New Developments in Ethylene Acrylic Elastomers (AEM) – A Review

Ethylene acrylic elastomer (AEM), introduced in 1974 under the brand name Vamac®, is used in many automotive applications where a combination of oil and high temperature resistance with excellent damping properties is required. The trends of increasing temperatures under the hood, more aggressive automotive fluids, reduction in hydrocarbon emissions and longer part life has led to a significant increase of AEM in vehicles over the past decade. AEM has replaced many lower performance elastomers to meet these increasingly demanding requirements.

Developments are underway to modify the AEM offering in order to extend its performance and processing range. Product modifications are directed at enhancing dry heat resistance, low temperature flexibility, productivity and service fluid resistance without sacrificing existing performance characteristics. These developments have resulted in the introduction of new grades and a better understanding of the performance range of existing grades.

The properties of commercially available AEM grades, new applications and developments as well as performance in new automotive fluids are reviewed.