It is interesting to note that the effect of temperature on feiet may be partially offset by the change in solubility which accompanies the change in temperature. (35) Freedman, .
Metal sulfonate groups were introduced into an ethylene--propylene-diene monomer terpolymer (EPDM) via reaction of its residual unsaturation with acetyl sulfate, followed by neutralization of the resultant polymeric sulfonic acid with metal acetates. The composition, structure, and molecular weight of the EPDM and the sulfonate content, cation borne by the sulfonate group, and metal acetate concentration of the ionomer were found to substantially affect the rheological and mechanical properties of the ionomer. Through the proper selection of EPDM backbone, EPDM molecular weight, and sulfonate content, and through the use of the zinc cation, it was possible to prepare EPDM--based ionomers with excellent mechanical properties and with the lowest possible melt viscosities. Although formulations derived from these zinc sulfonate-containing EPDM's possess melt viscosities that are higher than desirable for facile processability, in many respects they are truly thermoplastic elastomers.HPhe presence of small amounts of ionic groups in hydrocarbon polymers exerts a profound effect on their physical properties (1,2). The polymers are effectively cross-linked through the association of these ionic groups forming multiplets or higher order associations described as "domains." These associations can be thermally relaxed to a greater or lesser extent depending on the composition of the ionic domains. In elastomeric systems, if the degree of ionic association at processing temperatures is sufficiently reduced to permit adequate melt flow, then the ion-containing elastomer is a thermoplastic elastomer.Carboxylate-containing elastomers and the effects of the free acid and metal carboxylate groups on elastomer properties have been studied 0-8412-0482-9/80/33-187-003$05.00/0
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