The need for renewable bio-based materials that could replace well-established synthetic composite materials is rapidly growing. For example, bio-based materials are increasingly used in applications where a lightweight design should be combined with sustainability and recyclability. However, it is often very challenging to directly transfer the excellent properties of biological materials to a product in a scalable and cost-efficient manner. In this study, we combined delignified wood layers (veneers) and a starch-based glue into bio-based high-performance composites. First, we investigated the ideal amount of starch-based glue between the layers to prevent delamination in the final composite. Then, we produced laminates in unidirectional, cross-ply, and quasi-isotropic configurations using wet processing. Laminates with tensile properties up to 40 GPa and 200 MPa in tensile stiffness and strength, respectively, were fabricated with a very high fiber volume content of up to 80%. The high fiber volume contents led to mechanical interlocks between neighboring fibers and made the need for an additional matrix unnecessary. The water-based laminate process is cost-efficient and scalable and additionally allows one to make full use of delignified wood’s formability by producing shaped parts for various applications.@en

The development of sustainable materials from renewable resources is one of the key challenges in today's materials science. Wood has great potential to play an important role in future materials advancement due to its excellent mechanical properties and high abundance. In this regard, two novel concepts for the development of high-performance wood-based materials in scalable top-down approaches are presented. Both concepts, Densified Cellulose Materials (DCMs) and Delignified Wood Reinforced Polymers (DWRPs), are based on delignification and densification of wood. Matrix free DCMs possess good tensile properties with a stiffness up to 40 GPa and strength up to 250 MPa. The high mechanical properties are obtained by a combination of high fibre volume content (FVC) of up to 80% and stress transfer throughout the cellulose scaffold enabled by mechanically interlocked fibre-fibre interfaces. Matrix infiltrated DWRPs reveal excellent tensile properties with elastic moduli of up to 70 GPa and 600 MPa strength. The epoxy matrix is vacuum infiltrated into the scaffold before densification and curing and provides an additional stiffening effect. The low intrinsic density of cellulose fibres results in attractive specific tensile properties, which are above previously reported values obtained for natural fibre composites such as flax or sisal. By scalable open-mold vacuum processing, DCMs with high tensile properties can be fabricated to partially replace less sustainable materials such as glass fibre reinforced composites in the future.@en