FATIGUE BEHAVIOR OF IONOMERS .2. EFFECT OF COUNTERION ON SULFONATED POLYSTYRENE IONOMERS

The effect of counterion type on the fatigue properties of sulfonated polystyrene ionomers was studied. It was found that the fatigue resistance of samples of the divalent Ca salt is ca. 3 times that of samples of monovalent K and Cs salts. This may be due to a more “effective” ionic cross-linking network in the Ca salt, which tends to suppress crazing in favor of shear deformation. This effect is similar to that found in Na salt ionomers of high ion content, in which the presence of ionic clusters leads to a more stable ionic cross-linking network rather similar to that found in covalently cross-linked PS. © 1990, American Chemical Society. All rights reserved.