Preparation of a High-Expansion-Ratio Blend Foam with Low Thermal Conductivity Using Poly(vinyl alcohol)-Polycaprolactone Mixture Solution via Supercritical Carbon Dioxide Foaming Technology

Energy consumption in the field of heat preservation increases every year, so it is important to develop foam with a good thermal insulation properties. In this work, a method for the fabrication of poly(vinyl alcohol)-polycaprolactone (PVA–PCL) blend foams with high expansion ratio and low thermal conductivity using PVA–PCL mixture solution via supercritical carbon dioxide (scCO2) foaming was proposed. A high water content in the mixture solution was used as the coblowing agent, and the differences in foaming behaviors between PVA and PCL were used to introduce large cells into the foam, which together increased the expansion ratio of the PVA–PCL blend foam. The effects of PCL content, saturation time, saturation temperature, saturation pressure, and the assistant solvent (water) on the foaming behavior of PVA–PCL mixture solution in scCO2 were investigated. The results show that the PVA–PCL blend foam has a high expansion ratio (44) and low thermal conductivity (25.97 mW·m–1·K–1).