Structure optimization of PCL foams by using mixtures of CO2 and N2 as blowing agents

The foaming process of polycaprolactone (PCL) with carbon dioxide (CO2) and nitrogen (N2) has been investigated in this work from a theoretical and experimental point of view. CO2 and N2 showed very different behaviour, as foaming agents for PCL. This was due to the different transport, chemical and physical properties of the polymer/gas mixture, that leaded to different foam morphology in terms of density, cell number density and cell size. The lowest density (0.03 g/cm3) was obtained with CO2, but the highest number of cells with N2 (0.2 g/cm3). The most interesting foam morphology, characterized by a