Morphology and enzymatic degradation of thermoplastic starch-polycaprolactone blends

This study's aim was to evaluate the effect of processing conditions on the morphology and enzymatic degradation of 50/50 (w/w) thermoplastic starch-p olycaprolactone blends. The blends, produced from native potato starch, gly cerol, and polycaprolactone in a melt mixer using different mixing speeds a nd temperatures, were cocontinuous, and the blends were very homogeneous. E nzymatic hydrolysis was performed using Bacillus licheniformis alpha-amylas e and Aspergillus niger glucoamylase on both milled and intact samples. The thin layer of polycaprolactone (approximate to 5 mu m) formed on the surfa ce of the thermoplastic starch-polycaprolactone blends during compression m olding strongly reduced the rate of enzymatic hydrolysis. (C) 1999 John Wil ey & Sons, Inc.