Thermoplastic moulding of wood-polymer composites (WPC): a review and research proposal on thermo-physical and geometric design options using hot-pressing

Wood-plastic composites (WPC) can incorporate up to 80% wood fibres, which reduces the use of scarce oil resources for plastic production. To increase the interest of industrial deciders in applying WPCs in the building sector, for example in façades, application-oriented basic research on thermoplastic shaping after hot-pressing of already produced sheets is necessary. This review paper reports on a comprehensive analysis of the current state of research on basic temperature-related WPC properties such as thermal conductivity, heat storage capacity and thermal expansion. In addition, it discusses geometric material specifications, which play a role when WPC sheets become thermoformed and sculptured for three-dimensional façade applications. It is demonstrated that WPCs offer interesting potential to positively regulate the interior climate of a building, and that other components, such as phase change materials (PCM), can be effectively combined with this biobased composite. In terms of geometric design options there is still a lack of research about minimum bending radii and potential shape memory effects of WPCs after re-heating and cooling. Finally, this paper provides recommendations on which experimental studies are necessary to close these research gaps and which hypotheses are to be tested. With the knowledge to be generated, a successful development of three-dimensional WPC products in industrial mass production becomes feasible.