Dispersion and distribution of carbon nanotubes in ternary rubber blends

Structure and morphology of carbon nanotubes (CNTs) filled ternary styrene butadiene rubber (SBR)/nitrile butadiene rubber (NBR)/natural rubber (NR) blends were characterized quantitatively by means of the wetting concept und qualitatively supported by transmission electron microscopy (TEM) and atomic force microscopy (AFM). It was found that CNTs mainly reside in the polar NBR and non-polar NR but not in weak polar SBR. Such unusual localization of CNTs in ternary SBR/NBR/NR can be explained by taking into consideration the presence of phospholipids in NR. Phospholipid can act as coupling agent bonding the α-terminal of NR with the CNT surface through cation-π interactions, which make NR be competitive with NBR with respect to CNT hosting. Setting the equilibrium CNT loadings experimentally determined by the wetting concept into the Z-model recently developed in our previous work by keeping unchanged the surface tension values of SBR and NBR a corrected value of surface tension of NR was determined, which involves the effect of phospholipids.