watched to evaluate the time to crack formation, which is the way that ESC resistance is quantified. A testing apparatus for this method is known as the Telecom and is commercially available; initial experiments have shown that this testing gives equivalent results to ASTM D1693, but at a much shorter time scale. Current research deals with the application of fracture mechanics to the study of ESC phenomena. In summary, though, there is not a singular descriptor that is applicable to ESC—rather, the specific fracture is dependent on the material, conditions, and secondary chemical agents present . Scanning electron microscopy and fractographic methods have historically been used to analyze the failure mechanism, particularly in high density polyethylene (HDPE). Freeze fracture has proved particularly useful for examining the kinetics of ESC, as they provide a snapshot in time of the crack propagation process. Strain hardening as a measure of environmental stress cracking resistance (ESCR) Many different methods exist for measuring ESCR. However, the long testing time and high costs associated with these methods slow down the R&D activities for designing materials with higher resistance to stress cracking. To overcome these challenges, a new simpler and faster method was developed by SABIC to assess ESCR for high density polyethylene (HDPE) materials. In this method, the resistance of slow crack growth or environmental stress cracking is predicted from simple tensile measurement at a temperature of 80℃. When polyethylene is deformed under a uniaxiial tension, before yield, the stiff crystalline phase of the polymer undergoes small deformation while the amorphous domains deforms significantly. After the yield point but before the material undergoes strain hardening, the crystalline lamellae slips where both the crystalline phase and the amorphous domains contribute to load bearing and straining. At some point, the amorphous domains will stretch fully at which the strain hardening begin. In the strain hardening region, the elongated amorphous domains become the loading bearing phase whereas the crystalline lamellae undergoes fracture and unfold to adjust for the change in strain. The load-bearing chains in the amorphous domains in polyethylene are made of tie-molecules and entangles chains. Because of the key role of tie-molecules and entanglements in resisting environmental stress cracking in polyethylene, it follows that ESCR and strain hardening behaviors can very well be correlated. In the strain hardening method, the slope of strain hardening region (above the natural draw ratio) in the true stress-strain curves is calculated