Jovana Radojevic, Antonios Zavaliangos

There has always been a desire to understand the behavior of powder mixtures from that of individual components. Prior work on this topic aimed on deriving the properties of the mixtures based on interpolation of the properties of the components. Although this is tempting, there are many mixtures that defy such simple approaches.  In this work sodium chloride (NaCl) and starch were used as a model mixture, which has been shown to exhibit a mechanical strength well below the interpolated strengths of its components.  The evolution of mechanical behavior of starch and sodium chloride (NaCl) mixture tablets after compaction and its interaction with moisture was studied in detail.  It was shown experimentally that the strengths of NaCl-starch mixtures and NaCl tablets evolved in an opposite way after compaction. When stored at an RH of 60% NaCl tablets strengthened with time, while NaCl-starch mixtures weakened.  A mechanistic understanding of this effect was validated using discrete element modeling (DEM) and a novel experimental approach was developed based on the insight from DEM simulations.  This knowledge was applied on the optimization of strength of NaCl-X mixtures and it was demonstrated experimentally that the strength of various NaCl-X mixtures increases with progressively lower differences in the elastic modulus between the two components.

Biosketch: Antonios Zavaliangos

Antonios Zavaliangos is the A. W. Grosvenor Professor of Materials Science and Engineering at Drexel University. He received a Diploma in Mechanical Engineering from the National Technical University of Athens, Greece (1986) an MS in Civil Engineering and Engineering Mechanics from Columbia University in 1987 and his Ph.D. in mechanical engineering from MIT (1992). He has been with the faculty of Materials Science and Engineering at Drexel University since 1992.