Thermoplastic Elastomer Compounds from Sulfonated EPDM Ionomers

Abstract

Abstract The zinc sulfonate of EPDM, an ionic elastomer polymer, can be readily formulated into useful thermoplastic elastomer compounds having beneficial properties and processing characteristics. The thermoplastic processing characteristics of these ionic elastomers are uniquely controlled by “ionolyzers,” preferential ionic plasticizers. These additives induce thermal reversibility in the ionic crosslink and control the response of the ionic associations to temperature. Ionic elastomer compounds maintain many of the performance features characteristic of vulcanized EPDM, such as low-temperature flexibility, thermal stability, and weatherability, while providing the added advantages of heat weldability and elimination of vulcanization. We have developed a cost-effective ionic elastomer formulation that meets or exceeds the RMA recommendations for black EPDM in a demanding, high performance application, single-ply roofing membrane. High-strength lap seams can be rapidly fabricated using portable hot air welders, a technique unavailable to conventional vulcanized EPDM sheet. Other applications have been investigated for these polymers, such as hose, footwear, mechanical goods, adhesives, impact modifiers, and asphalt modifiers both as thermoplastic elastomers and as modifiers for other materials. These applications have taken advantage of the unique rheological and solubility properties of these polymers. In addition, a new polymer grade offers an advance in the ability to formulate higher strength and more highly filled and extended ionic elastomer compositions.