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Next Generation of Heat Resistant Acrylic Rubbers
In the early 21st century, we introduced a new high temperature ACM type family (HT-ACM’s) with significantly improved heat resistance compared to existing acrylate polymer grades. Those developments opened the scope of applications to longer lifetimes i.e. in ACM head cover gaskets or other sealings e.g. O-rings or precision molded parts and also in the application area of turbo charger hose and transmission oil cooler hose.
The continuing trend for super charged engines, as a tribute to better fuel economy, along with smaller engine compartments and encapsulation of the engine block added new requirements to elastomeric parts under the hood up to 190°C where 150°C had been sufficient before or, otherwise, high cost FKM and VMQ needed to be used.
Unimatec´s technology closed this new temperature gap between ACM and FKM with the newly developed HT-ACM types. This generation of HT-ACM became superior in heat-resistance up to 190°C.
This paper highlights further developments in the area of dynamic durability improvement. For a number of new applications HT-ACM requires enhanced tensile and tear strength along with elongation after heat aging. ACM by chemical nature shows two types of heat stress.
One is heat softening, the other one is hardening. Heat softening degradation is characterized by stable elongation and deteriorated tensile strength properties. During heat hardening tensile strength is stable but elongation is decreased. A new type of high durability HT-ACM was developed which was designed to feature optimized properties of mechanical performance like tensile strength, tear resistance and elongation without sacrificing any of the other strengths of the polymer structure.