A new biodegradable copolyester poly(butylene succinate-co-ethylene succinate-co-ethylene terephthalate) Original Research Article

To obtain a biodegradable polymer material with satisfactory thermal properties, higher elongation and modulus of elasticity, a new copolyester, poly(butylene succinate-co-ethylene succinate-co-ethylene terephthalate) (PBEST), was synthesized via direct polycondensation from three prepolymers of butylenes succinate, ethylene succinate and ethylene terephthalate (ET). The resulting copolyesters, PBEST, were characterized by 1H-NMR, DSC, TG and WAXRD, and their melting temperature (Tm), melting heat of fusion (ΔHm), glass-transition temperature (Tg), and thermal decomposition temperature (Td) (1.5 wt%) were obtained. Compared to poly(butylene succinate-co-ethylene succinate) (PBES), PBEST has improved thermal properties such as higher Tm and Td due to the incorporation of poly(ethylene terephthalate) unit into the main chains of copolyesters, but very low crystallization speeds. The degradation test of copolyesters in a compost condition shows that the degradability of PBEST is as a function of content of ET.