Fracture behavior of kaolin-reinforced high density polyethylene

The addition of the low-cost mineral filler kaolin to high-density polyethy lene (HDPE) creates a composite with both improved stiffness and toughness properties. This study focuses on two aspects of the toughness of these com posites: the fracture toughness increment produced by work at the fracture surface and the directionality induced by the injection molding fabrication process. The Essential Work of Fracture (EWF) method gives results which s how that a higher volume fraction of kaolin produces more surface work, con sistent with earlier work using Compact Tension (CT) rests. The EWF method also demonstrates that a lower volume fraction can produce a higher overall plastic work and apparent toughness. A hear treatment that removes the ori entation of the matrix but not that of the particles was applied to study t he effect of matrix crystallinity. The results indicate that the matrix sup ramolecular structure (crystallinity and skin-core effect) is responsible f or the directionality of toughness, and that a heat treatment cart be used to produce high roughness behavior in both major directions.