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Title: Plastic UV radiation protection operating by Stokes emission
Author: Li, Rui
Awarding Body: Brunel University London
Current Institution: Brunel University
Date of Award: 2013
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A range of inorganic nanoparticles/nanophosphors that act as ultraviolet radiation absorbers were characterised and assessed in this thesis. Iron doped lithium aluminate phosphor was synthesised using a solid state reaction and also by flame spray pyrolysis. The phosphors prepared by different synthesis methods were characterised to identify their crystal structures and morphologies. Downconverting photoluminescent properties of the phosphors both as pure powders and embedded in polypropylene by co-rotating twin screw extrusion are reported. Zinc oxide nanoparticles made by flame spray pyrolysis were also investigated. They were incorporated into polymers by means of three different approaches including co-rotating twin screw extrusion, spin coating and solvent casting. The resulted composite films were explored to understand the distribution of the zinc oxide nanoparticles. The transmittance and ultraviolet absorption of the nanocomposites were studied and are reported herein. Another set of nanophosphors studied were zinc rich luminescent zinc oxides. They were prepared from the zinc oxide nanoparticles by firing them in a reducing atmosphere. The as-prepared nanophosphors manifested good downconverting photoluminescent properties and maintained their functions when embedded into polystyrene by solvent casting. In this thesis a new route of synthesising aluminium doped zinc oxide nanoparticles was also established. This new approach was based on a series of unexpected results within some trials that were attempting to coat a layer of alumina on the zinc oxide nanoparticles. The concentration of the Al3+ in the final product could be adjusted by tailoring the amount of the Al3+ in the reactants during the synthesis procedures. It was also possible to coat various zinc oxide nanostructures with the aluminium doped zinc oxide.
Supervisor: Silver, J. Sponsor: EPSRC ; TSB
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Nanoparticles/ nanophosphors ; polymer nanocomposites ; LiAlO2:Fe ; ZnO