Study on oxidative degradation behaviors of polyesterurethane network

In this study H₂O₂/CoCl₂ system was used as an oxidative environment to investigate the in vitro degradation behavior of a crosslinked polyesterurethane network. Weight loss, water absorption, mechanical properties, swelling degree and gel content were determined as a function of degradation time. The results showed that the H₂O₂/CoCl₂ system could effectively accelerate the degradation of the polyurethanes. The samples had almost completely degraded after 84 days of incubation in a 3% H₂O₂/2% CoCl₂ solution at 37 °C. The weight loss process could be approximately divided into three major phases: the weight decreased slowly during an induction phase (1), which was followed by a phase characterized by accelerated weight loss (2), and finally by a phase showing slow linear weight loss until complete erosion (3). The attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectra of degraded polyurethane networks showed that the polyurethane underwent chain scission of the copolyester segment chains, and the joints of copolyester and 2,2,4- and 2,4,4-trimethylhexamethylene during degradation in the oxidative environment. The glass transition temperature of degraded polyesterurethane networks decreased significantly with increasing degradation time. From these results the H₂O₂/CoCl₂ system can be used as an oxidative condition to evaluate the in vitro degradability of polyesterurethane.