A new approach is proposed to analyze the fracture behavior with crack tip plasticity by the use of three independent measurements: E0 is the energy required per unit length of crack front to prepare the crack just before propagation; the Ef-curve is a plot of the energy required to produce a unit area of fractured surface versus the crack length; and the Ka-curve is a plot of the applied stress intensity factor KIapp versus the crack length. For ABS polymers, the prefracture energy E0 is 33 Jm-1; the Ef-curve is a horizontal line of 5.2 × 104 Jm-2; and the Ka curve has three different regions which depend on the development of the plastic zone during fracture
