Prepolymer or Hot-Cast Elastomers
The prepolymer process for producing polyurethane cast elastomers is a two-step procedure. Because most prepolymers are solids at ambient temperatures, the chain extension ("vulcanization") is usually conducted at prepolymer temperatures of 80°C (176°F). For this reason, polyurethane elastomers prepared by the prepolymer process are often referred to as "hot-cast" or "hot-cure" elastomers. These high-performance polyurethane elastomers exhibit excellent elasticity combined with high modulus and resilience, low-compression set, and dimensional stability over a wide temperature range
Hot-cast polyurethane elastomers are used in more demanding applications, such as bumper pads, coated conveyor belts, dead-blow hammers, drive belts, forklift tires and wheels, gears, grain and coal chutes, hydraulic seals, mining screens, pipeline pigs, shaft couplers, sprockets, wheel chocks and more.
See the table at the bottom of this page for a summary of properties and applications for hot-cast elastomers.