Basic investigations into new wood-plastic composites with targeted fibre orientation and compression during layer-by-layer additive manufacturing

• Applicant: Professor Dr.-Ing. Florian Puch
• Subject Area: Plastics Engineering ; Polymeric and Biogenic Materials and Derived Composites
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 578768065

Wood-based materials are an interesting group of materials due to their CO2 storage effect (one m³ of wood binds one ton of CO2) and their suitability for substituting non-renewable raw materials. Conventional wood-based materials have not yet achieved the properties required for use in mechanically demanding parts. To increase the existing material potential, wood-based materials can be combined with plastics to form wood-plastic-composites (WPC). In the research project, a new class of WPC is being fundamentally investigated and developed, which is based on the layered structure and targeted compression of veneer tapes impregnated with thermoplastic material. The veneer tapes allow the fiber orientation in the wood to be used for load-oriented reinforcement. During layer-by-layer placement at a defined angle on a mold, like tape laying, the thin layers are specifically heated with laser radiation and bonded under a predetermined pressure to form three-dimensionally shaped composite parts. By compressing the early wood tracheids while retaining the late wood tracheids, responsible for the mechanical properties, WPC have considerably higher mechanical properties than conventional wood-based materials and open completely new possibilities for use and recycling. In the research project, a design methodology is being developed in parallel to the basic investigations of the manufacturing process, which describes the WPC as a “composite in a composite”: The load-aligned and highly compressed veneer strips as a composite of elongated plant cells (tracheids) are embedded in a plastic matrix. A numerical model based on a homogenization method is developed to calculate the temperature- and moisture-dependent mechanical properties of the individual cell wall layers of the tracheids. The results are then used to simulate the multi-layer laminate structure of the cell wall. The temperature- and moisture-dependent deformation behavior of the tracheids under pressure both radially and tangentially to the longitudinal direction is modeled using the finite element method and used to estimate optimal process parameters for the additive manufacturing of WPC molded parts. The load paths prevailing in the WPC molded part are determined by simulation, clustered and used to determine the load-appropriate orientation of the veneer strips. This is followed by a simulation of placement and compaction in the additive manufacturing process. The results are compared with the results of the experimental investigations and used for optimization.

• DFG Programme: Research Grants