A novel method to produce lightweight microcellular injection molded parts with improved ductility

A novel method of improving the ductility of injection molded plastic parts has been developed. By applying either gas-laden pellet technology or microcellular injection molding to polymer blends or composites of proper material formulations, the ductility and toughness of the molded foam parts can be significantly improved compared to those of solid parts. The key is to achieve a microcellular structure with a sub- micro scale immiscible secondary phase. Upon tensile loading, cavitation of the secondary phase facilitates the interconnection of microcellular voids to form channels such that the stretched component becomes a bundle of fibrils. This change in structure turns the fracture mechanism from crack propagation across the matrix into shear yielding of a bundle of fibrils in the loading direction. Compared with other toughening methods, this method achieved a more significant improvement in ductility and toughness with reduced material consumption and lighter part weights.