Influence on thermal conductivity of polyamide-6 covalently-grafted graphene nanocomposites: varied grafting-structures by controllable macromolecular length

The influence of the grafting-structures of different length polymer chains on the thermal conductive properties of polyamide-6/graphene (PG) nanocomposites are studied. The in situ thermal polycondensation method was used to realize length-controllable polyamide-6 (PA6) chains covalently grafted onto reduced graphene oxide (RGO) sheets, in which the content of graphene oxide was fixed and the thermal reduction of RGO was kept at a similar level. The experimental results show that the thermal conductivity (lambda) of the PG nanocomposites decreases with the increasing length of the grafted PA6 chains (1.8 to 7.4 nm) from 0.293 to 0.265 W m(-1) K-1. This result is in good agreement with previous simulation work and demonstrates that shorter PA6 chains are more effective in reducing the interface thermal resistance and improving the lambda of the PG nanocomposites, which will promote research aimed at reducing the significant interface thermal resistance between the graphene and the polymer matrix to effectively improve the l of thermal conductive materials.