Poly(butylene succinate)-based prepolymers containing itaconic acid units or maleic acid units in the main chain were synthesized through the condensation reaction of 1,4-butanediol, succinic acid, and itaconic acid or maleic acid. The resulting prepolymers, with weight-average molecular weights in the several thousands, were cured at 115degreesC with benzoyl peroxide to produce crosslinked polyesters that were insoluble in chloroform. Differential scanning calorimetry analysis revealed that the glass-transition temperature rose with crosslinking and that the melting temperature and heat of melting decreased with crosslinking . These results implied that crosslinking was successfully carried out and that the crystallinity of the polymer decreased. The crosslinked polymer showed lower biodegradability in the biochemical oxygen demand assay with activated sludge but retained some biodegradability. (C) 2005 Wiley Periodicals, Inc.