Effective thermal conductivity of epoxy matrix filled with poly(ethyleneimine) functionalized carbon nanotubes

Considering that amine group can react with epoxy resin, poly(ethyleneimine) (PEI) functionalized carbon nanotubes (CNTs) have been used to fabricate CNT/epoxy matrix composite for the potential of thermal performance improvement. The functionalization of CNTs, the dispersion of CNTs in epoxy matrix, and the effective thermal conductivity of the composites have been characterized by thermal gravimetric analysis (TGA), scanning electron microscope (SEM), and thermal analyzer, respectively. The PEI functionalized CNTs show better dispersion in epoxy matrix and higher thermal conductivity under the same volume fraction, compared to the non-functionalized ones, which means that PEI molecule is a good bridge between CNTs and epoxy. And from a proper model, the calculated results confirm that PEI functionalization on CNTs can not only reduce the interface thermal resistance, but also improve the dispersion of CNTs in the epoxy, both of which would contribute to the enhancement of thermal conductivity. A 660% enhancement in thermal conductivity can be achieved in the CNT/epoxy matrix composite when the PEI functionalized CNTs’ loading is as high as 8 vol.%.