Polymeric composites.

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.

Luminescent lanthanide containing coordination polymers and metal-organic frameworks hold great potential in many applications due to their distinctive spectroscopic properties. While the ability to design coordination polymers for specific functions is often mentioned as a major benefit bestowed upon these compounds, the lack of a meaningful understanding of the crystal engineering and luminescence in lanthanide coordination polymers remains a significant challenge toward functional design. Currently, the study of luminescence attributed to these compounds is based on the antenna effect as derived from molecular systems, where organic antennae are used to facilitate lanthanide-centered luminescence. This molecular based approach does not take into account the unique features of extended network solids, particularly the formation of band structure. By comparing molecular and band-based approaches, it was determined that the band structure of the organic sensitizing linker needs to be considered when evaluating the luminescence of lanthanide coordination polymers. This new model, as well as work on the crystal engineering and sensor applications of these materials will be presented.

In fabrication of nanoparticle-reinforced polymers, two critical factors need to be
taken into account to control properties of the final product; nanoparticle
dispersion/distribution in the matrix; and interfacial interactions between nanoparticles and
their surrounding matrix. The focus of this thesis was to examine the role of these two
factors through experimental methodologies and molecular-level simulations. Carbon
nanotubes (CNTs) and vinyl ester (VE) resin were used as nanoparticles and matrix,
respectively.
In a parametric study, a series of CNT/VE nanocomposites with different CNT
dispersion conditions were fabricated using the ultrasonication mixing method. Thermomechanical
properties of nanocomposites and quality of CNT dispersion were evaluated.
By correlation between nanocomposite behavior and CNT dispersion, a thermomechanical
model was suggested; at a certain threshold level of sonication energy, CNT dispersion would be optimal and result in maximum enhancement in properties. This
threshold energy level is also related to particle concentration. Sonication above this
threshold level, leads to destruction of nanotubes and renders a negative effect on the
properties of nanocomposites.
In an attempt to examine the interface condition, a novel process was developed to
modify CNT surface with polyhedral oligomeric silsesquioxane (POSS). In this process, a
chemical reaction was allowed to occur between CNTs and POSS in the presence of an
effective catalyst. The functionalized CNTs were characterized using TEM, SEM-EDS,
AFM, TGA, FTIR and Raman spectroscopy techniques. Formation of amide bonds
between POSS and nanotubes was established and verified. Surface modification of CNTs
with POSS resulted in significant improvement in nanotube dispersion. In-depth SEM
analysis revealed formation of a 3D network of well-dispersed CNTs with POSS
connections to the polymer. In parallel, molecular dynamics simulation of CNT-POSS/VE
system showed an effective load transfer from polymer chains to the CNT due to POSS
linkages at the interface. The rigid and flexible network of CNTs is found to be responsible
for enhancement in elastic modulus, strength, fracture toughness and glass transition
temperature (Tg) of the final nanocomposites.