Investigation on the dispersion of carbon nanotubes in nitrile butadiene rubber: Role of polymer-to-filler grafting reaction

This contribution reports on the dispersion by simple melt blending of tiny amounts of carbon nanotubes (CNT) in nitrile butadiene rubbers (NBR). Acrylonitrile (ACN) units of NBR are known to generate free radicals upon heating and/or shearing. This paper highlights elements evidencing a possibility for NBR polymer chains to react by a free-radical mechanism and to graft onto CNT surface all along the process of mechanical blending of NBR with CNTs. More precisely and since the formation of the free-radicals takes place on the ACN units, the influence of the ACN relative content in NBR on the grafted CNT amount has been studied. It comes out that the polymer-grafting rate onto the CNT surface increases with the ACN content in NBR. Interestingly, the nanotubes proved more finely dispersed in NBR containing higher relative ACN content as evidenced by morphological observations as well as electrical measurements.