IFPRI has traditionally divided particle technology into five parts: dry systems, wet systems, particle formation, particle size reduction, and characterization.  Schematically, characterization lies at the center, and the projects that comprise it are relevant to the other four areas.  These projects explore both the properties of particles and powders, and the tools and methods used to measure those properties.

Particle processes are intrinsically multi-scale, and it is impossible to predict product performance or design processes without explicitly considering the particle, bulk powder, and macroscopic scale.  Characterization provides the tools to measure the structure of a system at all three length scales and is essential to understanding how they are interrelated. 

IFPRI uses an expansive and inclusive definition of characterization.  It includes evaluation of morphology, mechanical properties, surface chemistry, electrical charge, and chemical composition (particularly the distribution of distinguishable chemical moieties).  Measurements range from supramolecular (molecular clusters, e.g. crystal nuclei or unit cells) through single-particle and constitutive powder properties to the process scale.


IFPRI Funded Projects

IFPRI has provided over $1 million research funding in area of particle and powder characterization.  The projects that have been funded are listed in Appendix A.  The work falls into five broad categories:

Electrostatics:  the measurement of charge on particles and its impact on powder properties has been a topic of interest since IFPRI’s inception, and it continues today.  This includes projects focused on measurement of single-particle charge and understanding the mechanism of contact charging (Singh, 1982; Yamamoto and Matuyama, 2003).  Leschonski (1985) investigated electrostatic classification of particles.  Currently, Castellanos is developing techniques for studying how electrostatic charge affects the packing of particles.

Interparticle Forces: a number of projects have been funded that utilized direct measurement of interparticle force, such as by atomic force microscopy, to characterize particle interactions in different environments.  These include work by Higashitani (2002) that measured interactions between hydrophilic and hydrophobic surfaces in aqueous and organic liquids and more recently by Craig (2013) to measure forces between mineral surface at very high ionic strength and pH. 

Morphological Analysis:  measurement of particle size, shape, and structure are fundamental to understanding powder behavior.  IFPRI-funded work in this area includes development of reproducible polydisperse particle size standards (Masuda, 1997), characterization of particle surface microstructure by AFM (Higashitani, 2002), measurement and description of 3-dimensional shape (Pirard, 2009), and development of descriptors of the structure of multicomponent particles (Kohlus, ongoing).

Process Tomography:  over a 12-year period, IFPRI funded projects to develop on-line process-scale measurements of powder structure.  This included development of tomographic methods for visualizing powders in fluidized beds (Beck, 1998), and the combination of sensors to visualize the structure of flowing suspensions in pipes (Williams, 2003).

Mechanical Properties: An early IFPRI project developed methods for measuring the strength of polymeric agglomerates as a function of temperature (Sekiguchi and Tohata, 1982).  Jimbo (1988) continued this theme in a study of powder mechanical properties at high temperatures. 

This summary includes only those projects that IFPRI formally designated as characterization projects.  The actual number of projects in which novel particle, powder, and dispersion characterization tools were developed is much larger, as new characterization tools are frequently developed in projects that fall into the other categories. 

In addition to research projects, IFPRI has funded a large number of reviews in particle and particulate system characterization.  These are listed in Appendix B

Appendix A:  IFPRI-funded Projects

  • Development of high resolution electrostatic probe for measuring charge on individual particles, Singh (1982)

  • Temperature dependence of agglomerate strength of polymeric particles, Sekiguchi and Tohata, 1982)

  • Electrostatic classification of particles, Leschonski (1985)

  • Measurement of mechanical properties of powders at high temperatures, Jimbo (1988)

  • Development of particle size standard materials, Masuda (1997)

  • In-situ characterization of particle surface microstructure and interparticle force by AFM, Higashitani (2002)

  • On-line characterization of particulate suspensions using a multi-sensor approach, Williams (2003)

  • Contact charging of individual particles, Yamamoto and Matsuyama (2003)

  • 3D particle size and shape characterization, Pirard (2011)

  • Measurement of surface interactions between mineral surfaces at high ionic strength, Craig (2013)



    Appendix B: IFPRI-funded Reviews


  • Particle morphology analysis, Beddow (1982)

  • High-temperature electrostatics, Bailey (1987)

  • Zetapotential – measurement and application from a practical perspective, Scales and Johnson (1988)

  • Characterization of fine particles, Leschonski (1989)

  • Production of spherical submicrometer standard powders, Ranade and Varga (1994)

  • Process tomography, Beck, Dyakowski, Williams (1996)

  • Instrumentation for dense gas-solid flows, Louge (1997)

  • Coupling particle size measurements for control and monitoring of particulate processes, SEvick-Muraca (1997)

  • Interparticle forces in gaseous and liquid environments and their influence on powder dispersion, Schubert (1997)

  • Particle electrostatics, Yamamoto and Matsuyama (1998)

  • Testers for measuring flow properties of bulk solids, Schwedes (1999)

  • Characterization of porous particle systems, Kendall (1999)

  • Particle morphology characterization, Pons (2002)

  • Measuring particle size at high concentration, Scarlett (2003)

  • Non-invasive techniques for particle characterization, Smith (2003)

  • Characterization of surface free energies and surface chemistry of solids, Etzler (2003)

  • The shape of powder particles and its influence on powder handling, Podczeck (2003)

  • Surface chemistry at inorganic solid/liquid interfaces containing high electrolyte concentrations, Rosenholm and Kosmulski (2003)

  • 3-dimensional particle characterization, Pirard, (2007)

  • Characterization of interparticle forces for predicting powder flow, Israelachvili (2007)

  • Powder structure characterization, Stepanek (2006)

  • Agglomerate and aggregate strength, Salman (2008)

  • 3-dimensional pore characterization and pore-scale transport modeling in earth sciences, Cnudde (2014)