Biodegradable polymer foams prepared with supercritical CO2–ethanol mixtures as blowing agents

Polycaprolactone (PCL) foams were produced with the batch foaming technique using CO2–ethanol supercritical mixtures as blowing agents. Experiments were preformed at 35–45 °C and 123–205 bar. The effect of pressure, temperature, and ethanol content of the blowing agent on the final porous structure was investigated. The results revealed that difficulties in the foaming of polymers related to their crystalline structure could be overcome with the addition of small amounts of organic solvents. The porous structures that were obtained using pure CO2 as blowing agent were not homogeneous and consisted of regions with different pore sizes and pore densities. On the contrary, the structures that were obtained with the addition of small amounts of ethanol were more uniform in nature with larger pore sizes.