Role of rheology in tunning thermal conductivity of polyamide 12/polyamide 6 composites with a segregated multiwalled carbon nanotube network

Abstract

Effect of multiwalled carbon nanotubes in thermal conductivity of an immiscible blend of polyamides, 50/50 (wt%/wt%) polyamide 12/polyamide 6, was analyzed as function of nanofiller amount and temperature. Effect of the molding temperature in the structure of conductive network was investigated by rheology.

Data show that 5 vol% multiwalled carbon nanotubes caused an increase of 41% in thermal diffusivity and 78% in thermal conductivity respect to polyamide blend values. Thermal conductivity improvement could be described by percolation theory, with a low threshold composition (φ_c = 0.09 vol% carbon nanotube). Fitting parameters obtained from Agari’s adjustment model show that polyamides structure is not affected by carbon nanotubes and the nanofillers can easily form conductive paths in the polyamide 12/polyamide 6 matrix.

The temperature increase facilitates nanofiller dispersion causing the formation of a denser carbon nanotube network and rising the thermal diffusivity of carbon nanotube composites with low percolation level, as was proved on annealed samples at 255℃.