Blends of CO2 and 2-ethyl hexanol as replacement foaming agents for extruded polystyrene

By the year 2010, HCFC 142b will be banned for use as a foaming agent for extruded polystyrene (PS) foam in North America. Many blends of foaming agents have been patented as replacements to expand PS. In this study the optimal concentration of a previously unexplored blend of CO2 and 2-ethyl hexanol (2-EH) is shown to allow the production of PS foam of 30 kg/m(3) density. The glass transition temperature reduction of the PS, due to the incorporation of 2-EH, is believed to be an important contributor to the success of this foaming agent blend. In long-term use of the foams, the 2-EH does not measurably diffuse out of the PS whereas the half-life of CO2 diffusion out of the foam is measured in weeks.