Effect of Mechanical Constraint on Tearing Energy of Polymer Membranes

The role of mechanical constraint on the tearing behavior of perfluorosulfonic acid and polyethylene membranes is examined. A constrained tearing test is employed to measure the tearing energy when the formation of a plastic zone ahead of the tear tip is constrained. It is shown that the tearing energy decreases with increasing constraint associated with a smaller plastic zone and is much lower than the tearing energy with no constraint. Furthermore, it is demonstrated that the tearing rate has a strong effect on the tearing energy when the membrane is unconstrained, but a much smaller effect when the membrane is constrained as the viscoelastic relaxation processes related to the plastic zone are suppressed. The results highlight the significant role of mechanical constraint on the tearing behavior of membranes during both testing and in application.