A TEST FOR SLOW CRACK-GROWTH FAILURE IN POLYETHYLENE UNDER A CONSTANT LOAD

A test method is described which measures the slow crack growth behavior of polyethylenes. The method involves a constant load test on a notched specimen under plane strain conditions in air at various temperatures. The results of the test method as obtained by ten laboratories show that the intralaboratory precision is 12% of the mean and the precision of the means from the interlaboratory data is 16%. The high precision in the data is partly based on the use of a specially designed notching machine for producing high quality notches in the specimens. The test method simulates the same fracture process that occurs during the long time failure of polyethylenes, but accelerates the fracture process probably faster than any other test method using a constant load in air.