Science at the Edge
Engineering Seminar
January 24th,
2014
11:30 a.m.
Room1400 Biomedical and
Physical Sciences
Building
Refreshments served at 11:15
a.m.
Norman Wagner
Alvin B. and Julia O. Stiles
Professor
Chemical & Biomolecular
Engineering
University of Delaware
STF
Technologies
LLC
Shear
thickening fluids and their applications
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.
Measurements of the
microstructure commensurate with the viscosity and normal
stress differences in
shearing colloidal suspensions provides an understanding of
how to control the
viscosity, shear thinning, and shear thickening rheological
behavior typical of
concentrated dispersions. 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 are novel field-responsive
materials that can
be engineered to be useful nanocomposites for enhanced
ballistic and impact
protection, as well as for space applications.
I will discuss the scientific basis of shear thickening
and their
applications. http://www.ccm.udel.edu/STF/
Although many applications of
concentrated suspensions are
hindered by shear thickening behavior, novel materials have
been developed
around shear thickening fluids (STFs).
Ballistic, stab and impact resistant flexible composite
materials are
synthesized from colloidal & nanoparticle shear thickening
fluids for
applications as protective materials.
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,
as will be discussed. (Phys.
Today, Oct.
2009, p. 27-32)
Bio
Norman
J. Wagner is
the Alvin B. and Julia O. Stiles Professor in the Department
of Chemical
&
Biomolecular Engineering
at the University of Delaware. He served as Chair of the
Department from 2007-2012,
and also the director of the Center for Neutron Science
(www.cns.che.udel.edu).
He leads an active research group in the fields of rheology,
complex fluids,
polymers, applied statistical mechanics, nanotechnology and
particle technology.
His research focus areas include the effects of applied flow
on the
microstructure and material properties of colloidal
suspensions, polymers, self-assembled
surfactant solutions, and combinations thereof. Prof. He
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). He
was awarded the
Siple Award in 2002 by the US Army for his development of
shear thickening
fluids for novel energy absorbing materials. This
collaborative research with
the Army Research Lab is a
major
research and
development effort toward creating novel, protective materials
(www.ccm.udel.edu/STF/).
Prof. Wagner has
authored or coauthored over 180 scientific publications and
patents and is on
the editorial boards of five 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 (2011), also
Cambridge University Press. He has developed commercial
rheo-optic instruments
as well as novel rheo-SANS instruments for investigating
nanoscale and
microscale structure in flowing systems.
More
about Professor
Wagner and his research can be found at www.che.udel.edu/wagner.
For further
information
please contact Prof. Christina Chan, Department of Chemical
Engineering and
Materials Science at [log in to unmask]
Persons with disabilities have the right
to request and
receive reasonable accommodation. Please call the Department of
Chemical
Engineering and Materials Science at 355-5135 at least one day
prior to the
seminar; requests received after this date will be met when
possible.