Gelling of Extremely Hazardous Chemicals
We have successfully demonstrated that an extremely hazardous chemical of interest
to DOD can be successfully gelled using nanoparticles. The objective is to increase
the safety of this chemical during normal handling and transport without compromising its
properties during weapon use. These two modes of operation occur under low and high shear
rates, respectively. We examined the effects of nanoparticle suspensions of various
chemical compositions and sizes in the properties of the chemical. We determined those
that were able to increase the viscosity of the chemical selectively under low shear rate
(by 5 orders of magnitudes) without any adverse effect on performance, the environment or
cost. Thus the fluid behaved as a gel during handling and transport which improved safety
considerably. Other properties of the gel were examined such as vapor pressure, density
and stability and were found to be acceptable. |
Nanofluids for Enhanced Heat Transfer
Nanofluids (NFs), essentially nanoparticles dispersed in a liquid medium, are evolving
coolant materials, which offer the potential for significant enhancements in heat transfer
rates. Three types of nanofluids have been examined in the literature - metals, ceramics
and carbon nanotubes. Recent research has established that the thermal characteristics of
all three types of nanofluids are superior to the base fluids from which NFs are produced.
The advent of nanoparticles processing methods and their unique properties (such as orders
of magnitude larger surface-to-volume ratio and ability to remain in suspension
indefinitely) spawned the idea of designer-coolant development using nanoparticles
suspended in coolants. We are currently working on optimization of thermophysical
properties and agglomeration states of nanoparticles in different nanofluids as applied to
thermal management of heat exchangers. |
Multi-Scale Modeling
Polymer matrix nanocomposites are a novel family of mineral-filled matrices that
contain relatively small amounts (typically less than 10% by weight) of nanometer-sized
particles. These nano-particles dramatically improve the performance and properties of the
polymer (e.g., mechanical strength, scratch resistance, heat stability, and much more). By
controlling the particle material, size distribution, agglomeration properties and
juxtaposition of the particles, composites can be designed to enhance the electric,
optical and mechanical properties of polymers quite dramatically. The extremely small size
of these particles, with mean characteristic lengths below 100 nanometers, offers the
potential for significantly enhanced physical properties beyond those found in the base
resin and in composite materials composed of larger micron-scale particles. We are
currently involved in developing multi-scale models to predict the mechanical properties
such as tensile, compressive modulus, shear modulus and impact strength of
nano-composites. |
