of compaction force, and the tensile strength of the corresponding tablet was investigated. It was found that the initial relative density during the die filling process and early phase of compaction decreased as a portion of the fine particles was reduced. However, this difference in the relative density during the early stage disappeared at higher compaction forces. The peak compaction pressure, elastic recovery, and the compact's tensile strength remained the same regardless of the amount of fine particles, when plotted as a function of the relative density. These results indicate that the fine particles affect the initial packing, but not the compaction of these powders and the tensile strength of the compacts.

Figure optionsDownload as PowerPoint slide