A Novel Method to Measure Powder Flow Properties Using a Small Amount of Material

One of the most frequently used bulk property characterization methods is the measurement of the change in bulk density as a function of applied normal stress; also known as compressibility.  Historically, this was measured at two conditions: loose packing (i.e. bulk density ) and maximum packing (i.e. tapped density).  More recently, the compressibility technique as performed using the Freeman Technology FT4 measures the change in bulk density as several points over a range of applied normal stress (0.5 – 15kPa).  The result of this technique is a profile, as opposed to two points, and is more reproducible due to the conditioning step in the procedure.  However, this test requires a large powder sample on the order of tens of grams.

Many applications have limited sample availability, such as pharmaceutical drug development.  Therefore, a method that uses less material is of interest.  Further, the determination of the minimum amount of material required to achieve the same results is of interest.  This work introduces a novel compressibility method that uses less than 50mg of material.  This method is validated against the FT4 compressibility test.