Molecular Dynamics Study on the Thermal Conductivity of the End-grafted Carbon Nanotubes Filled Polyamide-6.6 Nanocomposites

2017-12-26T00:00:00Z (GMT) by Yangyang Gao Florian Müller-Plathe
It is very important to improve the thermal conductivity of polymer nanocomposites to widen their application. In this work, the effect of grafted chains and mechanical deformation on the thermal conductivity of end-grafted carbon nanotubes (CNTs) filled polyamide-6.6 nanocomposites has been investigated by molecular dynamics simulation. The results show that the thermal conductivity increases with the grafting density, while it first increases and then saturates with the length of the grafted chains. The dependence of the thermal conductivity on the density and the length of the grafted chains is described by an empirical equation. Moreover, it is further improved if all CNTs are linked by chains or CNTs align along one direction, especially the latter. By fitting the present simulation results with an effective medium approximation model, interfacial thermal resistance is obtained, which indicates that a stronger enhancement of the thermal conductivity is realized when chains are grafted at the end atoms of CNTs. Under deformation, the orientation of both the chains and the CNTs improves the thermal conductivity parallel to the tensile direction, but reduces the thermal conductivity perpendicular to it. Finally, the contribution of the polymer alignment and the CNT alignment to the anisotropy of thermal conductivity is quantified.