Increased worldwide environmental pressure has made it necessary for polyurethane foam processors to eliminate chlorinated products, such as chlorofluorocarbons (CFCs) and methylene chloride, and other volatile organic compounds (VOCs) from their production atmosphere; these products have historically been utilized by the polyurethane industry to perform the vital function of expanding agents for foam. As a result, the industry has been undergoing an intensive search for viable, readily available, and safe alternatives to these products. These alternative products have been labeled ABAs (alternative blowing agents).The oldest and simplest known blowing agent for polyurethanes is carbon dioxide (CO2), a nonhazardous chemical, capable of expanding foams down to a very low density. For this application, carbon dioxide has been incorporated - thus far - by reacting isocyanate with water (i.e. producing “chemical” carbon dioxide), by blending it into the polyol prior to processing or by directly adding it at the mixing head.