Mechanical properties of rubber composites with cup-stacked carbon nanotubes

Cup-stacked carbon nanotubes (Cup-CNTs) consist of truncated conical graphene layers which exhibit open edges on the tube outer surface. Therefore, when used as filler, Cup-CNTs are expected to have many contact points with the matrix. Acrylonitrile butadiene rubber (NBR) composites containing Cup-CNTs were prepared by mixing the chloroform solutions of Cup-CNTs and NBR polymer followed by the evaporation of the solvent. Using this method Cup-CNTs were dispersed homogeneously in the NBR matrix. Cup-CNTs with different lengths (short- and middle-types) were used and the dependences of the mechanical properties on the length were investigated. The middle-type Cup-CNTs showed better reinforcing effects in terms of tensile strength, Young's modulus and hardness.