Degradation of poly(lactide-co-glycolide) (PLGA) and poly(L-lactide) (PLLA) by electron beam radiation.
This paper seeks to examine the effects of electron beam (e-beam) radiation on biodegradable polymers (PLGA and PLLA), and to understand their radiation-induced degradation mechanisms. PLGA (80:20) and PLLA polymer films were e-beam irradiated at doses from 2.5 to 50 Mrad and the degradation of these films were studied by measuring the changes in their molecular weights, FTIR spectra, thermal and morphological properties. The dominant effect of e-beam irradiation on both PLGA and PLLA is chain scission. Chain scission occurs first through scission of the polymer main chain, followed by hydrogen abstraction. Chain scission, though responsible for the reduction in the average molecular weight, Tc, Tg and Tm of both polymers, encourages crystallization in PLGA. PLLA also undergoes chain scission upon irradiation but to a lesser degree compared to PLGA. The higher crystallinity of PLLA is the key factor in its greater stability to e-beam radiation compared to PLGA. A linear relationship is also established between the decrease in molecular weight with respect to radiation dose.
School of Materials Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798, Singapore. joachimloo@hotmail.com
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Loo
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Ooi
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Boey
D004307:Dose-Response Relationship, Radiation; D004337:Drug Carriers / Q000737:chemistry / Q000528:radiation effects; D004583:Electrons; D019344:Lactic Acid / Q000737:chemistry* / Q000528:radiation effects*; D008968:Molecular Conformation / Q000528:radiation effects; D008970:Molecular Weight; D011091:Polyesters / Q000737:chemistry* / Q000528:radiation effects*; D011100:Polyglycolic Acid / Q000737:chemistry* / Q000528:radiation effects*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry* / Q000528:radiation effects*; D011829:Radiation Dosage; D044366:Transition Temperature / Q000528:radiation effects
D004337:Drug Carriers; D011091:Polyesters; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C033616:poly(lactide)