Insulation Compounds Based on Blends of EPM and EPDM Polymers For Wire And Cable Applications

This study compares conventional EP(D)M elastomers, metallocene EP(D)M elastomers, and their binary blends in filled compounds designed for low voltage (LV) and medium voltage (MV) cable insulation.  The ethylene propylene copolymers and ethylene propylene diene terpolymers studied were synthesized using either conventional Ziegler-Natta or single-site metallocene catalysts.  The compounds examined were prepared from either a single EP(D)M polymer or a binary EP(D)M polymer blend, calcined clay, peroxide curatives, and other additives in a common insulation formula known in the wire and cable industry as “3728”.  A comparison of the key performance attributes of these compounds is made, including cure characteristics, physical properties, heat-aged physical properties, wet electrical properties, and aged wet electrical properties. 
Many of the compounds evaluated have a favorable combination of properties that indicates good potential for their use in medium voltage wire and cable insulations. The results of this study should be of significant interest to wire and cable insulation compounders pursuing the development of novel compounds with enhanced properties and lower cost.