A novel class of polyols for polyurethane production was described in 19661. Their unique feature was the presence of an in situ polymerized vinyl polymer which markedly enchanes the modulus of the resultant polyurethane. The final product is a conventional polyol that contains a dispersion of the vinyl polymer. From among the numerous products investigated, a poly-(acrylonitrile) polyol was selected because of the excellent stability of the dispersion. Poly (acrylonitrile) polyols are opaque, cream-colored liquids with viscosities ranging from 1500 to 4500 cps, depending upon the nature of the polyol precursor. Particle size of the dispersed phase was reported to be between 0.25 and 0.5 micron as determined by electron microscopy. Poly (acrylonitrile) polyols have been used in slab-stock flexible foams as additives to conventional polyether polyols to improve load-bearing properties. More extensive utility has been identified in molding applications. Whitman described their use in producing integral skin urethane foams for uses such as automotive arm rests, horn buttons, mirror covers, etc.. Dunleavy discussed the use of polymer polyols in molded, microcellular urethane elastomers for automotive trim parts, particularly for "cosmetic" bumpers. More recently, Patten and Priest showed their utility in highly resilient automotive seating foam. In all of these applications the modulus enhancing characteristics of these polyols are particularly important.