Press Cure and Post Cure Options for AEM Terpolymers

Compounds made from AEM (Vamac® ethylene acrylic elastomers) terpolymers have good heat resistance due in part to the cure system which permits reaction to take place in two stages. In a commercial molding process, the initial cure step occurs in the press and the second step takes place in the post cure oven. For an extruded hose, the initial cure step is in the autoclave and the second step occurs either in the autoclave (depends on time/temperature) or in the post cure oven. There are several important issues related to molding operations which will be addressed in this paper including:
• How changes in the press cure step affect post cured properties. Studies were
conducted of compounds that were press cured at different conditions and then
post cured. These compounds had similar properties after post cure which implies
that a decrease in cycle time may not affect finished properties.
• Whether the post cure step can be eliminated via a combination of improved
molding conditions and formulation changes. The most aggressive compounds
and conditions studied did not meet the targets without a post cure step.
• Whether the length of time needed for post cure, typically four hours, can be
reduced. In a lab environment the time can be reduced and the compression set
targets can still be met.