Effects of in vitro degradation on properties of poly(DL-lactide-co-glycolide) pertinent to its biological performance

Poly(DL-lactide-co-glycolide) (PLGA) is a widely used biodegradable polymer. In this study, effects of in vitro degradation on its dynamic mechanical properties, thermal behavior, molecular weight, fluid uptake and dimension stability were investigated. The in vitro experiment was conducted at 37 degreesC in phosphate buffer solution with pH=7.4 in a dynamic incubator. The dynamic mechanical experiments were performed on rectangular specimens under three point bending. For an aging period of 6 weeks, the dynamic mechanical properties were found to decrease significantly with the increased time. The absorbed fluid had a significant effect on polymer storage modulus. The molecular weight decreased with aging time, and was found to be different at the center and the surface, being higher at the center in the beginning and lower thereafter. The polydispersity did not change significantly with degradation. The fluid uptake and specimen geometric dimension increased proportionally with aging time. The glass transition and thermal decomposition temperatures decreased with the increased degradation time. (C) 2002 Kluwer Academic Publishers.