On the essential work of fracture method: Energy partitioning of the fracture process in iPP films

The fracture properties of an iPP are investigated by the EWF method. A sep aration between crack initiation and propagation fracture parameters is don e by splitting the total energy of the load-displacement curves in two. The influence of the DDENT specimen height and the test rate on these differen t parameters is studied, obtaining that varying the height has no influence in the range 40 to 80mm, but changing the crosshead speed (2 to 100mm/min) has an effect on the fracture parameters. It is interesting to note that t he "Initiation Specific Essential Work" (w(e)(I)) seems not to be sensible to the stress-state transition