Biodegradation in seawater of aliphatic polyesters

In order to utilize biodegradable polymers as a functional material, it is important to make the best use of their biodegradability. Biodegradation of aliphatic polyesters, such as PCL, PBSA and P3HB, in seawater was investigated. BOD test using seawater and field test were carried out. As for BOD test, several factors were investigated such as tide, preservation of seawater, sampling place, population of microorganism, and seawater temperature. Biosynthesized P3HB and PHBHH showed rapid biodegradation by BOD method. As for synthetic polyesters, PCL also degraded fast. However, PBSA which is a popular biodegradable polymer in soil was not always biodegraded by BOD method with seawater. PBS and PBAT showed much slow biodegradation. Solvent cast films were immersed in the sea at a depth of 1.5 m. After 4 weeks, the weight loss of P3HB film was about 90%. On the contrary, the biodegradation by BOD method for 4 weeks was around 50%. Synthetic polyesters also showed obvious weight loss in field test, in contrast to the BOD results.