Observation and understanding of the tear mechanism of polyethylene blown films at variable loading angles

Tear is a key physical property of polyethylene (PE) blown films. There are many variables that affect the overall tear property, such as tear path and plastic deformation wake. In this study, five blown PE films are prepared and tested by the Elmendorf tear test at five sampling angles, i.e. 0 (MD), 30, 45, 60, and 90 (CD) degrees. Statistical analysis is carried out on the tear values and the variation of the tear data is investigated based on the observation of the tear samples. The mechanism of severely curved crack, i.e. J-tear, is also studied to understand the tear property variation of blown PE films. In addition, the relationship between tear values and tensile toughness in perpendicular direction is investigated to understand the role of a process zone lying in front of a crack tip during tear. POLYM. ENG. SCI., 54:1038–1046, 2014. © 2013 Society of Plastics Engineers