Abstract: Shear thickening colloidal and/or nanoparticle suspensions are commonly encountered in chemical and materials processing, and are also the basis of a technology platform for advanced, field responsive nanocomposites. In this presentation, I will review some of the experimental methods and key results concerning the micromechanics of colloidal suspension rheology. Micromechanics is the ability to predict the properties of complex systems from a colloidal or microscopic level description of the structure and forces. A fundamental understanding of colloidal suspension rheology and in particular, shear thickening, has been achieved through a combination of model system synthesis, rheological, rheo-optical and rheo-small angle neutron scattering (SANS) measurements, as well as simulation and theory (Colloidal Suspension Rheology Mewis and Wagner, Cambridge Univ. Press, 2012).
Shear thickening fluids (STFs) are novel field-responsive materials that can be engineered to be useful nanocomposites for enhanced ballistic and impact protection, puncture resistant medical gloves, energy absorbing materials for mitigating impacts and concussions, as well as in systems for mitigating micrometeoroid and orbital debris threats in space applications. The development of commercial applications of STFs will be discussed. The rheological investigations and micromechanical modeling serve as a framework for the rational design of STF-based materials to meet specific performance requirements not easily achieved with more conventional materials. (Phys. Today, Oct. 2009, p. 27-32) I will illustrate some technological applications of STFs under commercial development, including use in astronaut protection and application in the manned missions to the Moon and Mars, and review ongoing experiments on the International Space Station to improve their technology readiness.
Biosketch: Norman J. Wagner is the Unidel Robert L. Pigford Chair in Chemical Engineering at the University of Delaware, with affiliated faculty appointments in Physics and Astronomy, and Biomechanics and Movement Science. He is President of the Society of Rheology (American Institute of Physics Member Society), is the co-founder and director of the Center for Neutron Science www.cns.che.udel.edu, and served as Chair of the CBE Department from 2007-2012. He was elected to the National Academy of Inventors in 2016 and the National Academy of Engineering in 2015. He leads an active research group with focus on materials for manned space exploration, the rheology of complex fluids, neutron scattering, colloid and polymer science, applied statistical mechanics, nanotechnology and particle technology. His research interests include the effects of applied flow on the microstructure and material properties of colloidal suspensions, polymers, self-assembled surfactant solutions, and complex fluids. Prof. Wagner earned his Bachelors degree from Carnegie Mellon and Doctorate from Princeton University, was an NSF/NATO Postdoctoral Fellow in Germany, and a Director’s Postdoctoral Fellow at Los Alamos National Lab prior to joining the University of Delaware in 1991. He was named a Senior Fulbright Scholar (Konstanz, Germany) and served as a guest Professor at the ETH, Zurich (1997) and the University of Rome (2004). His recent awards include Sustained Research Prize of the NSSA (2018), election as Fellow of the AAAS (2015), the Bingham Medal of the Society of Rheology (2014), election as Fellow of the Neutron Scattering Society of America (2014), and the AIChE PTF Thomas Baron Award (2013). He was awarded the Siple Award in 2002 by the US Army for his development of shear thickening fluids for novel energy absorbing materials. Prof. Wagner has authored or coauthored over 200 scientific publications and patents, and has served on the executive committee of the Neutron Scattering Society of America, as well as Section Editor for AIChE Journal (Soft Matter), in addition to serving on the editorial boards of four additional international journals. He has co-authored a textbook (2008) on Mass and Heat Transfer for the Chemical Engineering series of Cambridge University Press, as well as Colloidal Suspension Rheology (2012), also Cambridge University Press. Patented and commercially developed scientific instruments include rheo-optic instruments (TA Instruments) as well as novel rheo-SANS instruments for investigating nanoscale and microscale structure in flowing systems currently available at the NIST Center for Neutron Research and the Institute Laue Langevin D22, Grenoble, France. Prof. Wagner co-founded STF Technologies LLC in 2003 to commercialize his inventions for personal protective equipment and astronaut protection for NASA. More about Professor Wagner and his research can be found at www.cbe.udel.edu/wagner.