Zinc oxide nanorod-based elastomeric composites with enhanced oil resistance and flex crack resistance for oil seal applications

Abstract

Oil seals, widely used in hydraulic systems, pump connections, and pistons, should offer durability, high sealing performance, and exhibit a self-lubricating effect. These seals are typically made from lightweight materials that resist hardening or softening during their service life. Acrylonitrile butadiene rubber (NBR) is the most commonly employed elastomer in oil seals manufacturing due to its excellent resistance to petroleum-based oils. Additionally, NBR-based products exhibit notable flex crack resistance. The judicious incorporation of nanofillers at lower loadings, rather than high quantities of conventional fillers, can further enhance performance while retaining the lightweight nature. In this work, zinc oxide nanorods (ZNR) were synthesised and incorporated into NBR to achieve multiple advantages in cure characteristics, mechanical properties, crosslink density, dynamic mechanical properties, oil resistance, and flex crack resistance. Remarkably, all these improvements could be achieved using only half the amount of conventional zinc oxide typically used in NBR formulations. This approach not only preserves material performance but also mitigates the harmful effects of zinc contamination from rubber products on humans, animals, and aquatic life. Furthermore, the role of nano zinc oxide on NBR-carbon black composites was systematically evaluated and compared with conventional NBR-carbon black composites with twice the zinc oxide loading, confirming the superior efficiency of ZNR.