| STUDY |
Each of the respective copolymers, regardless of the specific TA:SA ratio concentration, were compression molded into thin slabs in the manner described previously in Examples I and II. The erosion rates for each copolymer was then evaluated by placing the copolymer matrix in phosphate buffered solutions at 37.degree. C. The test conditions and duration were identical to those described in Example I and Figs. 1 and 2. The results indicated that the rate of erosion was inversely proportional to the concentration of TA; accordingly, the greater the TA:SA ratio, the less the rate of erosion for the matrix. It will be appreciated that the two monomers TA and SA thus present the two extremes of hydrophobicity; while SA hydrolytically degrades in atmospheric moisture, TA always remains highly resistant to hydrolysis regardless of specific conditions. By varying the concentration ratio or TA to SA in the copolymer, a matrix having a range of different degradation rates is thus obtained without regard to the degree of polymerization and without regard to the total molecular weight of either prepolymer or the copolymer itself. Additionally, by altering the TA:SA ratio concentration, the elastic properties of the matrix regardless of configuration or geometric dimensions can be altered to suit the users' needs or desires from a rigid matrix to a rubbery flexible matrix.
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