Mechanical properties and thermal stability of poly (L-lactic acid) treated by Co-60 gamma radiation

Tran Minh Quynh1, Nguyen Van Binh1, Pham Duy Duong1, Hoang Phuong Thao1, Pham Ngoc Lan2, Le Thi Mai Linh2
1 Hanoi Irradiation Center, Vietnam Atomic Energy Institute, No.5, Minh Khai, Tu Liem, Hanoi
2 Hanoi University of Science, Vietnam National University, Nguyen Trai, Thanh Xuan, Hanoi

Main Article Content

Abstract

Poly (L-lactic acid) (PLLA) was mixed with 5 wt% polyethylene glycol 1000 g.mol-1 (PEG) as a plasticizer and 3 wt% triallyl isocyanurate (TAIC) as a crosslinking agent for preparation of the plasticized PLLA films. The crosslinking plasticized materials were prepared from the plasticized PLLA by irradiation with various radiation doses under the Cobalt-60 gamma radiation source at Hanoi Irradiation Center. The crosslinking structures were introduced in different formulations of PLLA, and the crosslinking density increased with radiation dose and seemed to be saturated at 50 kGy. The resulting stable crosslinking network inhibited the mobility for crystallization of PLLA chains. As a result, thermal stability of the crosslinking plasticized PLLA increased, and the plasticized PLLA crosslinked with TAIC at 50 kGy become much higher than that of initial PLLA with a very small endothermic peak at its melting temperature in the DSC thermogram. The stress-strain curves of the crosslinking plasticized PLLA showed the toughness of the materials reduced but still higher than that of initial PLLA, whereas its tensile strength was much improved by radiation crosslinking.

Article Details

References

[1] Stevens ES In Green plastics: an introduction to the new science of biodegradable plastics. Princeton University Press. 2002.
[2] Drumright RE, Gruber PR, Henton DE. Adv Mater 2000, 12(23):1841-1846.
[3] Quynh TM, Mitomo H, Nagasawa N, Wada Y, Yoshii F, Tamada M. Properties of crosslinked polylactides (PLLA & PDLA) by radiation and its biodegradability. Eur Polym J, 2007, 43(5): 1779-1785.
[4] Garlotta D. J. Polym Environ 2001, 9(2): 63-84.
[5] Jin F, Hyon SH, Iwata H, Tsutsumi S. Macromol. Rapid Commun 2002, 23:909-12.
[6] Chapiro A. In Radiation Chemistry of Polymeric System. Jhon Wiley & Sons, New York. 1961. p.1.
[7] Nikitina TS, Zhuravskaya V, Kuzminsky AS. In Effects of Ionizing Radiation on High Polymers. Gordon and Breach Inc, New York. 1963.
[8] Olejniczak J, Rosiak J, Charlesby A. Rad Phys Chem 1991, 38:113-118.
[9] RJ Woods, AK. Pikaev. Applied Radiation chemistry: Radiation processing. John Wiley & Sons. NewYork 1994, pp. 343-357.
[10] Mitomo H, Kaneda A, Quynh TM, Nagasawa N, Yoshii F. Polymer 2005, 46:4695-03.
[11] Kulinski Z, Piorkowska E, Gadzinowska K, Stasiak M. Plasticization of poly (L-lactide) with poly (propylene glycol). Biomacromolecules 2006, 7(7): 2128-2135.
[12] Quynh TM, Diep TB, Mohammed IS, Kamaruddin BH. Improvement of thermal stability of the plasticized poly (L-lactic acid) PLLA by radiation crosslinking. Nuclear Science and Technology 2012; 6: 1.