Low percolation threshold of functionalized single-walled carbon nanotubes-polycarbonate nanocomposites

Abstract

A series of polycarbonate films loaded with different concentrations of UV-ozone pretreated single-walled carbon nanotubes were prepared. The electrical and mechanical properties of these composites were investigated. The improvement of the single-walled carbon nanotubes dispersion in polycarbonate (PC) matrix leads to a dramatic enhancement in the electrical conductivity with low percolation threshold (0.5 wt% of single-walled carbon nanotubes loading). Results obtained from the analysis of the dielectric parameters at room temperature and domain frequency range reveal that single-walled carbon nanotubes increases the dielectric constant, dielectric loss, and AC conductivity of the composites. The dielectric relaxation behavior of these composites is mostly due to polymer molecular relaxation when the single-walled carbon nanotubes content is below the percolation threshold whereas it is almost due to the charge conductivity relaxation above 0.8 wt% single-walled carbon nanotubes. The calculated values of the elastic modulus obtained from the stress-strain curves also show a percolation behavior with a threshold of 0.08 wt% single-walled carbon nanotube. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.