The Effect of Thermal Ageing on the Fatigue Resistance of Hydrogenated Acrylonitrile Butadiene Rubber (HNBR) Compounds.

Compounds incorporating hydrogenated acrylonitrile butadiene rubber (HNBR) are widely adopted in applications that operate under extreme conditions such as at high temperatures, often whilst in contact with oil and other chemicals. They also work effectively when subjected to high strains and high strain rates. The detailed mechanisms that allow these materials to perform so well under these specific conditions are not yet fully understood. In this study a high acrylonitrile (ACN) content HNBR is incorporated into four different rubber compounds that are subjected to different thermal ageing conditions to investigate their impact on fatigue crack growth resistance of the cured compound. The resulting compounds are subjected to detailed DSC, TGA and FTIR analysis to help understand the changes that take place in the compounds during ageing for the first time. Counterintuitively, in this work ageing under specific set of conditions can produce an increase in the fatigue crack resistance in some of the elastomer compounds and when this happens it is observed that this occurs when the HNBR compounds develop knottier tearing profiles. Analysis of the DSC, FTIR and TGA results confirm that during ageing there is a steady evolution of the some of the ingredients in the compound such as the processing oils and the plasticiser which appears to have a significant effect on the fatigue properties of the HNBR materials. [ABSTRACT FROM AUTHOR]