Hybridisation effect of carboxyl graphene and silica nanofillers on environmentally aged composite acrylonitrile butadiene rubber

Filler hybridisation in elastomers has become a subject of both scientific and industrial interest. Consequently, the use of nanofillers has attracted researchers looking to enhance the performance of elastomers. Therefore, carboxyl graphene (CG) and silicon dioxide (SiO₂) nanofillers have been hybridised for the combined effect study of composite NBR (acrylonitrile butadiene rubber) elastomers in various accelerated environmental ageing conditions (high temperature, low temperature, and QUV). The inorganic filler (SiO₂) had enhanced dispersion upon hybridising with CG on the surface of a composite NBR elastomer. To evaluate the mechanical and dynamic mechanical properties, unfilled and filled (CG/SiO₂) composite NBR elastomer samples were prepared by mixing and rolling methods. Furthermore, the prepared samples were kept in various ageing chambers. The results of mechanical testing exhibited that tensile strength improvement was greater for filled elastomers than unfilled elastomers after ageing. Moreover, the filled elastomers were also able to retain the reduction in elongation at break after ageing. However, after ageing, the hardness of composite NBR elastomers increased marginally with the addition of CG/SiO₂. Moreover, the loss factor (tan δ) of a composite NBR elastomer (CG/SiO₂: 15/7.5), compared to that of the unfilled NBR elastomer before and after ageing, decreased but was still much higher than that of the aged unfilled NBR elastomer. The reason behind that was that CG/SiO₂ dispersion in the composite NBR elastomer matrix acted as a barrier against ageing. CG/SiO₂ hybridising is an effective way to develop high-performance composite NBR elastomers with good potential in industrial applications.

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