Abstract: In this study, blended film of poly(lactic acid) (PLA)/poly(butylene adipateco terephthalate) (PBAT) was prepared by a twinscrew extruder and a single screw extruder. The thermal, mechanical properties and microstructure had been investigated. The biodegradation rate of the blends under composting condition was measured, and the structure, element content, and thermomechanical behavior before and after degradation was characterized. It indicated that PLA/PBAT blend was an immiscible system, and the addition of PBAT improved the flexibility of PLA. It also found that, the biodegradation rate of neat PLA was greater than that of neat PBAT, and the biodegradation rate of PLA/PBAT blends was decreased with increasing PBAT content. Furthermore, the degradation products may accelerate the hydrolysis of PBAT at the beginning of degradation. At the earlier stage of degradation under composting condition, the long polymer chains of PLA, PBAT and their blends hydrolyzed to short chains without chemical structure change of the monomers. The degradation of neat PLA and PBAT initially occurred at amorphous phase, however the degradation of PLA/PBAT blends occurred at both amorphous and crystalline phases simultaneously. Moreover, the degradation of PLA chains in amorphous phase in blends was decreased affected by the addition of PBAT. The degradation of PLA/PBAT blends was mainly started with a hydrolysis.

Key words: poly(lactic acid), poly(butylene adipate-co-terephthalate), biodegradation rate