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. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection
| Identifer | oai:union.ndltd.org:fau.edu/oai:fau.digital.flvc.org:fau_33487 |
| Contributors | Sabet, Seyed Morteza (author), Mahfuz, Hassan (Thesis advisor), Florida Atlantic University (Degree grantor), College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering |
| Publisher | Florida Atlantic University |
| Source Sets | Florida Atlantic University |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation, Text |
| Format | 192 p., application/pdf |
| Rights | Copyright © is held by the author, with permission granted to Florida Atlantic University to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder., http://rightsstatements.org/vocab/InC/1.0/ |
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