prepolymer molding

prepolymer molding

[prē′päl·i·mər ′mōld·iŋ]
(engineering)
A urethane-foam-producing system in which a portion of the polyol is prereacted with the isocyanate to form a liquid prepolymer with a pumpable viscosity; when combined with a second blend containing more polyol, catalyst, or blowing agent, the two components react and a foamed plastic results.