Polymer Compounds with High Thermal Conductivity

The thermal conductivity of commercially available thermally conductive polymer-compounds is usually between 1 W/mK and 20 W/mK what means that they are already 10 to 100 times higher than the conventional unfilled polymer. During the development at ZBT the values for thermal conductivity of polymer-compounds could be increased to more than 30 W/mK. In order to achieve such conductivities, the compound materials generally consist of a polymer, which functions as a binding matrix, and a high content (up to 80 wt.%) of conductive filler material. In various series of investigations the thermal conductivity but also the mechanical properties and the processing by extrusion and injection molding of the highly filled materials were evaluated. An orientation of filler particles by injection molding could be observed. Images by scanning-electron-microscopy of injection molded samples showed a structure of anisotropic layers which has a significant influence on the values of thermal conductivity. That's why a differentiation of "through-plane" and "in-plane" thermal conductivity is highly recommended.