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Multiwalled carbon nanotubes decorated with nanosilica particles (CS hybrids) were prepared for the first time by ultrasonication assisted mixing of the aqueous dispersions of carboxylated multiwalled carbon nanotubes (MWCNTRs) and colloidal nanosilica. The natural rubber (NR) nanocomposite (NRCSF) was prepared with CS hybrid filler by latex stage mixing method. The SEM and TEM images and strain sweep studies confirmed the formation of segregated network structure inside the nanocomposite due to the alignment of hybrid fillers along the periphery of NR latex spheres. The NRCSF composite exhibited excellent mechanical properties and solvent barrier properties. The NRCSF composites displayed high dielectric constant and low electrical percolation threshold (0.80 vol%). The composite exhibited low dielectric loss because of the presence of insulating nanosilica particles around conducting carbon nanotubes. These elastomeric nanocomposites with high k and low loss are promising in the field of dielectric elastomers for actuator applications.

In the present study Vulcastab VL (polyethylene oxide condensate) has been used as a non-ionic surfactant to get stable aqueous dispersions of multiwalled carbon nanotubes (MWCNTs). Sonication time and surfactant concentration were optimised by UV-vis spectroscopy and dynamic light scattering technique. Homogeneously dispersed surfactant coated individual MWCNTs in water were clearly evident from Transmission electron microscopy (TEM). Natural rubber –Multiwalled carbon nanotube (NR-MWCNT) nanocomposites were prepared by latex stage mixing. Instead of being randomly dispersed, MWCNTs were found to retain at the boundary of rubber particles resulting in a segregated network as evidenced from TEM. Addition of very small amount of MWCNT showed remarkable improvement in mechanical, thermal, electrical and barrier properties of NR. Segregated network of CNTs resulted in very low electrical percolation threshold (0.043 vol%) for the composite with enhanced dielectric properties.