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Title: Manufacture and characterisation of novel resorbable phosphate based glass fibres for biomedical applications
Author: Shaharuddin, Sharifah Imihezri bt. Syed
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2012
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Abstract:
This thesis presents a systematic characterisation of relatively simple to increasingly complex phosphate based glass (PBG) systems. Resorbable PBG can potentially be applied as fibrous reinforcement for resorbable polymers such as polY(Ecaprolactone) for biomedical applications. These resorbable composites are of considerable interest since subsequent absorption allows for a gradual transfer of load to the healing bone and avoids the need for secondary surgery. The PBG compositions investigated ranged from binary, ternary to quaternary and quinternary glass systems. The effects of these compositions on their thermal and structural properties were investigated. The studies revealed that the thermal properties such as glass transition and thermal stability (defined as the difference between glass transition and the onset of crystallisation) improved with increasing phosphate content as well as with the incorporation of additional higher valence cations such Ca2+, Fe2+/3+ and Ti3+/4+. It was observed that the addition of Fe2+/ 3+ and Ti3+/4+ had a more profound effect on the thermal properties in comparison to increasing phosphate content. Also of primary interest was investigation into the viscosity properties for these glasses. These studies enabled an alternative route for fibre drawing of PBG which was via the preform drawn method. The viscous properties of these glasses were compared in terms of their fragility index for a viscosity region of log · 1 08 - log 105 .5 Pa s. The quaternary and quinternary compositions investigated were successfully drawn into fibres via the preform drawn method and the measured fragility index was in the range of36.6 to 44.1. It was found that fibres could be drawn witl}in ±10°C of the estimated fibre drawing temperature. In brief, a high fragility index reflected a 'fragile' melt whereas low fragility indexes indicated a 'strong' melt. It is desirable to have a 'strong' melt since it will make the fibre drawing temperature less critical provided that crystallization can be avoided. The fiberisation process (via the preform method) also highlighted the importance of identifying a suitable etching procedure as some of the preforms had undergone surface hydrolysis reaction which made fibre drawing extremely difficult for those specific formulations. The most iii exciting, novel and challenging studies were designing novel hybrid (core/clad) glass preforms and fibres. The idea was to explore the possibility of creating PBG glass fibres with specific ion release profiles via alternate formulations for the both core and clad. The successful co-extrusion and fiberisation of quarternary and quinternary glass systems provided the required proof of concept. The dissolution properties of both bulk glass and fibres were also examined. It was found that Ti containing glasses were more effective in reducing the solubility rate compared to Fe ions. An interesting phenomenon was observed during the dissolution of annealed and non-annealed fibres. It was found that the strength of the annealed glass fibres increased significantly with dissolution time compared to nonannealed fibres. This was attributed to a combination of higher density as well as the peeling away of outer layers from the fibre surfaces. A similar trend was also observed for the Fe clad hybrid glass fibre. The nonexistent peeling effect of the hydrated layer for Ti clad hybrid glass fibres indicated that the Ti fibres were more durable in comparison to the Fe clad hybrid glass fibres. Overall, this work has improved the understanding on the correlation between the thermal properties especially viscosity of phosphate based glasses and fiberisation process via the preform drawn method. iv
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.605587  DOI: Not available
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