Recent developments in sheet molding compound technology

The molding of fiber-reinforced thermoset components is a complex process involving a highly exothermic chemical reaction, which takes place in the presence of flow and thermal gradients. The flow in turn is complicated by time- and temperature-dependent rheological characteristics. The industry has grown largely on the basis of empirical developments. However, numerous problems do remain which require increased understanding for solution. This report reviews work underway in numerous laboratories to characterize the flow and cure of sheet molding compounds and phenomena associated with these processes such as orientation, mechanical properties, residual internal stresses, mold fill, and surface defects.