The dispersion of carbon nanotubes in polymer composites is a major challenge. Although nanotubes have a high aspect ratio, their tendency to agglomerate limit percolation at low loading. We find that thermal diffusion is reducing agglomeration considerably and we show that uniform dispersions can be formed when using multiwall carbon nanotubes. It is very unusual that agglomerated tubes disperse spontaneously in a highly viscous thermoplastic polymer. We attribute the thermal diffusion induced dispersion to the strong contrast in the dielectric properties of the nanotubes and the polymer matrix. Strong absorption of the nanotubes in the near infrared spectral region leads to selective heating of the nanotubes. We find that the formation of a temperature gradient between the nanotubes and polymer matrix induces preferential diffusion along the tube axis and Brownian motion of the tubes contributes in addition to efficiently disperse carbon nanotubes in a viscous thermoplastic polymer. We will present transmission electron microscopy, Raman spectral maps and insitu optical microscopy studies showing the formation of a diffusion layer using single, double and multiwall carbon nanotubes.
Journal: TechConnect Briefs
Volume: 1, Nanotechnology 2012: Advanced Materials, CNTs, Particles, Films and Composites (Volume 1)
Published: June 18, 2012
Pages: 298 - 301
Industry sector: Advanced Materials & Manufacturing
Topics: Carbon Nano Structures & Devices