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 separation between crack initiation and propagation fracture parameters is done 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 different 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 the "Initiation Specific Essential Work" (w(e)(I)) seems not to be sensible to the stress-state transition