Influence of Thermo-Oxidative Ageing of HNBR in Oil Field Applications

摘要

The oxidative ageing behavior of carbon black- (85 phr) filled hydrogenated nitrile-butadiene rubber (HNBR) was characterized in this study. HNBR is widely used inmany oil and gas field applications for seals, hoses, down-hole packers etc., due to its intrinsic combination of good heat and excellent oil and chemical resistance, coupled with outstanding physical properties. Hence, to support the material development, it is of prime theoretical and practical importance to characterize the ageing behavior of HNBR. In this work, mechanical properties and dynamic mechanical properties of aged and un-aged material were examined using tensile, tear and dynamic mechanical analysis tests. Possible micro structural changes and functional groups involved in aging were detected using DQ NMR, Raman spectroscopy and FT-IR spectroscopy in ATR mode. The results indicated that the ageing process caused the material to deteriorate; tensile strength - strain at break, the strain at tear strength and the damping properties were decreased. Additionally, the stiffness and the glass transition temperature of the material were also raised. According to the literature, residual double bonds in HNBR are involved in forming hydro peroxide and propagating the autocatalytic oxidation process in the presence of oxygen at higher temperature. This process leads to the oxidative degradation resulting in cross-linking and in chain scissions as the predominant reactions contributing to properties. Furthermore, at ～100 °C, oxidation through the nitrile group was observed converting the cyano functional group into the imino group; but at higher temperatures, it was negligible. The results suggest that the cross-linking and the chain scissionmechanisms are significant after 72 hours and 168 hours of exposure, respectively, at 150 °C. However, when aged at 170 °C, both cross- linking and chain scission were even effective after 24 hours of exposure time.