Preparation of robust and reprocessable wood powder/dynamic polyurethane composites with integral static-dynamic hybrid networks

Preparation of composites that can fully utilize each component's strengths is challenging, especially in the realm of the plant biomass/polymer composites. Here, wood powders with static microstructured and nanostructured networks were combined with a dynamic polyurethane containing dynamic networks to fabricate integral static-dynamic hybrid networks (SDNs) connected through covalent and noncovalent bonds. Hot press-induced wood powder orientation and compression in the SDNs increase the contact area between the wood powder particles and the frictional force between the microfibrils of the wood powder cell walls. These chemical and physical interactions contribute to the high interfacial adhesion in the SDNs, enabling the wood powders and the dynamic polyurethane to achieve their full performance. Thus, the SDNs exhibit high mechanical properties and good thermostability, with tensile strength and flexural strength of 55.37 ± 4.49 MPa and 88.22 ± 3.67 MPa for the SDNs with a wood powder content of 70 wt%. The SDNs (with wood powder contents of 50, 60, and 80 wt%) failed to fully utilize the strength of both the dynamic polyurethane and the wood powder, resulting in lower tensile strengths. Additionally, benefiting from the reversible networks of dynamic polyurethane, the SDNs demonstrate satisfactory reprocessability, with a mechanical properties recovery ratio higher than 70 % even after being reprocessed three times, and they have the potential to be used as a carbon storage reservoir when made into products. Furthermore, the simple preparation process of SDNs is scalable and can be adopted to other waste plant biomass. • Composites with integral static-dynamic hybrid networks (SDNs) were fabricated. • The strengths of each component in the SDNs are fully utilized. • The SDNs exhibit high mechanical properties and good thermostability. • The SDNs demonstrate reprocessability and can be used as a carbon storage reservoir.