Propagation Tear Resistance of Plastic Film and Thin Sheeting by Pendulum Method (Elmendorf Tear) ASTM D1922

Range:

The pendulum impact testing machine is used to measure the force required to propagate an existing slit to a fixed distance from the edge of the test sample. One use of these results is to specify the material and thickness of the plastic film used in the packaging. Depending on the application, low or high transmission power may be more desirable. 

Test program:

Cut 10 samples from the plastic film along the machine direction and horizontally. Place the sample in the tester and clamp it in place. The cutting blade in the tester is used to form a slit on the sample, with the end of the slit 43 millimeters away from the distal end of the sample. The pendulum is released to propagate the slit to the remaining 43 millimeters. The energy loss of the pendulum is used to calculate the average tearing force.

Sample size:

The Elmendorf tear test has three standard samples. The preferred test sample for plastic film is a constant radius sample. This sample provides a constant radius starting from tear strength measurement - suitable for materials where tearing may not propagate directly upwards as expected. Another common sample is a rectangle measuring 63mm x 76mm. For textiles, the modified rectangle will increase the height of the sample end to help minimize the unraveling of the outer edge.

Data: 

The test results are expressed in millinewtons (or grams) of tearing force. The sample thickness was also reported, although there is no direct relationship between thickness and tear force. Therefore, only the results of samples with the same thickness can be compared.