19 April 2021

Polyacrylic Rubbers (ACM, AEM)

Acrylic rubbers (ACM, AEM) are obtained by radical polymerization in emulsion of acrylic unsaturated esters and ethers, adding diene unconjugated monomers as crosslink locations. In the molecular chain of acrylic rubbers, when the ethyl acrylate content increases, high temperatures and oil resistances improve. As butyl acrylate increases, resistance to low temperatures resistance improves.

A combination of ethyl acrylate, butyl acrylate and alkoxy acrylate produces different balances between the two characteristics mentioned above.  Containing Since they contain a chlorinated co-monomer as vulcanization site, they vulcanize by addition of diamine, thiourea derivatives or polyamide compounds. To improve physical and mechanical characteristics, and to have a lower compression set, a post vulcanization cycle is always necessary.

Acrylic rubbers are mainly used when combined heat and oil resistance is are required.

They are often a possible alternative to more expensive elastomers, such as fluorocarbon polymers (FKM), silicones (VMQ) and fluororosilicones (FVMQ) for high temperature applications.

The most important features of these elastomers are the excellent resistance to aliphatic oils, oxygen, ozone, atmospheric agents, as well as the abovementioned excellent resistance to high temperatures and ageing in general.

Mediocre mechanical properties and poor elasticity are considered to be the main disadvantages.

Typical applications include automotive transmission components such as gaskets and flexible pipes that must withstand high-temperature oil, fuel and many other common automotive lubricants and hydraulic fluids. Acrylic rubbers are also used in vibration dampening, thanks to their excellent resilience. Other applications include textiles, adhesives and coatings.