Evaluation of the tear properties of polyethylene blown films using the essential work of fracture concept

In the case of very thin materials such as blown films, the applied stress state in front of the crack tip is normally a plane stress condition, and the deformation around the crack tip due to the remote stress is very large. However, current standard test methods for quantifying the fracture toughness of thin films, such as the Elmendorf tear test, cannot explain or represent the tear characteristics accurately. The common way of interpreting the test results from the Elmendorf tear test is to develop an empirical correlation and then compare the average values. In this paper, essential work of fracture (EWF) tests for five commercial polyethylene (PE) blown films have been conducted, and the fundamentals of their tear properties based on fracture mechanics have been studied. The results from the EWF test are interpreted based on two important parameters, i.e., the essential work of fracture (W_e) and the non-essential work of fracture (W_p). Further, the relationship between these parameters and the current standard Elmendorf tear test is shown.