Nanocomposites (Materials)

Flexible fillers has recently been implemented as corrosion protection for post-tensioning
tendons used in bridge structures in Florida. There are two different explanations why
corrosion could take place: 1. water is able to reach the steel 2. Microbiologica l ly
Influenced Corrosion.
The aim of this research is to evaluate corrosion protection effectiveness of five differe nt
microcrystalline waxes under different environmental conditions. Specimens tested ranged
from 7-wire steel strands to single wires (12-16 cm). Another aim is the appraisal of wax
degradation by fungi species. Single wires coated with each of the investigated protection
materials, were sprayed with suspensions of three different fungi species and a mix of them.
For single wires, independent of the environmental condition the specimen with more
corrosion was Nontribos, as well as the filler coated wires contaminated with Fungi. Fungi
species investigated were able to utilize the waxes as carbon source and caused differe nt
extents of MIC.

With the goal of improving chemical detection methods for buried improvised explosive
devices (IED’s), the intention of this study is to show that functionalized nano-particles
improve the sensing properties of a polymer applied to gas sensors. The approach was
reinforcing the polymer, Nafion, with acid-functionalized carbon nanotubes (CNT’s).
Ammonia was chosen as the analyte for its similarity to IED byproducts without the
dangers of toxicity or explosion. Two sensor platforms were investigated: Quartz crystal
microbalances (QCM’s) and microcantilevers (MC’s). Preliminary evaluation of treated
QCM’s, via frequency analyzer, showed improvements in sensitivity and fast reversal of
adsorption; and suggested increased stability. Tests with coated MC’s also supported the
findings of QCM tests. Amplitude response of MC’s was on average 4 times greater
when the Nafion coating contained CNT’s. Quantitative QCM testing with gas-flow
meters showed that with CNT inclusion: the average number of moles adsorbed increased
by 35% (>1.2 times frequency response); sensitivity improved by 0.63 Hz/ppt on average; although the detection threshold decreased marginally; but reusability was
much better after extended exposures to concentrated ammonia.