Hybrid polymer matrix systems with micro- and nano- carbon fillers (Doctoral thesis)

Στημονιάρης, Αδάμ

A systematic study of the changes in the final properties and dynamics of polymer nanocompositematerials with regard to the structure, morphology, size and content of the inclusions and the fillers’surface modification as well. The polymeric matrix used was a thermosetting epoxy resin (ER),produced by in situ polymerization in the presence of triethylenetetramine (TETA) as a curing agent,thus avoiding additional steps of solvents’ use and removal. Carbon nanoparticles of different shapeand structure (form) and fly ash were used as inclusions, as well as inorganic fillers added into thepolymeric matrix.The mobility of a polymer interfacial layer, a few nanometers near the surface of inclusions is differentfrom that for a pure polymer. The study of carbon-filled ER samples of different structures as adispersed phase, allowed the study of the influence of the fillers morphology on the molecular matrixmobility. The dynamic coexistence, including interfacial constraints and free volume changes, leads toa varying balance of factors depending on many factors, influencing accordingly the dynamical andgeneral behavior of the materials.Surface treatment of carbon based fillers and fly ash with organosilane agent has been found toimprove the interface and strength of the interaction. The strong interaction improves the fillerdispersion and facilitate the transfer of dynamic loads from matrix to filler, leading to an increase of themodulus of elasticity. Surface treatment reduces the particle agglomeration and aggregation. Residualtraces of filler matter around the filler particulates in the case of the modified fly ash filler have beenobserved.Hybrid composites were examined for the synergy of the inclusions within the matrix. Data fromspectroscopic techniques showed complete incorporation of hybrid systems into the matrix, in theabsence of indications for characteristic nanostructure absorbances. Proper exfoliation into individualsheets of particular fillers lead to amorphous hybrid nanocomposites exhibiting adequate dispersionwithin the matrix.The overall dielectric behavior and the electromagnetic shielding mechanism of hybrid complexesdemonstrated that combined addition of modified phylosilicate montmorillonite (CL30B, 2D-structure)into the matrix led to more efficient damping of electromagnetic waves compared to that possible uponincoroporation of amino-modified nanotubes (1D-structure) alone. Further, the change in conductivity inhybrid composites, ER/CL30B/mMWCNTs and ER/CL30B/CB, confirms synergy effects between fillersand the contribution of particle shape and size to the final properties.To test the use of nanocomposites and hybrid composites for various environmental and technologicalapplications, the attained physicochemical properties are considered on the basis of a "useful workingrange" (UWR) assessment index; the latter index focuses on the temperature range that allows fornearly fixed ( 20%) properties and allows for the evaluation of the potential of the prepared materialsfor practical, state-of-the-art applications.
Alternative title / Subtitle: σύνθεση, δυναμική συμπεριφορά και εφαρμογές
composition, dynamic behavior and applications
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Πολυτεχνική Σχολή. Τμήμα Μηχανικών Επιστήμης Υλικών
Subject classification: Υβριδικά συστήματα
Keywords: Υβριδικά συστήματα,Νανοσύνθετα,Εποξειδική ρητίνη,Πληρωτές άνθρακα,Φυλλόμορφα εγκλείσματα,Ιπτάμενη τέφρα,Νανοδιάσταση,Διεπιφάνεια,Οργανο-τροποποίηση,Μηχανισμοί χαλάρωσης,Χρήσιμο εύρος εργασίας,Hybrid composites,Nanocomposites,Epoxy resin,Carbon based fillers,Laminate inclusions,Fly ash,Nanostructure,Interface,Organo-modification,Relaxation mechanisms,Useful working range
URI: http://olympias.lib.uoi.gr/jspui/handle/123456789/29250
Appears in Collections:Διδακτορικές Διατριβές

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