Blends of polypropylene and a commercial biodegradable additive (Mater-Bi AF05H) were subjected to a soil burial test for I year. The effect of the degradation process on the morphology of the blend was studied by differential scanning calorimetry. The melting and crystallization temperatures, degree of crystallinity, lamellar thickness distribution, and crystallization kinetics were analyzed for both the nondegraded and degraded blends and for the pure components before blending and degradation. (c) 2006 Wiley Periodicals, Inc.