Mechanical and tribological performance of acrylonitrile-butadiene rubber/carbon black/cryptocrystalline graphite composites

In this study, cryptocrystalline graphite (CG) was investigated as a novel functional filler for acrylonitrile-butadiene rubber (NBR)/carbon black (CB) composites. NBR/CB/CG composites are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) as well as differential scanning calorimetry (DSC). The results showed that NBR/CB/CG-10 increased by 18.2%, 11.0%, and 10.0% in tensile strength, 300% tensile modulus and tear strength, respectively compared with NBR/CB. Uniform filler dispersion and stronger interfacial interaction contributed to enhancing the mechanical property of NBR/CB/CG composites. It was revealed that the small particle size, rough surface, and defective structure of CG facilitated its exfoliation and intercalation. In addition, the tribological performance of NBR/CB/CG composites was tested on a ring-on-block wear tester under dry sliding conditions. The friction coefficient and specific wear rate of NBR/CB/CG-5 reduced by 50.3% and 51.4%, respectively through the formation of fine lubrication and transfer films. CG enhanced the thermal stability, mechanical, and tribological performance of NBR composites simultaneously and the results of this work proved that CG would be a cost-effective and resource-available functional filler especially suitable for rubber seal application.