Underhood elastomer components: DuPont™ Vamac® Ultra raises the high temperature bar in AEM performance
Ethylene acrylic elastomers (AEM), such as DuPont™ Vamac®, have been used successfully for many years in demanding automotive applications including seals, CVJ boots, dampers and hoses, where excellent resistance to heat, engine and transmission fluids or blow-by gas is required.
The performance of standard Vamac® grades has been proven in countless applications where the AEM delivers vehicle-lifetime service in continuous temperatures up to 165°C, with peaks as high as 180°C. Yet the performance of the latest Vamac® AEM grades exceed even that high temperature ceiling.
In 2007, DuPont introduced the Vamac® Ultra series, an innovative family of AEM polymers offering enhanced properties that extend significantly beyond the performance of standard AEM.
“Since the introduction of Vamac® Ultra, the automotive industry has witnessed a major step up in the ability of AEM polymers to resist continuous temperatures of 175°C in charged air systems, with peaks as high as 190°C,” said Alfonso Sanz, EEMEA Elastomers Product Line Manager, DuPont Performance Polymers.
“The new generation of DuPont AEM polymers helps OEMs meet Euro 5 and 6 emissions requirement in seals, hoses and other underhood components, while maintaining flexibility and sealing performance. As a result, we are seeing very successful adoption of the new Vamac® grades in an increasing number of commercial programs with major auto manufacturers, including BMW, Fiat, GM Daewoo, Renault and Volkswagen.”
A broader range of applications has now opened up for AEM with the development of recent high-viscosity Vamac® Ultra polymers offering better resistance to heat and to new and more aggressive fluids — resulting in longer functionality of parts. Vamac® Ultra is now specified for automotive turbo charger hoses for continuous 175°C service with excursions to 190°C. The latest AEM grades also offer high abrasion resistance in applications such as shaft and ball bearing seals.
DuPont's latest manufacturing technology allows polymerization of Vamac® Ultra grades with optimized structure and chemical composition. This provides significant improvements over existing standard Vamac® elastomers, and step-change improvements in processability.
Automotive turbo charger hoses of DuPont™ Vamac® Ultra AEM provide continuous 175°C service with excursions to 190°C.
Vamac® Ultra grades offer the following improvements over standard AEM polymers:
- Improved injection moldability, better compound flow, reduced mold fouling and increased mold cleaning intervals.
- Less blistering in compression molding.
- Better and faster dispersion of fillers and other compounding ingredients, especially in low hardness compounds or in formulations with high plasticizer levels.
- Equal or better compression set properties.
- Improved dynamic fatigue and stress-strain resistance at high temperature, and better property retention after heat aging.
- Greater flexibility at low temperature.
- Significantly better tensile and tear strength and elongation at break, plus sandpaper abrasion and resilience values.
- Reduced ageing in dry heat and oil resulting in better sealing force retention in CSR tests in air at elevated temperature.
For more information about the capabilities of modern AEM polymers, read “Vamac® Ultra – New High Viscosity AEM Polymers with extended Application Possibilities”, a technical paper given at the International Rubber Conference 2009, Nuremberg on 29 June-2 July, by Klaus Kammerer, Technical Consultant – Vamac®, DuPont Performance Elastomers, click here .