ASTM D 1693:Environmental Stress  Cracking of Ethylene Plastics "Bent Strip ESCR"

At the Cincinnati Technology Center and other laboratories, Igepal® CO-630, at varying concentrattions, is used as the standard cracking reagent for this test, which is carried out on molded specimens 1/8 in. or ¾ in. thick (depending on the PE type being tested), 1½ in. long and ½ in. wide. The specimens are first heated in boiling water to relax "frozen-in" stresses. A surface cut of a specified length and depth is then made on the sample parallel to the long axis with a mounted razor blade. The specimens are the stressed by bending them 180 degrees. The specimens are then placed in a rack that is put into a test tube containing the stress-cracking agent. To accelerate the effect of the cracking agent, the test tube is placed in a bath at 50°C (122°F).

Periodically, the specimens are inspected for visual cracks perpendicular to the cuts. At each inspection, the number of failures is recorded. A polyethylene resin is considered to have failed when one half of the specimens in the tube show cracks perpendicular to the cuts.

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