RADIATION-INDUCED CROSSLINKING AND PLASTICIZATION EFFECTS ON BIODEGRADATION OF POLY (L-LACTIC ACID)

TRAN MINH QUYNH1, TRAN BANG DIEP1, NGUYEN VAN BINH1, HOANG PHUONG THAO1, PHAM QUANG HIEU1, LE QUANG LUAN1
1 Hanoi Irradiation Center, VINATOM Km 12, Street 32, Minh Khai, Tu Liem, Hanoi

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Abstract

Different plasticized poly (L-lactic acid) (PLLA) films containing low molecular weight polyethylene glycol (PEG 1000), with or without addition of triallyl isocyanurate (TAIC) were prepared by hot-press method. The crosslinking structures were induced in the plasticized films by gamma irradiation with radiation doses ranging from 10 to 100 kGy using Cobalt-60 source at Hanoi Irradiation Center. The influences of plasticizer amount and radiation dose, namely crosslinking density on enzymatic degradation of the film were investigated in the presence of proteinase K. The results revealed that all PLLA samples were significantly degraded by immerging in a Tris/HCl buffer solution containing proteinase K. At the same period of incubation, the weight of PLLA increased by plasticization and radiation treatment, but much reduced by radiation-induced crosslinking. Biodegradability of the PLLA was also investigated by buring the films in soil and compost at different temperature. SEM images of the degraded films revealed that microbial degradation of PLLA occurred not only on the surface but also in the polymer bulk. The microbial degradation rate of PLLA at 50°C was higher than that at room temperature, meaning that most of the PLLA-degrading microorganisms probably belong to the thermophile.

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References

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