Mesostructure development during molding of sheet molding compounds

Abstract Experiments have been carried out with sheet molding compounds in which the amount of shear developed during molding was varied by changing the charge size. The effects of pressure and temperature were also investigated. The moldings were characterized by their mesostructures and the influence of the mesostructures on the Izod toughness and flexural strength was examined. It was found that high degrees of shear resulted in fiber orientation and the spreading of the fiber bundles. However, this did not improve properties, and it was concluded that for optimum properties, small amounts of shear were desirable.