Separation of tear energy of polyethylene blown films using essential work of energy

Tear is practically important because it can be varied significantly due to the formation of asymmetric chain and crystal orientation once the processing condition is changed. ASTM has a very practical standard for tear test, i.e. the Elmendorf tear test (ASTM D1922), but this method has been criticized due to its lack of scientific validity. Recently, the essential work of fracture (EWF) test has been shown to be applicable to characterize in-plane tear of polyethylene thin films. In this paper, the relation between out-of-plane tear (i.e. Elmendorf tear) and in-plane tear (i.e. EWF) of five types of high density polyethylene (HDPE) and linear low density (LLDPE) films is experimentally investigated by separating tear energies. In addition, the fundamental mechanism of tear of polyethylene blown films is discussed based on fracture mechanics concepts.