ABSTRACT
Hansen solubility parameters (HSP) can be used to help predict which chemicals can cause environmental stress cracking (ESC) in polymers. ESC requires tensile stress and correlates when the RED number (relative energy difference in the polymer-solvent interaction) found from HSP considerations is plotted vs. a molecular size parameter, the molar volume, V. There are three distinct regions on this plot. There is a region at low RED including those challenge liquids that dissolve the polymer or are very aggressive, and ESC is not found as such. There is a region at high RED where the absorption is zero or not great enough to matter or else the absorption rate is slow enough to allow relaxation of the polymer in preference to ESC. ESC can occur in an intermediate region where there is some absorption of challenge liquid, although examples are given where ESC takes place without measurable absorption for good matches in HSP at relatively high stress/strain. The ESC region on these plots increases in size with increased tensile stress and/or increased critical strain.
