Rubber toughened linear and star-shaped poly(d,l-lactide-co-glycolide): synthesis, properties and in vitro degradation

Blends of D,L-lactide/glycolide copolymers were synthesized and their properties and in vitro degradation behaviour were evaluated as a function of chain architecture and blend composition. Tensile and impact properties of the blends are hardly influenced by matrix composition and chain architecture, but predominantly vary with the amount of rubber. In vitro degradation showed that hydrolytic degradation is enhanced by the incorporation of glycolide into the poly(D,L-lactide) matrix. Surprisingly, blends based on 6-arm star-shaped poly(D,L-lactide-co-glycolide) retain their mechanical properties for a longer period than blends with linear matrices of comparable composition. Physical aging of the linear copolymers is more severe and faster than that of star-shaped copolymers. (C) 1997 Elsevier Science Ltd.