The biodegradability of polyester blends.

Blends of poly(epsilon-caprolactone) (PCL) and poly(L-lactic acid) (PLLA) with polyglycolic acid-co-L-lactic acid (PGLA) were prepared by three methods: compression moulding, coprecipitation, and solvent evaporation of a methylene chloride-in-water emulsion of the polymers. The rates of hydrolytic chain scission of each component of the blends were determined by deconvolution of GPC traces of samples maintained in phosphate buffer, pH 7.4, 37 degrees C, for up to 3000 h. The observed rates were dependent on the method of blending. For compression moulded blends, the rate of chain scission of PGLA was decreased and that of PCL and PLLA increased. A corresponding delay in the onset of weight loss was also observed. There was no evidence of blend miscibility.