High abrasion furnace carbon black improves the physical properties of zinc sulfonated ethylene-propylene-diene terpolymer of high (75 wt%) ethylene content. Properties studied include hardness, stress-strain characteristics, tear strength, hysteresis and abrasion resistance. Scanning electron photomicrographs of the tear fractured and abraded surfaces show changes in failure mode of the polymer on incorporation of carbon black. Results of dynamic mechanical analyses and dielectric thermal analyses show that carbon black reinforces the ionomers, presumably through weak rubber-filler interaction involving the backbone chains and strong interaction between the active sites of the filler surface and the ionic aggregates present in the ’multiplets’ and ’clusters’. Reprocessability studies in the Monsanto Processability Tester (MPT) show that the carbon black filled polymer can be reprocessed like a thermoplastic elastomer and there was no fall in properties even after three cycles of extrusion through the MPT.