EFFECT OF THERMAL CONDITIONS ON THE CLUSTER FORMATION OF SULFONATED POLYSTYRENE IONOMERS

The effect of thermal conditions on the clustering of sulfonated polys tyrene ionomers was investigated. It was found that when the zinc-sulf onated ionomer was dried above a matrix glass transition temperature ( T-g), the cluster T-g was observed at ca. 310 degrees C, which is ca. 45 degrees C higher than that for the ionomer dried below the matrix T -g. This difference is believed to be the result of the increase in ch ain mobility at higher temperatures, which improves the multiplet form ation and clustering; thus the cluster T-g increases. In the lithium i onomer case, however, the increase in the cluster T-g was ca. 6 degree s C upon annealing. From the results, it was suggested that in the zin c ionomer, the zinc ion is soft and divalent, which results in weaker interactions in multiplets, and thus decreases the stability of the mu ltiplets. Therefore, the thermal effect is more significant for the zi nc ionomers than for the lithium ionomers.