Increased through-plane thermal conductivity of injection moulded thermoplastic composites by manipulation of filler orientation

This paper aims to increase the through-plane thermal conductivity of polymer composites by adjusting the filler orientation. Two methods were tested: a combination of immiscible polymers (PP-PET) and adding a foaming agent to a PA6-based composite. In both cases, graphite was used as a thermal conductive filler. Compounds with 10, 20 and 30 wt-% graphite were made for both methods. The through-plane thermal conductivity increased for all PA6- foaming agent composites, while the in-plane thermal conductivity decreased compared to PA6 without foaming agent. PP-PET combinations generally outperformed the PP in through-plane performances as well. Tensile strength decreased with increasing amounts of graphite. As expected, adding foaming agents and a second phase decreased strength as well compared with virgin materials. With further optimisation, a combination of fillers and foaming agents in thermoplastics or two-phase systems could prove to be valuable in thermal management applications.