Post-graduate theses
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Identifier |
000462693 |
Title |
Μελέτη νανοσύνθετων υλικών με βάση το Nafion |
Alternative Title |
Investigation of Nafion-based nanocomposites |
Author
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Καδιανάκη, Αικατερίνη Γ.
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Thesis advisor
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Αναστασιάδης, Σπύρος
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Reviewer
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Χρυσοπούλου, Κυριακή
Δαλέτου, Μαρία
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Abstract |
Polymeric nanocomposites have attracted significant attention within the scientific community
in the recent years. This increased interest is attributed to the remarkable improvements in their
inherent properties compared to those of pure polymers or the corresponding composites. In
this work, nanohybrids were developed utilizing Nafion as the main polymer; this polymer is
well known for its applications in selectively permeable membranes or as electrolyte in
electrolysis for high-purity H2 production. Alternatively, poly(ethylene oxide), PEO, which is
widely used polymer was utilized as well. Two different clay minerals of different morphology,
halloysite and sodium montmorillonite were used for the development of the hybrids.
In the first part of the study, nanocomposites were prepared utilizing two different Nafion
polymers, one in an aqueous dispersion (Nafion D1021) and one in a dispersion of
water/isopropanol mixture (Nafion D2021), together with different halloysites. The nanorods
of halloysite were used either unmodified or modified using cold plasma reactors (O2 and
Argon) during various processing times, as well as through chemical modification using
covalent bonds to enhance the interactions with the polymer. Different compositions of
nanocomposites were fabricated and all materials were characterized for their thermal stability
and structure using Thermogravimetric Analysis (TGA), X-Ray Diffraction (XRD) and
Transmission Electron Microscopy (TEM). In all cases, a large part of halloysite sediments in
the dispersion and the remaining is not sufficiently dispersed within the polymer matrix. The
results were very similar results in the cases of both the natural and the surface modified ones,
whose additional groups were not capable of improving the dispersion and the interaction of
halloysite with Nafion.
In the second part of this study, nanocomposites were synthesized utilizing Nafion and
montmorillonite, as well as PEO and modified and unmodified halloysite, to investigate their
dispersion and their thermal stability and compare them with the ones of the first part. These
nanocomposites were studied and characterized using the previously mentioned techniques; in
the case of PEO nanocomposites the polymer crystallization was investigated via Differential
Scanning Calorimetry (DSC). As far the system with montmorillonite is concerned, the
importance of the different pH between its aqueous dispersion and the dispersion of Nafion was
found to be the main reason preventing the formation of stable dispersions. On the other hand,
for the nanocomposites with PEO, it was observed that more favorable interactions exist
between the polymer and halloysite, as indicated by the quantities of the clay remaining both
in the dispersion and in the final nanocomposites.
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Language |
Greek |
Subject |
Composition |
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Halloysite |
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Montmorillonite |
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PEO |
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Polymer nanocomposite materials |
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Silicate minerals |
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Structure |
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Αλλοϋσίτης |
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Δομή |
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Μοντμοριλλονίτης |
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Πολυμερικά νανοσύνθετα υλικά |
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Πυριτιούχοι πηλοί |
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Σύσταση |
Issue date |
2024-03-21 |
Collection
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School/Department--School of Sciences and Engineering--Department of Chemistry--Post-graduate theses
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Type of Work--Post-graduate theses
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Permanent Link |
https://elocus.lib.uoc.gr//dlib/b/d/9/metadata-dlib-1708511687-255274-12315.tkl
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Views |
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