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Title: Preparation, characterisation, and modelling of graphene-based polymer nanocomposites with enhanced mechanical and electrical properties
Author: Santagiuliana, G.
ISNI:       0000 0004 7971 8153
Awarding Body: Queen Mary, University of London
Current Institution: Queen Mary, University of London
Date of Award: 2019
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Despite the exceptional properties of graphene and graphite nanoplatelets (GNP), the performance of their polymer nanocomposites is often disappointing. Nanofiller agglomeration is one among many other reasons for this failure in performance, but it is still poorly investigated. In this project, I have systematically studied how the mechanical and electrical properties of nanocomposites are influenced by the nanofiller's agglomeration and distribution inside the polymer matrix. I have also investigated viable routes able to take advantage of nanofiller agglomeration for the preparation of nanocomposites with enhanced multifunctionalities. A theoretical framework has been proposed to explain how a nanocomposite microstructure influences the macroscopic properties of nanocomposites. This theory well explains the loss of nanocomposite performance reported in the literature and has been further validated by experimental data obtained from model nanocomposites. These graphene- and GNP-based model nanocomposites were prepared using three different techniques. The first one, "spray-assisted layer-by-layer", followed a bottom-up approach. This method allowed tailoring the spatial distribution of graphene within the polymer matrix. Thus, the effect of nanofiller distribution on the nanocomposite electrical properties was determined. The second technique was an alternative top-down approach inspired by the preparation of puff pastry for croissants and called "pressing-and-folding" (P&F). This iterative technique was developed to prepare samples containing well-defined, increased dispersion/distribution levels of nanofiller. Consequently, it was possible to study how the nanocomposite mechanical properties improve with nanofiller dispersion, and to demonstrate how the electrical conductivity can reach a maximum value for non-perfect nanofiller dispersion/distribution states. Thirdly, nanocomposites prepared by traditional melt-blending techniques (twin-screw extrusion and multi-layer coextrusion) were used to compare and assess the properties of P&F nanocomposites and highlight the differences between P&F and melt-blending techniques. Finally, these theoretical and experimental findings illustrate how tailoring the microstructures could enhance desired technological functionalities of nanocomposites, such as mechanical reinforcement, health-monitoring, self-heating, and energy management.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available