Sustainable rubber nanocomposites for hydrogen sealings: Impact of carbon nano-onions and bio-based plasticizer

Additives play a crucial role in modifying and enhancing the properties of rubbers, improving mechanical strength, thermal stability, and chemical resistance to make them more suitable for various applications. The rubber industry faces challenges related to high resource consumption and toxic emissions, which are further impacted by the use of performance-enhancing additives. In hydrogen storage systems, tailored additives are required for rubbers to withstand elevated temperatures and high pressures, preventing hydrogen-induced swelling, a major cause of sealing failure. Herein, a novel form of carbonaceous material, carbon nano-onions (CNOs), and the bio-based plasticizer additive epoxidized soybean oil (ESO) are utilized in conventional silica-filled nitrile butadiene rubber (NBR) nanocomposites to develop low-carbon manufacturing high pressure hydrogen resistant O-rings for sealing applications. The results reveal that the incorporation of CNOs increases the crosslinking density (v_c), assisted by ESO, in silica-filled NBR nanocomposites. While the conventional adipate-based plasticizer and ESO were found to be susceptible to high pressure hydrogen exposures, ESO demonstrated sustained compressive sealing properties with increase in von-Mises stress and in elevated thermo-oxidative conditions over time. The results of the life cycle assessment (LCA) recommend ESO for low-carbon manufacturing in rubber processing over conventional plasticizer.