The ionic interaction in sulfonated EPDM ionomers containing Li￣+

Na￣+

K￣+

Mg￣(2+)

Ca￣(2+)and Ba￣(2+) has been investigated in solid state。 The existence of ionic cross-linking due to aggregation of M￣+ groups is detected by solubility tests.The infraredspectra(IR ) show that the interaction between sulfonate anion and metal cation decreas-(Institute of Polymer Science

Zhongshan University

Guangzhou 510275)es withionic radiibut increases with valence。The dynamic mechanical analysis(DMA)shows that the width of the rubber platform decreases in the order of Li￣+>Na￣+>K￣+

Mg￣(2+)>Ca￣(2+)>Ba￣(2+) and M￣(2+)>M￣+。 Both IR and DMA indicate that the ionic interactionin sulfonated EPDM ionomers depends on the charge density on cation sulface.