Toughness of Flake-Reinforced

ABSTRACT: This paper discusses the mechanisms governing the fracture toughness of polypropylene reinforced by either mica or glass flakes. The toughness of these compos-ites is found to be controlled by the competition between shear yielding and voiding in the matrix. Shear yielding occurs around filler particles, because of debonding at the filler/matrix interface. The filler onentation does not affect the crack growth resistance, but there is a unique relationship between the latter and the average distance between par-ticles, regardless of the nature of the filler. It has also been found that the glass-rubber relaxation of the matrix polypropylene is the governing parameter for the time dependence of the dynamic fracture toughness of these composites