Effects of elevated temperature and crude oil on the properties of a hydrogenated nitrile butadiene rubber elastomer

The stability and durability of hydrogenated nitrile butadiene rubber (HNBR) material in crude oil environments are of great importance for petroleum equipment to resist leakage and to ensure reliability. In this paper, an HNBR material was fabricated, and the degradation of the HNBR material was investigated in simulated crude oil environments. One crude oil and three temperatures (50 degrees C, 75 degrees C, and 100 degrees C, based on actual crude oil operations, were used in this study. Weight changes for the HNBR specimens were monitored after exposure to the environments over time. Optical microscopy was used to show the topographical changes on the specimen surfaces. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was employed to study the surface chemistry of the HNBR material before and after exposure to the simulated crude oil environments at selected times. Mechanical property tests (tensile and compressive stress-strain tests, tear strength test, and compression set test) were conducted to assess the changes in mechanical properties of the HNBR specimens before and after exposure to the environments. The test results show that the physical-mechanical properties of the HNBR material changed significantly. The temperature and the crude oil had a direct effect on the degradation of the mechanical properties. The ATR-FTIR test results indicate that the surface chemistry changed via chain crosslinking in the material after exposure to the environments over time. The degradation mechanisms of the HNBR material after exposure to the crude oil could be due to the presence of chain crosslinking, chain mobility, and backbone scission. (C) 2016 Wiley Periodicals, Inc.