Over the past decade, high-density polyethylene (HDPE) materials have improved significantly and now meet more stringent performance standards; some performance evaluation tests that once took only days to run now take months with today’s resins. One such performance criteria is Environmental Stress Crack Resistance (ESCR). Because standard test methods for measuring ESCR on plastics take such a long time (sometimes months) the quality of the material is judged acceptable if the failure time exceeds a certain limit. Many times, the test is terminated before an absolute fracture time is determined. Due to these long testing times, new tests and standards have been developed to differentiate these improved materials more easily.
This technical publication defines Environmental Stress Cracking (ESC) and Environmental Stress Cracking Resistance (ESCR) and why ESCR is an important resin property. It will also describe some of the tests used to measure ESCR in HDPE products and how resin properties influence ESCR.