student profile: Mr Aaron Loy


Thesis work

Thesis title: The Synthesis and Characterization of Bioglasses, Bioglass-Ceramics and Glass-Ionomer Cements from Recycling Waste for Bone and Dental Restoration

Supervisors: Chris LING , Siegbert SCHMID

Thesis abstract:

This PhD thesis presented the research work on synthesis and materials characterisation of SiO2–Al2O3–P2O5–Na2O–CaO–CaF2-based fluoroaluminosilicate glasses, fluorapatite glass-ceramics and dental glass-ionomer cements (GIC) for bone and dental restoration. They are made from recycling waste. In general, the thesis consists of four major parts which focused on different categories of materials.
The first part of the thesis focused on the crystallographic, chemical and thermal characterisation waste materials such as rice husk ash, aluminium cans, oyster shells and soda-lime-silicate glass bottles. Specifically, the characterization of pseudoboehmite, dawsonite and several polymorphs of alumina that are synthesised from the recycling of disposable aluminium cans. CO2-sequestration and thermal treatment methods were employed to the synthesis process. The effect of thermal treatment on their chemical and structural transformation were examined by PXRD, FTIR, TGA, SEM and SANS techniques.
The second part of the thesis includes the synthesis and structural characterization of fluoroaluminosilicate glasses. The fluoroaluminosilicate glasses were prepared by water-quenching of molten glass at 1450 °C to room temperature. The chemical composition of the glasses were varied to investigate their effect on their microstructure. The glass powder was characterized by SANS, USANS and SAXS techniques. The results provide microstructural information of the glass particles at wide range size (1 nm to 10 µm).
The third part involves the crystallization of the fluoroaluminosilicate glasses by thermal treatment at different temperatures. These fluorapatite glass-ceramics consist of fluorapatite, mullite, anorthite or/and albite crystal phases dispersed in glass matrix. The crystallization of the glass-ceramics was studied by PXRD, FTIR, simultaneous TGA/DSC analysis and SANS.
The last part aimed to study the chemical and structural change of GIC pastes during setting reaction. GIC pastes were formulated by the mixture of glass, polyacrylic and water. The formation of polyacrylate and hydrogel phases in GIC paste was identified by the FTIR. The structural evolution of each phases in the GIC paste was investigated by the SANS, USANS with the aid of D2O/H2O contrast variation method.

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