Evaluation of a New Approach for Characterizing Environmental Stress Cracking Resistance (ESCR) of Polyethylene

Abstract

A study was conducted to develop a new approach for characterizing environmental stress cracking resistance (ESCR) of polyethylene (PE). The main objective is to reduce time for the testing, to be shorter than that required for the current standard ESCR tests. The new approach applies indentation to generate deflection in the central region of a PE plate, and uses time for crack generation under constant displacement, during the exposure to an aggressive agent, to characterize ESCR. The indentation introduces stretch to a central annular region around the indenter, in which PE molecules are increasingly oriented in the stretch direction. Since this annular region is subjected to bi-axial tension, exposure to aggressive agent increases its vulnerability to crack formation in the stretch direction. ESCR is characterized by the time needed for crack formation during the exposure to an aggressive agent (10% Igepal CO-630 solution). This paper presents the test set-up for the new approach, and compares time for the crack generation using this new approach with that from ASTM D1693, condition A.