Improved AEM Dipolymer – Peroxide Curable

Most AEM polymers are terpolymers of ethylene, methyl acrylate and an acidic cure site monomer.  The compounds made from the AEM terpolymers are cured with diamines and they require a post cure step to ensure good compression set properties and good heat aging properties.   Peroxide cure systems are not preferred for AEM terpolymers because the cure site monomer interferes with the peroxide cure system. 

Recent advancements in the architecture of AEM terpolymers have been applied to an AEM dipolymer (ethylene and methyl acrylate – no cure site monomer) and this polymer is peroxide curable.  Compounds made with the improved dipolymer process significantly better than compounds made with the older generation AEM dipolymer.  For the injection molding process, the compounds made from the improved dipolymer have less sticking in the molds, less mold fouling and better hot tear.  In the extrusion process, compounds made from the improved dipolymer have higher green strength and less die build-up.

Compound development work has been done with the improved AEM dipolymer to optimize the trade-off between good compression set, good dynamic properties, good fluid resistance and good low temperature properties. 

The cure systems for these compounds have relatively fast cure times and a post cure step may not be needed.  An option to ensure good compression set properties is to use a continuous post cure oven as part of a “lean” manufacturing process.  The suggested time in the post cure oven is around ten minutes. 

The improved AEM dipolymer can be formulated with flame retardants for wire and cable compounds.  These compounds have a combination of low flammability, low smoke, good oil resistance, good heat resistance and good processability.