Effect of Immersion Fluid Changes on Essential Properties of Common Static Sealing Rubbers
ABSTRACT
Knowing the behavior of rubber when exposed to a fluid or fluid-like medium is very important when establishing the suitability of a rubber material as a sealing element. Classical ASTM D471 immersion testing remains the standard evaluation protocol and specifies that the rubber material be immersed in a defined volume of fluid for a specified amount of time at a constant temperature. The medium is not changed during the test period. However, for other suitability determining tests, such as compression stress relaxation, the medium is exchanged with fresh at prescribed intervals, typically every 336 hours. The effects of adding fresh fluid during the test on the rubber sample can be significant compared to the so-called constant immersion condition whereby the fluid is thermally aging along with the rubber. This investigation compares the effects of changing the immersion fluids on the rubber material. Seven materials will be examined against two common automotive fluids.