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Title: The processing and performance of thermoplastics for use in medical device applications
Author: Ruddy, Aine Catherine
ISNI:       0000 0001 3539 3308
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2008
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The polymer medical device market is expanding rapidly, particular in the use of catheters and the manufacturer faces various challenges associated with the production of these devices including: resin selection, melt processing, addition ofradiopaque agents and surface finish. . Thermoplastic polyurethanes (TPUs) are widely used in the medical device industry due to their biocompatibility and unique mechanical performance, which can be attributed to the multi-block structure comprising of hard and soft segments. This programme of work begins by selecting a wide range of commercially available TPUs and the results showed marked differences in processability, mechanical an~ thermal performance due to differences in molecular weight, ratio of hard and soft segments and phase mixing. This thesis also offers an investigation into the effect of radiopaque fillers on the processability and performance of TPUs and PVCs and highlights the difficulty associated with this. The results showed addition of radiopaque fillers decreased the viscosity of these resins due to hydrophobic degradation, wall slip and thermal history effects. Nylon has been traditionally used in catheter balloon manufacture due to the excellent tensile performance, however, these polyamides lack the flexibility required for medical device applications. In this work nylon/Pebax blends were formulated and the results showed that addition of Pebax resulted in better processability and improved mechanical performance. In the latter stage of this work a range of tubes were extruded from various resins and blends used throughout the program of work and the mechanical performance including torqueability, manoeuvrability, flexibility and trackability of each tube were modelled. The results enabled the recommendations of the' materials for various medical device applications ranging from coronary angioplasty to urinary drainage. The final section ofthe thesis investigated the effect of Atmospheric Pressure Glow Discharge (APGD) treatment on the contact angle and surface functionality of the TPUs. The results showed that optimum discharge parameters are required for improved surface performance and these are related to creation ofoxygen functional groups on the surface.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available