A review with 19 references describing the basic principles of non-sagging polyurethane compositions and a wide variety of applications for the technol.Applications for non-sagging polyurethanes include structural adhesives for SMC, expandable caulkings and sealants, furniture edging, carpet seam sealants, and flexible, sandable patching compoundsNon-sagging behavior is an essential property for polyurethane paint and adhesive formulations that are applied onto vertical surfaces.Traditionally, the non-sag property is achieved through additives that control rheol. properties of a paint or adhesive.For waterborne polymers such as latex paints, rheol. modifiers include hydroxyethyl-cellulose, hydrophobically modified alkali-soluble emulsions, and hydrophobically modified ethylene oxide urethanes (associative thickeners).Solvent-based polymers, such as alkyd paints, typically use castor oil derivatives, attapulgite or bentonite clays, or fumed silica.Bayer Corporation has developed a non-sagging polyurethane technol. that overcomes disadvantages associated with these filled systems.This technol. involves the reaction of a liquid polyisocyanate with polyhydroxy compounds and an aliphatic or aromatic amine.The amines may be added to the reaction in an amount sufficient to produce adequate resistance to flow/sag upon mixing of the reactants.Hence, when a bead of polyurethane is applied to a vertical surface, it does not run, drip or sag.Due to the almost immediate reaction of the amine component with the isocyanate, an initial build-up in mol. weight produces the desired non-sagging behavior.The system remains in this "B-stage" for a controllable amount of time before the hydroxy/isocyanate reaction takes place and the system cures to a solid polyurethane.