Use of high modulus, impact resistant foams for structural components

Abstract

The present invention provides tough, high modulus, low density thermoset polyurethane compositions which are useful in general as, for example, cast structural materials and in a preferred embodiment can be cured directly onto an aircraft engine fan blade, thereby providing a lighter blade, without concomitant loss in structural integrity or blade performance due to, for example, resistance to foreign object impacts and fuel efficiency. In a preferred embodiment, the composition is comprised of bis-amine compounds reacted with isocyanate-functional polyether polymers in the presence of hollow polymeric microspheres. The thermoset polymer compositions are formed by casting into a mold which is formed by a cavity within the metallic or composite fan blade or guide vane in the form of a pocket and a removable caul sheet. After the elastomeric polyurethane foam is injected through at least one injector port into the mold, the foam is cured.