Abstract: Described are viscoelastic polyurethane foams that comprise the reaction product of a polyisocyanate and an active-hydrogen composition comprising an amidated or transesterified oligomeric natural oil polyol.

Abstract: Described are viscoelastic polyurethane foams that comprise an oligomeric natural oil polyol and a petroleum-derived polyol. The viscoelastic foams are formed by reacting a polyisocyanate with an active-hydrogen composition that comprises the oligomeric natural oil polyol and petroleum-derived polyol.

Abstract: Flexible polyurethane foams prepared from formulations requiring reduced amounts of chlorofluoro-carbon blowing agents are disclosed. The foams can be prepared without undesirable loss of physical properties with formulations comprising an "A" component which is a blend of a polymethylene polydiphenyldiisocyanate and a methylene diphenyldiisocyanate prepolymer wherein the methylene diphenyldiisocyanate prepolymer is prepared from a prepolymer formulation containing an active hydrogen containing compound which has an equivalent weight of about 30 to about 600; a "B" component which includes an active hydrogen containing compound; and a carbon dioxide generating blowing agent. Also disclosed are polyisocyanate blends consisting of polymethylene polydiphenyldiisocyanate and methylene diphenyldiisocyanate prepolymers useful for preparing flexible polyurethane foams. Methods of preparing both the foams and the polyisocyanate blends are also disclosed.