Blends of polycaprolactone (PCL)/gelatinized starch and polybutylene succinate adipate /gelatinized starch have been prepared in various ratios and their phase morphology and thermal/mechanical properties have been analyzed. For both the PCL/plasticized starch and polybutylene succinate adipate/plasticized starch blends the resistance to impact increased with increasing polyester content, and the tensile modulus reached a maximum at around 80 wt % polyester content. hi blends containing up to 70 wt % polyester (as observed by scanning electron microscopy) a hierarchical dispersion of the gelatinized starch phase was observed (distinct domain sizes of those less than 5 pm and those greater than 15 mu m) and in the blends containing 70-90 wt % polyester a more singular dispersed phase of gelatinized starch was observed within the polyester matrix. Dynamical mechanical analysis results showed some phase mixing was present in the PCL/gelatinized starch blends noted by the appearance of an additional tan delta peak located between the glass transition temperatures of the respective components and broadening of the low temperature transition corresponding to the T-g of the polyester (possibly the result of a starch-rich polyester phase) with some overlap with the low temperature beta transition of the gelatinized starch itself. (c) 2006 Wiley Periodicals, Inc.