Microstructure and fracture behavior of polypropylene/ barium sulfate composites

The microstructure, mechanical properties, and fracture behavior of polypropylene (PP)/barium sulfate (BaSO₄) composites were studied. Four composite samples with different PP-BaSO₄ interface were prepared by treating the filler with different modifiers. The fracture behavior of the composites under different strain rates was studied by means of Charpy impact tests and essential work of fracture (EWF) tests. It is shown that a moderate interfacial adhesion is favorable for toughening, which ensures that the particles transfer the stress and stabilizes the cracks at the primary stage of the deformation, and satisfies the stress conditions of plastic deformation for matrix ligaments subsequently via debonding. Very strong interfacial adhesion is not favorable for toughness, especially under high strain rate, because the debonding-cavitation process may be delayed and the plastic deformation of matrix may be restrained.