Biodegradable polycaprolactone/chiotosan blends with various proportions wet e prepared Using concentrated acetic acid solutions as solvents. The blends were further processed into thicker membranes using a newly developed processing technique. These membranes were then investigated for their miscibility of components via thermogravimetric examinations, differential scanning calorimetric measurements, and dynamic mechanical analysis as well infrared analysis. The presence of phase separation structures inside the membranes was confirmed although very limited interactions between components were detected. In addition, it Was also found that the composition ratio of the membranes did not substantially affect the interactions between the components inside the membranes. (C) 2009 Elsevier B.V. All rights reserved.