The effect of fiber inclusions in toughened plastics—part I: fracture characterization by essential fracture work

The effect of fiber inclusions on toughened plastics was studied by means of the technique of essential fracture work. The major advantage of the technique for fiber-reinforced toughened polymers is attributed to its potential to distinguish fiber-related toughness from fiber-induced matrix toughness. Strictly speaking, the essential fracture work is the specific energy required to create two new surfaces and that consumed in the fracture processes involved. The essential work was only proportional to the ligament area whereas the work dissipated outside the process zone was dependent on the volume of plastically deformed region. The latter is not a material property. Fiber-related fracture work, such as fiber bridging, breaking and pullout, can scale with the ligament length but cannot scale with the ligament squared. With fiber inclusions, supertough Nylon 6,6 exhibited concomitant strengthening and toughening.