Darwin P. R. Kint

A review on the potential biodegradability of poly(ethylene terephthalate)

This paper reviews the state of the art in the field of the hydrolytic degradation of poly(ethylene terephthalate) (PET) under bio-environmental conditions. Most of the papers published so far on this subject have been focused on the hydrolysis of PET at high temperatures. Although some authors claim to enhance the biodegradation properties of this aromatic polyester by copolymerization with readily hydrolysable aliphatic polyesters, no clear and satisfying conclusions can yet be formulated. Poly(ethylene terephthalate-co-lactic acid), poly(ethylene terephthalate-co-ethylene glycol), and poly(ethylene terephthalate-co-e-caprolactone) block and random copolymers are the modifications mainly investigated for biodegradable applications. The hydrodegradability and biodegradability of PET, PET copolymers and PET blends are detailed in this review. A total of 89 references including 16 patents are cited. © 1999 Society of Chemical Industry

Hydrolytic degradation of poly(ethylene terephthalate) copolymers containing nitrated units

The hydrolytic degradation at 80 °C of a series of poly(ethylene terephthalate) (PET) copolymers containing 5-nitroisophthalic (PETNI) and nitroterephthalic (PETNT) units is described. The degradation process was followed by weighting, viscometry, differential scanning calorimetry (DSC), and nuclear magnetic resonance (NMR) spectroscopy. The nitrated copolyesters degraded faster than semicrystalline and amorphous PET, and the degradation rate increased with the content of nitrated units. DSC measurements showed that the melting temperature of the semicrystalline samples increased slightly upon hydrolytic degradation, whereas the degree of crystallinity remained essentially unchanged. NMR spectroscopy revealed that hydrolysis occurred preferentially by cleavage of the ester groups of the nitrated units, and that most of the degradation products remained in the degraded polymer samples.