RUBBER TOUGHENING OF POLY(LACTIDE) BY BLENDING AND BLOCK COPOLYMERIZATION

Copolymers of L-lactide with 15 or more mole % D-lactide are amorphous , noncrystallizable hydrolytically degradable materials. These glassy materials are brittle in tension and bending. To make these materials suitable for use as load-bearing devices in biomedical applications, t oughness has to be enhanced. This is effectively accomplished by intro ducing a separate degradable rubber phase in the amorphous matrix. Sev eral approaches have been explored: solution blending and coprecipitat ion of trimethylene carbonate and epsilon-caprolactone rubbers and pol y(lactide), preparation of ABA triblock copolymers and blending of ABA block copolymers with the amorphous poly(lactide) matrix. In all case s very tough materials could be prepared. These materials are easily p rocessable by compression molding at relatively low temperatures.