The hydrolytic degradation of bioabsorbable polydioxanone (PPDX) was studie
d in a phosphate buffer solution, pH = 7.4, 37 degrees C. The degradation w
as evaluated by analyzing the changes in the elastic modulus and morphologi
cal changes. After 10 weeks, the weight loss, pH and molecular weight chang
es suggested diffusion of low molecular weight chain segments into the reac
tion medium as a consequence of the breaking of ester bonds in the material
. The crystallinity (X-c) increased with hydrolysis time, indicating the fi
rst step of the degradation process. Modulus was found to decrease, indicat
ing that chain scission proceeded in two steps: the first occurring in the
amorphous regions of microfibrils and intermicrofibrillar space; the second
in the crystalline regions, resulting in a lower stress value for the chai
n segments when submitted to external forces. Surface morphological changes
suggest a heterogeneous degradation mechanism by layers. (C) 2000 Elsevier
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