Trichloroacetyl isocyanate reacts rapidly and quantitatively with both acid and hydroxyl chain ends to form derivatives that can be readily determined by (1)H-NMR spectroscopy. This method provides a convenient mean for characterization of polyethylene terephthalate (PET) end-groups. The (1)H-NMR spectroscopy has been applied to describe the chemical aging of the PET vascular prostheses by determination of the hydroxyl and carboxyl end-group concentrations and therefore the macromolecular weight. To validate (1)H-NMR results, we used chemical titration of the end-groups and classical viscosimetric method as complementary techniques. The analyses made on the explants of different lifetime demonstrated a significant deterioration compared with the virgin prostheses. A high degradation of macromolecular weight is observed. This phenomenon is explained by a random scission of the ester linkages.
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