Browsing by Author "Alghamdi, Abdullah Ahmed A"

Now showing 1 - 1 of 1

Restricted
Structure-Property Relationships in Reduced Graphene Oxide Networks and Composites
(Saudi Digital Library, 2023-10-27) Alghamdi, Abdullah Ahmed A; Dalton, Alan
This thesis investigates the influence of sonication time on the structure, properties, and supercapacitor performance of graphene oxide (GO) films, as well as the impact of graphene oxide on the properties of natural rubber composites. The study begins by examining the effects of sonication treatment on GO dispersions and films, analysing the chemical structure for the presence of oxygen-containing functional groups in GO, and demonstrating that post-dilution sonication improves dispersion stability. Spectroscopic and microscopy analyses reveal changes in the optical, structural, and electronic properties of GO dispersions due to sonication, resulting in smaller sheet sizes and improved exfoliation. Mechanical testing shows reduced tensile strength and toughness in sonicated GO films, while spray deposition enhances the electrical conductivity of thermally reduced GO films. Next, the thesis explores the electrochemical reduction process of GO and investigates the capacitive behaviour of the electrodes. Through various analyses, including capacitance as a function of scan rate, time constant relationship, and capacitive and diffusive contributions using a Dunn’s model, it is found that longer sonication times lead to increased capacitance values. Morphological analysis reveals smaller sheet sizes and overlapping sheets in sonicated samples. The study demonstrates that sonication prior to reduction enhances the capacitance of the reduced graphene oxide (rGO) material by increasing specific surface area and reducing equivalent resistance. Finally, the thesis investigates the structural, mechanical, and thermomechanical properties of reduced graphene oxide-natural rubber (rGO-NR) composites. The curing process shows a colour change phenomenon, indicating a cooperative reduction-curing process. Microscopy analysis confirms the presence of a conductive network, and mechanical tests reveal improved load-carrying capacity, stiffness, and resistance to deformation with the incorporation of GO. Thermomechanical analysis demonstrates increased rigidity and reversible deformation with temperature variations. Overall, this thesis contributes to a better understanding of the structural and charge storage mechanisms of GO-based materials, as well as the mechanical and thermomechanical characteristics of rGO-NR composites. These findings emphasise the importance of optimising GO-based materials for electrochemical applications across diverse industrial sectors.
10 0