Graphene nanocomposites have been successfully prepared in this study in the form of a sandwich structure of PMMA/graphene/SU-8. It has been proved that Raman spectroscopy is a powerful technique in the characterisation of the structure and deformation of graphene. The 2D band of the monolayer graphene has been used in the investigation of stress transfer in the graphene reinforced nanocomposites. It has been demonstrated that the 2D band moves towards low frequency linearly under tensile stress, which is shown to be significant method of monitoring the strain in graphene in a deformed specimen. The Raman spectroscopy behaviour under deformation validates that the monolayer graphene acts as a reinforcing role in nanocomposites although it is only one atom thick.A systematic investigation of the deformation of bilayer, trilayer and few-layer graphene has been undertaken with a view to determine the optimum number of layers for the reinforcement of nanocomposites. It has been demonstrated that monolayer graphene is not necessarily the optimum material to use for reinforcement in graphene-based polymer nanocomposites and bilayer graphene will be equally as good as monolayer graphene. There is therefore a balance to be struck in the design of graphene-based nanocomposites between the ability to achieve higher loadings of reinforcement and the reduction in effective Young’s modulus of the reinforcement, as the number of layers in the graphene is increased.Both the G and 2D bands have been found to undergo splitting under high strain levels or asymmetric band broadening in lower strain deformation. The G band polarisation property has been utilized to determine the crystallographic orientation of monolayer graphene by measuring the intensity ratio of G-/G+ bands. Analogously, the 2D band also undergoes strain-induced splitting where the 2D- band has higher Raman shift rate than that of the 2D+ band.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:570289 |
| Date | January 2013 |
| Creators | Gong, Lei |
| Contributors | Young, Robert; Kinloch, Ian |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://www.research.manchester.ac.uk/portal/en/theses/deformation-micromechanics-of-graphene-nanocomposites(b4e4780d-738f-4629-9dbb-151b1230bd52).html |
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