Concerning the still rising demand for oil and gas products, the development of new reliable materials to guarantee the facility safety at extreme operating conditions is an utmost necessity. The present study mainly deals with the influence of different carbon black (CB) filled hydrogenated nitrile butadiene rubber (HNBR), which is a material usually used in sealing applications, on the rapid gas decompression (RGD) resistance in harsh environments. Therefore, RGD component level tests were conducted in an autoclave. The supporting mechanical and dynamic mechanical property analysis, the microscopic level investigations on the material and failure analysis were conducted and are discussed in this work. Under the tested conditions, the samples filled with smaller CB primary particles showed a slightly lower volume increase during the compression and decompression phases; however, they steered to a significantly lower resistance to RGD. Transmission electron micrographs revealed that the samples filled with smaller CB particles formed larger structures as well as densified filler networks including larger agglomerates and as a consequence a decrease effective matrix component around the CB particles. Apparently, at higher loading conditions, which already deliver a certain level of mechanical stresses and strains, the densified filler network, and especially a lower amount of effective matrix material composition, adversely affect the RGD resistance. SEM-based fracture analysis did not identify any influence of the CB grades tested on the crack initiation site; however, it revealed that the cracks initiated from existing voids, hard particles, or low strength matrix sites and propagated to the outer surface.

Typically, polymeric materials experience material degradation and damage over time in harsh environments. Improved understanding of the physical and chemical processes associated with possible damage modes intended in high-pressure hydrogen gas exposed atmospheres will help to select and develop materials well suited for applications fulfilling future energy demands in hydrogen as an energy carrier. In high-pressure hydrogen gas exposure conditions, damage from rapid gas decompression (RGD) and from aging in elastomeric as well as thermoplastic material components is unavoidable. This review discusses the applications of polymeric materials in a multi-material approach in the realization of the "Hydrogen economy". It covers the limitations of existing polymeric components, the current knowledge on polymeric material testing and characterization, and the latest developments. Some improvements are suggested in terms of material development and testing procedures to fill in the gaps in existing knowledge in the literature.

Summary The oxidative ageing behavior of carbon black‐ (85 phr) filled hydrogenated nitrile‐butadiene rubber (HNBR) was characterized in this study. HNBR is widely used in many 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 scission mechanisms 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.

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The ultimate properties and resistance to fracture of nanocomposites based on poly(1,4-cis-isoprene) from Hevea Brasiliensis (natural rubber, NR) and a high surface area nanosized graphite (HSAG) were improved by using HSAG functionalized with 2-(2,5-dimethyl-1H-pyrrol-1-yl)propane-1,3-diol (serinol pyrrole) (HSAG-SP). The functionalization reaction occurred through a domino process, by simply mixing HSAG and serinol pyrrole and heating at 180 °C. The polarity of HSAG-SP allowed its dispersion in NR latex and the isolation of NR/HSAG-SP masterbatches via coagulation. Nanocomposites, based either on pristine HSAG or on HSAG-SP, were prepared through traditional melt blending and cured with a sulphur-based system. The samples containing HSAG-SP revealed ultimate dispersion of the graphitic filler with smaller aggregates and higher amounts of few layers stacks and isolated layers, as revealed by transmission electron microscopy. With HSAG-SP, better stress and elongation at break and higher fracture resistance were obtained. Indeed, in the case of HSAG-SP-based composites, fracture occurred at larger deformation and with higher values of load and, at the highest filler content (24 phr), deviation of fracture propagation was observed. These results have been obtained with a moderate functionalization of the graphene layers (about 5%) and normal lab facilities. This work reveals a simple and scalable way to prepare tougher NR-based nanocomposites and indicates that the dispersion of a graphitic material in a rubber matrix can be improved without using an extra-amount of mechanical energy, just by modifying the chemical nature of the graphitic material through a sustainable process, avoiding the traditional complex approach, which implies oxidation to graphite oxide and subsequent partial reduction.