AEM Compounds with Improved Heat Resistance

AEM compounds meet the needs of many automotive under the hood applications with a combination of good heat resistance, low temperature flexibility and fluid resistance. As engine temperatures and warranty durations increase, the heat aging specifications are becoming more severe and may reach or exceed the limitations of standard AEM compounds.

Recent advances in AEM compounds provide a 15°C improvement in heat aging properties based on the criteria: maximum 15 point change in hardness and less than 50% loss in both tensile strength and elongation. The heat aging advantage is achieved with no loss of the low temperature properties or the good fluid aging properties.

The improved heat aging properties result from replacing conventional black or mineral fillers with a polymeric filler that has good adhesion to the AEM elastomer. The polymeric filler overcomes the adverse effect of the conventional fillers during heat aging and it actively promotes the oxidative stability of AEM compounds.

The improved heat aging properties are useful for many applications such as turbocharger hoses, molded air ducts and the seals and gasket market. The improved oxidative stability of the polymer filled AEM provides a major advantage for the seal and gasket market: significantly improved Compressive Stress Relaxation properties in hot air.

While carbon black has been and will continue to be an important raw material for AEM compounds, it has some inherent limitations such as not allowing for different colored compounds. Unlike mineral fillers, the polymeric filled AEM can be used to make different colored (red, green, blue, etc) compounds without sacrificing desirable properties such as resistance to compression set. The polymer filled AEM compounds can also be used to make low hardness compounds that have relatively good properties and processing – something difficult to achieve with black filled compounds.