A NEW APPROACH OF CHARACTERIZING THE HYDROLYTIC DEGRADATION OF POLY(ETHYLENE-TEREPHTHALATE) BY MALDI-MS

The hydrolytic degradation of technical poly( ethylene terephthalate) (PET) was investigated by means of different methods such as size-excl usion chromatography (SEC), viscometry, light-scattering, thin-layer c hromatography, end-group titration, and matrix-assisted laser desorpti on/ionization mass spectrometry (MALDI-MS). The long-term degradation was simulated by exposing PET filament yarns to aqueous neutral condit ions at 90 degrees C for up to 18 weeks. By means of MALDI-MS and thin -layer chromatography, the formation of different oligomers was obtain ed during polymer degradation. As expected, an ester scission process was found generating acid terminated oligomers (H-[GT](m)-OH) and T-[G T](m)-OH and ethylene glycol terminated oligomers (H-[GT](m)-G), where G is an ethylene glycol unit and T is a terephthalic acid unit. Addit ionally, the scission of the ester bonds during the chemical treatment led to a strong decrease in the number of cyclic oligomers ([GT](m)). The occurrence of di-acid terminated species demonstrated a high degr ee of degradation. (C) 1997 John Wiley & Sons, Inc.