Characterization of aluminum foam–polypropylene interpenetrating phase composites: Flexural test results

A type of interpenetrating phase composites was formed by impregnating 90%-porous open-cell aluminum foam with polypropylene through an injection molding process. Three aluminum foams were used having three distinct linear pore densities: 10, 20 and 40 pores per inch (ppi) or roughly 4, 8 and 16 pores per cm. Samples taken from these composites were tested for flexural strength and stiffness based on ASTM D790-03. Flexural modulus and strength of the composite are compared to those of unreinforced polypropylene. The results showed, in general, the combination of the polymer and metal foams to be stiffer than either of the two individual components. The stiffness of the composites was found to increase with decreasing pore size. The smaller pore size allowed more cells to exist across the thickness of the specimen, and thus increased the bending stiffness of the composite.