Lama, Giuseppe Cesare (2017) Shape Memory Polymers Charged with Modified Carbon-Based Nanoparticles. [Tesi di dottorato]

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Item Type: Tesi di dottorato
Lingua: English
Title: Shape Memory Polymers Charged with Modified Carbon-Based Nanoparticles
Creators:
CreatorsEmail
Lama, Giuseppe Cesaregiuseppecesare.lama@unina.it
Date: 10 April 2017
Number of Pages: 181
Institution: Università degli Studi di Napoli Federico II
Department: Ingegneria Chimica, dei Materiali e della Produzione Industriale
Dottorato: Ingegneria dei prodotti e dei processi industriali
Ciclo di dottorato: 29
Coordinatore del Corso di dottorato:
nomeemail
Mensitieri, Giuseppegiuseppe.mensitieri@unina.it
Tutor:
nomeemail
Ambrogi, VeronicaUNSPECIFIED
Cerruti, PierfrancescoUNSPECIFIED
Date: 10 April 2017
Number of Pages: 181
Uncontrolled Keywords: MWCNT, Graphene Oxide, Shape Memory
Settori scientifico-disciplinari del MIUR: Area 03 - Scienze chimiche > CHIM/07 - Fondamenti chimici delle tecnologie
Area 09 - Ingegneria industriale e dell'informazione > ING-IND/22 - Scienza e tecnologia dei materiali
Date Deposited: 25 Apr 2017 18:05
Last Modified: 08 Mar 2018 13:50
URI: http://www.fedoa.unina.it/id/eprint/11821
DOI: 10.6093/UNINA/FEDOA/11821

Abstract

In this thesis, shape memory nanocomposites were prepared and characterized. The polymer matrix consisted in an epoxy-based liquid crystalline elastomer (LCE). Multi-walled carbon nanotubes (MWCNT) and graphite nanoplatelets (GNP) were selected as fillers. The influence of different contents of nanofillers on mechanical, thermal and shape memory properties was evaluated. In order to disperse and homogeneously distribute the nanofillers within the polymer matrix an in-depth evaluation on the optimal conditions to synthesize the materials was carried out. These conditions had a substantial influence on the final distribution of the nanofillers within the epoxy-based matrix, which was analyzed from a macroscopic and microscopic point of view. The best results were obtained through a chemical surface modification of the nanoparticles. The chemical modification of MWCNTs consisted in grafting the selected epoxy monomers on the surface. The obtained adducts were characterized in terms of chemical, thermal and morphological features. Concerning GNP, a similar protocol based on surface modification was carried out. In this case, a preliminary oxidation process was performed in order to promote the exfoliation of graphene sheets, in form of graphene oxide (GO), and to favour their dispersion within the polymer matrix. Different degrees of oxidation were attempted. GO nanoparticles were successively modified with epoxy monomers. Also in this case, chemical, morphological, structural and thermal characterization was carried out. Surface modified carbonaceous nanoparticles were then dispersed in varying amounts in the organic matrix. The obtained nanocomposite systems were characterized in their chemical-physical and morphological properties. The adopted compatibilization strategies used for both MWCNTs and GNP were found to be extremely effective to get homogeneous samples and to enable a dramatic enhancement of the actuation extent at low nanofiller content. Moreover, the stress threshold required to trigger the reversible thermomechanical actuation was significantly decreased. The effect of nanoparticles on thermomechanical properties of the materials was correlated to the microstructure and the phase behavior of the host system. Results demonstrated that the incorporation of carbon nanofillers amplified the soft-elastic response of the liquid crystalline phase to external stimuli. Tunable thermomechanical properties of these systems make them suitable for a variety of potential advanced applications ranging to robotics, sensing and actuation, and artificial muscles.

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