| Abstract: | The impact fracture mechanisms of rubber-toughened nylon are analyzed by measuring the energy dissipated in several different processes during notched fracture. An energy balance is thus established for the impact fracture. The stress-whitened zone is shown to be the energy dissipation zone, having an energy dissipation density of 5.30 cal/g. About 25% (i.e., 1.44 cal/g) of the impact energy is dissipated by matrix crazing. About 75% (i.e., 3.86 cal/g) is dissipated as heat by matrix yielding, causing a temperature rise of 9.1 °C in the energy dissipation zone. Surface energy storage on the fracture surfaces is negligible (i.e., 1.45 × 10?5 cal/g). During matrix yielding, about 12% of α-triclinic nylon crystals is transformed into pseudohexagonal crystals. |
