Properties modification of PET vascular prostheses

Aging mechanisms have been investigated on polyethylene terephthalate (PET) fibres extracted from various vascular prostheses in order to identify the different modifications of the material's degradation. NMR spectroscopy provides a comprehensive view of chemical structures of macromolecules. Examination of a series of PET fibres showed significant chemical differences between the virgin prostheses and the explants, especially for diethylene glycol (DEG) and cyclic oligomeric groups. These analyses revealed that PET failures in vascular prostheses are susceptible to hydrolysis during in vivo stay. We also extended this ¹H NMR technique to determine the hydroxyl and carboxyl end-group concentrations. In order to validate the ¹H NMR results, complementary techniques - chemical titration and classical viscosimetry - were used. The obtained results showed an increase in end-group concentrations and a decrease of the viscosity averaged macromolecular weight (Mv) for the explants.