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This work reports a statistical study on the relationship between the chemical-physical properties of CNTs, which vary by changing the conditions of purification and plasma treatment, and the macroscopic properties of PC-based nanocomposites. CNTs are synthesized and then purified in two different ways and used as fillers for the preparation of PC/CNTs nanocomposites. In some cases, oxygen plasma treatment is carried out to improve their affinity to the matrix. The CNTs are characterized by TGA, ICP/OES and FT-Raman spectroscopy, titration and morphological analysis. Mechanical, dynamic-mechanical, electrical and morphological tests are used for characterizing PC/CNTs nanocomposites.

The dispersibility of unfunctionalized multi-walled carbon nanotubes in a polymer matrix is studied focusing on the role of the morphology and structure of the primary aggregates. The particles, synthesized by fluidized bed catalytic chemical vapor deposition and purified through a scalable one-pot method, are dispersed in polystyrene by melt mixing. The filler percolation threshold, assessed through rheological analyses and dielectric spectroscopy, is one order of magnitude lower than that of commercially available nanotubes with similar features. This is ascribed to the hierarchical structure of the primary aggregates, which facilitates both the infiltration of the polymer in the earlier stages of mixing and the pulling out of the nanotubes required for their individualization. The high dispersibility is not achieved to the detriment of the nanotube integrity, and the nanocomposites exhibit enhanced thermal stability and dynamic mechanical properties at low amounts of filler.