Evaluation of fracture characteristics of polyethylene blown films using the Essential Work of Fracture (EWF) with variable film orientations

In this paper, essential work of fracture (EWF) tests for five polyethylene blown films are conducted. The fracture toughness of those samples was evaluated based on test results. The effect of the film orientation on the fracture toughness of materials was evaluated. The work calculated from load-displacement curves obtained from double edge-notched tension (DENT) specimens was analyzed as the ligament increases. In the case of MDPE, a sudden rise of the fracture toughness and the slope is evident at the crack angle from 30 to 60 degree, and LLDPE case, the variation of the observed slope of high angle (60-90 degree) cracks is not that much different than that of low angle (0-30 degree) cracks. The slope of the EWF test, which indicates the energy dissipation, yields the reduction of compliance during crack propagation.