Abstract:
With the increasing pollution of marine plastic, the degradation properties of biodegradable plastic in seawater have attracted much attention and controversy. Four typical biodegradable polyesters polylactide (PLA), poly(butylene adipate-
co-terephthalate) (PBAT), polybutylene succinate (PBS) and poly(
ε-caprolactone) (PCL), were selected. The degradability of these materials in seawater was studied by investigation of the change of their mass loss, molecular weight, mechanical properties, and spline morphology after being immersed in natural seawater for 364 d. Further, the effects of environmental factors on the degradation properties of four polyesters were studied in natural water, static seawater, static river water, distilled water, sterilized seawater, and lab-prepared seawater. Results show that the degradability of biodegradable polyester in natural seawater is significantly lower than that in compost. The most market-demand PLA almost exhibits no degradation after 364 d. The mass losses of PBAT and PBS are no more than 3% after 364 d. PCL degradation is the fastest and the mass loss of PCL degradation is 32%. Microorganisms seem to be the key factors affecting the rate of biodegradation. It is also found that the high concentration of inorganic salt has a promotion to the non-enzymatic hydrolysis process.