A new perspective on the mechanical evaluation of granular material

Abstract

The mechanical strength of granules is an important parameter to be determined prior to any further downstream formulation processing. It is important to have a good gauge on the granule integrity to forecast any foreseeable powder issues associated with the material processability such as segregation, content uniformity, and material flow-ability. In this study, a systematic methodology has been developed to quantify the integrity of these granules subjected to a low frequency acoustic field to arrive at the Granule Integrity (GI) index. This methodology has been compared to existing well-established bulk characterization techniques reported in the literature such as Heckel analysis, Kawakita analysis, and Young’s modulus for four different processed samples. Heckel analysis is more amenable to examine the material deformability while Kawakita analysis is better suited to understand the mechanics of granular material. Individual granule strength measurements to determine Young’s modulus often show large variations across the bulk sample. The GI index in conjunction with the Kawakita analysis provides us with more mechanistic insight and understanding into the formation of these granules from a processing perspective. This paper shows the benefits of using the GI index as a practical and direct methodology to characterize the GI of bulk samples in an industrial setting.

Keywords::

• Granule Integrity index
• material characterization
• granule strength
• Heckel
• Kawakita
• bulk behavior
• acoustic
• Young’s Modulus
• material properties
• mechanical strength

Acknowledgments

The authors wish to thank the following members: Deniz Erdemir, Donald Kientzler, Shih-Ying Chang and San Kiang for their collaboration on this project. Special thanks to Shasad Sharif for the analytical support.

Declaration of interest

The authors are employed by The Bristol Myers Squibb Company.