Degradation of Poly(D,L-lactic acid)-b-poly(ethylene glycol) Copolymer and Poly(L-lactic acid) by Electron Beam Irradiation

摘要

This paper investigates the effects of electron beam irradiation on poly(D,L-lactic acid)-6-poly(ethylene glycol) copolymer (PLEG) and poly(L-lactic acid) (PLLA). The dominant effect of EB irradiation on both PLEG and PLLA is chain-scission. With increasing dose, recombination reactions or partial cross-linking of PLEG can occur in addition to chain-scission, but there is no obvious cross-linking for PLLA at doses below 200 kGy. The degree of chain-scission of irradiated PLEG and PLLA is calculated to be 0.213 and 0.403, respectively. The linear relationships are also established between the decrease in molecular weight with increasing dose. The present of poly(ethylene glycol) (PEG) chain segment in PLEG is the key factor in its greater stability to EB irradiation compared to PLLA.