| abstract |
Air is mechanically entrained in an aqueous solution of surfactant, polyamine reactant, and low moisture sensitive poly(oxyalkylene) poly(aliphatic isocyanate) prepolymer the poly(oxyalkylene) portion of which contains sufficient oxyethylene units to render the prepolymer water-soluble and hydrophilic, to form a fluid, water-based, air foam which is sprayed or otherwise applied to exposed surface of a substrate, such as a body of hazardous material, the applied foam gelling or increasing in viscosity, due to reaction of the polyisocyanate prepolymer with the polyamine in the presence of the water to form a poly(oxyalkylene) polyurea polymer containing polyurylene-containing segments formed from the reaction, and forming a persistent gelled air foam or viscous air foam in the form of a coating on the exposed surface, thus sealing or otherwise protecting or controlling the substrate. |