ترکیبات لاستیک هیدروژنه نیتریل بوتادین
Abstract
1-Introduction
2-Experimental method and materials
3-Results and discussion
4-Conclusions and perspectives
Appendix A. Uniaxial tension results
References
Abstract
HNBR (Hydrogenated Nitrile Butadiene Rubber) is a synthetic rubber with good resistance to heat and oil products; due its properties, HNBR is utilized in high-demanding applications in oil exploration, aerospace, automotive, and other industries. However, compared to other industrial rubbers, there are only few published studies on the fatigue behavior of HNBR. Moreover, it is important to understand how fatigue resistance is affected by the formulation of HNBR, specifically by the content of acrylonitrile (ACN) monomers and percentage of hydrogenation (number of saturated bonds). First, fatigue experiments are carried out for unaged samples at 120°C, which is the median operating temperature for these HNBR blends. Five HNBR blends are tested with various contents of acrylonitrile and various percentages of hydrogenation. Afterwards, testing is carried out one of the blend, i.e. HNBR with 36% ACN and 96% hydrogenation at 150°C for simultaneous ageing and fatigue conditions. For fatigue life experiments, the Wöhler curve is built according to a novel experimental approach of true stress control for four loading levels and R=0 loading ratio. Preliminary results with thermal ageing are subsequently presented.
Introduction
Various rubbers have been in use for well over a century. The versatility of rubber materials is attributed to their ability to withstand large strain in mostly elastic manner. Rubber is used for a wide variety of parts (such as tires, hoses, seals, etc.) and in many industries (automotive, aerospace, civil, energy, etc.). HNBR (Hydrogenated Nitrile Butadiene Rubber) is a synthetic rubber with good resistance to heat and oil products. Due to its properties, HNBR is utilized in high-demanding applications in oil exploration, aerospace, automotive, and other industries [1]. Additionally, HNBR has relatively good mechanical properties. Improvement of the characteristics of NBR blends in terms of heat, chemical and environmental resistance, and abrasion is achieved by high saturation level of the HNBR, where the double carbon-carbon bonds in the polymer chain are removed by a selective hydrogenation reaction [2]. In simple terms, HNBR is made out of saturated and unsaturated butadiene and acrylonitrile (ACN) monomers [3]. In general, increasing ACN content leads to a better chemical resistance (fuels, solvents, etc.) and increasing the percentage of hydrogenation (amount of saturated C-C bonds) to a better heat resistance [2], [4], [5].