The foaming process of poly(e-caprolactone) (PCL) with carbon dioxide and nitrogen was investigated from theor. and exptl. view points. CO2 and N2 showed very different behavior, as foaming agents for PCL. This was due to the different transport, chem., and phys. properties of the polymer/gas mixt. that led to different foam morphol. in terms of d., cell no. d., and cell size. The lowest d. (0.03 g/cm3) was obtained with CO2, but the highest no. of cells with N2 Vectra B 950although with a higher d., (0.2 g/cm3). Foam with a low-d. microcellular structure, was obtained when a mixt. of the two gases was employed
