Vamac® Ethylene Acrylic Elastomer (AEM)
Parts made from Vamac® elastomers have good heat and UV resistance because the polymer backbone is fully saturated. They have good fluid resistance to engine oils and transmission fluids because of the acrylic monomer, along with good low temperature properties. The balance of ethylene and acrylic monomer in the polymer determines the low-temperature properties.
Chemical Resistance Guide
Vamac® DP is an ethylene acrylic dipolymer elastomer. Its general performance characteristics are similar to those of the Vamac® terpolymers, including:
Vamac® G is a terpolymer of ethylene, methylacrylate, and a cure site monomer. It is cured using an amine-based vulcanization system. This gum elastomer includes a small amount of processing aid, and has a nominal specific gravity of 1.03. Vamac® G has excellent high-temperature durability and oil resistance with service lubricants, coupled with good low temperature flexibility. Compounds of Vamac® G are typically rated at 175°C (347°F) for heat resistance, with oil swell values around 50% in IRM 903 oil. These properties of Vamac® G make it well suited for a wide range of automotive applications, including powertrain seals and gaskets, rocker cover and piston seals, oil coolant hoses, power steering hoses, turbocharger hoses, crankcase ventilating tubes, coverings for fuel and coolant hoses, O-rings, grommets and spark plug boots. Vamac® G is an excellent vibration damping material that is uniquely insensitive to temperature over a range of -30°C (-22°F) to 160°C (320°F). Compounds of Vamac® G are suitable for use in torsional dampers and isolator pads.
DuPont™ Vamac® GLS is a terpolymer of ethylene, methylacrylate, and a curesite monomer cured using a diamine-based vulcanization system. Compared with Vamac® G, Vamac® GLS offers significantly improved resistance to oil swell and chemicals such as diesel fuel. Vamac® GLS elastomer contains a small amount of processing aid and has a nominal specific gravity of 1.06.
Vamac® GXF is a terpolymer of ethylene, methylacrylate, and a curesite monomer cured by and amine-based vulcanization system. Compared with Vamac® G, Vamac® GXF has improved high temperature properties and better dynamic flex fatigue resistance. Vamac® GXF includes a small amount of processing aid, has a nominal specific gravity of 1.03, and a mild acrylic odor.
Compounds of Vamac® GXF copared to Vamac® G have longer scorch time for improved processing and slightly higher compression sets. Elongation and properties at elevated temperatures are improved resulting in significantly improved dynamic flex-fatigue resistance, with similar heat and fluid aging resistance.
Vamac® HVG is a Vamac® G type polymer with a Mooney Viscosity of 26 compared to 16 for Vamac® G. The two polymers have similar compositions but the Vamac® HVG has a higher molecular weight. They have many common features, including processing advantages, such as:
Vamac® Ultra HT
Vamac® Ultra HT, formerly known as Vamac® VMX 3038, has been developed to extend heat resistance and the dynamic performance of the standard Vamac® portfolio to a temperature range of 170 -180 °C, suitable for demanding applications such as turbo hoses and air ducts.
Vamac® Ultra HT is a terpolymer of ethylene methyl acrylate (AEM) with an acidic cure site using a diamine-based vulcanization system delivering higher mechanical properties and better low temperature flexibility. Inherently, it has a halogen free structure like other Vamac® grades, all providing superior acid resistance (acid presents in blow-by gas, and exhaust gas recirculation).
The Vamac® Ultra family which includes Vamac® Ultra HT offers a specific polymer design with a higher viscosity improving process & properties versus standard Vamac® grades. Vamac® Ultra HT can be compounded as a DOTG free compound similar to other Vamac® terpolymer products.
Vamac® Ultra IP
Vamac® Ultra IP is an ethylene acrylate based polymer with an acidic curesite monomer. Compounds made from Vamac® Ultra IP have improved processing (IP) compared to Vamac® G and Vamac® GLS compounds. They also have better tear and high temperature physical properties, and improved long term aging. Compounds made from Vamac® Ultra IP have similar compression set, CSR, fluid resistance and low-temperature properties when compared to compounds made from Vamac® G.
Vamac® Ultra IP has a 30 Mooney viscosity so compounds made from Vamac® Ultra IP have a higher viscosity than compounds made from Vamac® G. This higher viscosity and improved processing provides compounds that are easier to injection mold, with less hot tear and mold cleaning issues.
Vamac® Ultra LT
Vamac® Ultra LT (formerly Vamac® VMX 4017) is an ethylene methyl acrylate based polymer with an acidic curesite monomer. It has improved low-temperature properties compared to both Vamac® G and Vamac® GLS. Compounds made from Vamac® Ultra LT also have similar heat resistance, compression set, CSR and dynamic properties when compared to compounds made from Vamac® G and GLS.
The Tg for Vamac® Ultra LT polymer is about 12°C lower than the the Tg for Vamac® G. A compound made from Vamac® Ultra LT with 20 phr of plasticizer has a Tg of -54°C. A compound without plasticizer has a Tg of -40°C.
Vamac® VMX-3110 is a developmental terpolymer of ethylene, methylacrylate, and a curesite monomer for curing with a diamine-based curing system. This polymer is designed to have high oil resistance like Vamac® GLS, and improved processability in the injection molding process like Vamac® Ultra IP.
The high viscosity of Vamac® VMX-3110 compared to Vamac® GLS also results in better mixing as well as increased green strength of compounds, and helps to avoid collapse during extrusion processes.
Vamac® is a registered trademark of E.I. Du Pont De Nemours and Company.
VAROX® Organic Peroxide
R.T. Vanderbilt Holding Company, Inc.
30 Winfield Street
Norwalk, CT 06856
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