Novel degradable copolyesters containing poly(ethylene oxalate) units derived from diethylene oxalate

Two series of poly(ethylene terephthalate-co-oxalate-co-sebacate) (PETOXS) have been synthesized by melt polycondensation using diethylene oxalate (DEOX) as a starting material. NMR quantified the composition, structure, and average sequence length of the copolyesters. Melting and crystallization properties differ from each other on the basis of PETOXS feature. Analysis of TG traces determined that initial degradation temperatures were affected by the content of PET. It was observed that the Young's modulus and the maximum tensile stress increased with increasing content of poly(ethylene oxalate) (PEOX) in aliphatic units, whereas the elongation at break considerably decreased. Obvious weight loss was observed in alkali hydrolysis experiments, and the degradation rates are subject to distinct factors when the ratio of two aliphatic polyester units is varied. DSC was performed to degraded copolyester samples, and the variation of melting temperature and crystallinity were investigated.