Influence of the curing state on the fatigue behavior of nitrile butadiene rubber

Elastomeric materials are often used as components that are exposed to cyclic loading during their application, such as tires, seals or hoses. For this reason, the long time performance, more precisely the crack growth behavior, is of great importance. Although many studies have addressed this issue over the last 80 years, it is still a widely discussed topic and remains of great interest among researchers. An enormous influence on the fatigue behavior is the state of cure of the rubber product. Previous literature assumes an increase in crack growth rate with increasing heating time and an optimum crosslink density for fatigue behavior. However, there are still gaps in the literature in this subject area. For this reason, a further analysis of these factors was apparent. Therefore, pure shear test specimens made of nitrile butadiene rubber (NBR) were produced by injection molding at different temperatures and heating times, and their influence on the crack growth behavior was determined. From these experiments, it was shown that an increase in the state of cure leads up to 100 times larger crack growth rate. With elevated heating times, a plateau is established. It is noteworthy that this plateau is at a lower level for higher temperatures.