Effect of carbon nanofibers on mechanical and electrical behaviors of acrylonitrile-butadiene rubber composites

Recently, carbon nanofibers have become an innovative reinforcing filler that has drawn increased attention from researchers. In this work, the reinforcement of acrylonitrile butadiene rubber (NBR) with carbon nanofibers (CNFs) was studied to determine the potential of carbon nanofibers as reinforcing filler in rubber technology. Furthermore, the performance of NBR compounds filled with carbon nanofibers was compared with the composites containing carbon black characterized by spherical particle type. Filler dispersion in elastomer matrix plays an essential role in polymer reinforcement, so we also analyzed the influence of dispersing agents on the performance of NBR composites. We applied several types of dispersing agents: anionic, cationic, nonionic, and ionic liquids. The fillers were characterized by dibutylphtalate absorption analysis, aggregate size, and rheological properties of filler suspensions. The vulcanization kinetics of rubber compounds, crosslink density, mechanical properties, hysteresis, and conductive properties of vulcanizates were also investigated. Moreover, scanning electron microscopy images were used to determine the filler dispersion in the elastomer matrix. The incorporation of the carbon nanofibers has a superior influence on the tensile strength of NBR compared with the samples containing carbon black. It was observed that addition of studied dispersing agents affected the performance of NBR/CNF and NBR/carbon black materials. Especially, the application of nonylphenyl poly(ethylene glycol) ether and 1-butyl-3-methylimidazolium tetrafluoroborate contributed to enhanced mechanical properties and electrical conductivity of NBR/CNF composites.