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Title: Physicochemical characterisation of bioactive biodegradable polymers prepared using hot melt extrusion.
Author: Douglas, Mary Joan Paula.
ISNI:       0000 0001 3430 5361
Awarding Body: Queen's University of Belfast
Current Institution: Queen's University Belfast
Date of Award: 2008
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This work set out to characterise the extent to which the model antibacterial drug Nalidixic Acid (NA) affected the biodegradable polymer Polycaprolactone in terms of its' mechanical, thermal, and morphological properties alongside any changes in topography and by creating a monolithic dispersion for drug release. Also considered were the additional effects that a Polyethylene Glycol pore former and copolymer Poly l-lactide had on the Polycaprolactone and the Nalidixic Acid release profile. Overall it appeared that the addition of the NA caused the mechanical modulus to improve, producing increased stiffhess and less ductility in the blends. However, this stiffening led to attenuated strength and elongation. In terms ofthe thermal properties, a nucleating effect due to NA was noted alongside a decrease in crystallisation kinetics which led to the changes in mechanical properties. It was found that the Nalidixic Acid and Poly l-lactide acted as a filler material within the Polycaprolactone matrix, increasing the viscosity of the blends, which would influence subsequent processing temperatures and shear rates. The opposite effect was observed with the use of the Polyethylene Glycol, whereby, due to its low molecular weight it acted as a lubricating agent, thus decreasing the viscosity. The variations in the mechanical, thermal and morphological properties of the blends were ascribed to the immiscibility of the Polycaprolactone with the other materials, each existing as separate phases within the blends. The Nalidixic Acid release profiles indicate that rapid device exhaustion times and higher extent ofdrug release was observed when the blends were prepared by twin screw extrusion (to increase dispersion) and crash cooled (to increase Nalidixic Acid solubility). Overall no detrimental effects were noted on the Polycaprolactone matrix when used as a drug delivery vehicle for Nalidixic Acid, with the bulk Polycaprolactone remaining relatively unchanged.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available