EFFECT OF SAMPLE HISTORY ON IONIC AGGREGATE STRUCTURES OF SULFONATED POLYSTYRENE IONOMERS

The effects of thermal treatment and of solvent (dimethyl formamide (DMF)) history on the ionic aggregate structures of lightly sulphonated polystyrene ionomers were studied by dynamic mechanical measurements. It was shown that thermal treatment of the ionomers with 2.5 mol% ion content enhanced cluster formation. It was also found that DMF worked as a 'dual' plasticizer that not only destroyed ionic aggregates but also decreased the T(g) of matrix materials. Thermal treatment of cast samples from DMF recovered ionic aggregate structures that were comparable to those seen in compression-moulded samples.