Trouser tear tests of two thin polymer films

摘要

Trouser tear testing has been concerned in this research work.A polypropylene film and a low density polyethylene film used in the packaging industry are considered.The experimental trouser tear tests showed different results for both materials when they were subjected to load in different material directions.Therefore the hypothesis was verified,that the in-plane material orientation/alignment induced during manufacturing,hence creating anisotropic in-plane mechanical properties,also affects the tearing behavior.A brittle-like failure was shown in the polypropylene film while the low density polyethylene presented a highly ductile behavior.The two polymer films can be classified as one low-extensible and one high-extensible material according to the test method utilized.Material parameters in the principal material directions i.e.manufacturing direction and cross direction were extracted from the experimental tests for further numerical studies.Scanning electron microscope was used for micromechanical and fractographical analysis of the crack tip and crack surfaces created during the tests.The methods discussed will help classify different groups of materials and can be used as a predictive tool for the crack initiation and crack propagation path in packaging material,especially thin polymer films.