Reinforcement of acrylonitrile butadiene rubber using pristine few layer graphene and its hybrid fillers

Unfunctionalized few layer graphene (FLG) nanoplatelets were mixed with acrylonitrile butadiene rubber (NBR) by melt mixing and the properties were compared with composites containing carbon black alone and a 1:1 mixture of FLG and carbon black. Incorporation of a very small amount of FLG significantly improved the cure characteristics of NBR. Compared to graphene, similar loading of carbon black gave higher rheometer torque at the expense of scorch safety whereas hybrid filler gave optimum cure characteristics. There was more than 190% improvement in tensile strength when 5 phr FLG was added to the matrix. On the other hand, to achieve the same strength, five times more of carbon black was needed compared to FLG. In contrast to carbon black, FLG increased the compression set of the rubber. The compositions containing 1:1 mixture of the fillers displayed compression set values in between those containing FLG or carbon black alone. The storage modulus was also found to be optimum for the composites containing equal amounts of FLG and carbon black. FLG loaded composites displayed significant reduction in the creep compliance. Additionally, the helium leak rate of the composites was decreased in presence of FLG due to its platelet structure. (C) 2013 Elsevier Ltd. All rights reserved.