| The primary aim of this study was to develop a mathematical model and experimental approach that would yield the diffusivity of a polymer system in various flow profiles. This thesis presents a preliminary assessment of blending poly-L-lactic acid (PLLA) and poly-&epsis;-caprolactone (PCL) to yield a novel polymer system that might find uses in various medical applications. One such application is tissue engineering. Inspired by previous works done on the study of cell seeding [33, 34], the author proposes measuring the degradation and diffusivity characteristics of a PLLA/PCL composite in a controlled fluid environment, where fluid rotates in a well-characterized fashion. Blending of PLLA and PCL was done by solvent casting, using a polymer/solvent ratio of 2% (by weight/volume). The composite was placed and tested in a custom-made annulus (Taylor-Couette cylinder) filled with de-ionized water at 25°C. A mathematical model was formulated, based on this particular Taylor-Couette device, to describe the kinetics of PLLA/PCL degradation from the onset of its bulk erosion. The concentration of the polymer blend was determined as a function of radial (r) and tangential (&thetas;) distance, and time (t). The concentration equation can be used to yield the diffusivity value for the blend once its initial and final molar concentrations are known. An application of this model includes the calculation of diffusivity of any polymer system placed in this device. The theoretical assessment of degradation may, in the future, help researchers tailor the properties, e.g., mechanical properties, biocompatibility, and biodegradability, of polymer blends so that they become more suitable for use in drug delivery or other medical applications. |
