Journal of Polymers and the Environment

, Volume 14, Issue 3, pp 239–248 | Cite as

Enzymatic Degradation of Poly(l-Lactic Acid): Effects of UV Irradiation

  • Hideto TsujiEmail author
  • Yoshihisa Echizen
  • Yoshiro Nishimura
Original Paper


Amorphous and crystallized poly(l-lactic acid) (PLLA-A and PLLA-C, respectively) films were prepared, and the proteinase K-catalyzed enzymatic degradation of UV-irradiated and non-irradiated PLLA-A and PLLA-C films was investigated for periods up to 10 h (PLLA-A) and 60 h (PLLA-C). The molecular weights of both the PLLA-A and PLLA-C films can be manipulated by altering the UV irradiation time. The enzymatic weight loss values of the UV-irradiated PLLA films were higher than or similar to those of the non-irradiated PLLA film, when compared with the specimens of same crystallinities. UV irradiation is expected to cause the PLLA films to undergo chain cleavage (a decrease in molecular weight) and the formation of C=C double bonds. It seems that the acceleration effects from decreased molecular weight on enzymatic degradation were higher than or balanced with the disturbance effects caused by the formation of C=C double bonds. After enzymatic degradation, a fibrous structure appeared on the spherulites of the UV-irradiated PLLA-C film. This structure may have arisen from chains containing or neighboring on the C=C double bonds, which were enzymatically undegraded and assembled on the film surface during enzymatic degradation. The results of this study strongly suggest that UV irradiation will significantly affect the biodegradation behavior of PLLA materials in the environment.


Poly(l-lactic acid) Poly(l-lactide) Enzymatic degradation UV irradiation Biodegradable polyesters 



The authors thank Ms. Mikiko Fujita, Textile Research Center, Aichi Industrial Technology Institute (AITEC) for the irradiation experiments. This research was supported by a Grant-in-Aid for Scientific Research on Priority Area, “Sustainable Biodegradable Plastics”, No. 11217209, and The 21st Century Centers of Excellence (COE) Program, “Ecological Engineering for Homeostatic Human Activities”, from the Ministry of Education, Culture, Sports, Science and Technology (Japan).


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Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  • Hideto Tsuji
    • 1
    Email author
  • Yoshihisa Echizen
    • 1
  • Yoshiro Nishimura
    • 2
  1. 1.Faculty of Engineering, Department of Ecological EngineeringToyohashi University of TechnologyTempaku-cho, ToyohashiJapan
  2. 2.Mikawa Textile Research Center, Aichi Industrial Technology Institute (AITEC)Aichi Prefectural GovernmentOtsuka-cho, GamagoriJapan

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