Environmental Stress Cracking Resistance (ASTM D 1693)
Specimen: LDPE measuring 1/8 x ½ x 3/2 inches, annealed in water or steam at 100 0 C for 1 hour and then conditioned at room temperature for 5 to 24 hours.
The specimen is placed in an air circulating oven and then inserted in a test tube which is then filled with a fresh reagent [Igepal = RC6H4O(CH2CH2O)nCH2CH2OH where R is C6H17 or higher homolog]. The tube is stoppered with an Aluminum covered cork and placed in a constant temperature bath at 50 0C. These are inspected periodically and any visible crack is considered as failure. The duration of the test is recorded along with the percentage of failure.
Significance:The cracking obtained in this test indicates what can be expected from a wide range of other stress cracking agents. Though the information cannot be translated directly into end use service prediction, but it serves to rank various types and grades of PE in categories of resistance to stress cracking. This test can also be used on high and medium density used on high and medium density material.