In order to meet governmental requirements for automotive fuel economy, light weight materials must replace conventional materials. Reinforced reaction injection molded (RRIM) polyurethanes are expected to play a major role in weight reduction. Variations which must be considered in producing RRIM include the machinery, resin matrix, reinforcing material, and processing effects. Suitable production equipment appears to have been developed. Milled glass fiber reinforced RIM appears ready to compete on a commercial basis with SMC and BMC for exterior automotive applications. RRIM parts are self-supporting in thin sections, have a coefficient of thermal expansion approaching that of steel, and have very low shrinkage rates.
